ALBERT

Description: Selection of tool geometry is an important aspect for an efficient friction stir welding (FSW), as it influences material flow, forces, and other output responses. In the present paper, a three-dimensional coupled thermo-mechanical model is proposed based on Lagrangian method to evaluate the performance of two different pin shapes, i.e., smooth conical and threaded conical. Experimentally obtained axial force and spindle torque are used to validate the model. Particle tracking method is used to visualize the material flow on advancing side, retreating side, and centerline of the weld. Results reveal that material flow is non-symmetric and unstirred region is lower for the threaded pin as compared to the smooth. Higher slip rate is predicted for threaded pin as compared to the smooth pin. Vertical flow is observed for the threaded pin and is almost negligible for smooth pin. Overview of current research

Description: We suggest a novel experimental technique to fabricate microscale metallic wrinkles on a curved surface to clear duplication of form using a contact and electro-replication process. As the first step, in order to fabricate polymeric master wrinkle patterns, a UV-curable adhesive was deposited on a substrate with 180 μm in thickness, and then it was weakly polymerized by short UV exposure of 5 s for generating the gradient of material properties along the direction of layer thickness. Then, wrinkles were generated on a skin of the weakly polymerized layer by compressive forces that occurred during a thermal post-processing. After that, the master was replicated using a PDMS mold. The metallic wrinkles were reproduced on a curved metallic surface using the replicated mold in a nickel-based electroforming system. For understanding the major process parameters of electro-replication, a Taguchi method was utilized. Through this work, the metallic wrinkles were well reproduced and we believe that the proposed method is a promising technology to fabricate metallic wrinkles that have rich potential applications such as heat transfer enhancement and surface modification of metallic structures.

Description: For carbon fiber-reinforced plastic (CFRP) composite components, especially advanced CFRP components with complex three-dimensional features, surface grinding is often needed to generate final dimensions and functional surfaces. Surface damages are frequently induced during surface grinding, reducing the load-bearing capability and service life of the components. Therefore, it is desirable to perform surface grinding of CFRP in a high-quality and high-efficiency way. Rotary ultrasonic machining (RUM) surface grinding has been investigated to machine CFRP for improved surface quality. Cutting force is one of the most important output variables for evaluating RUM surface grinding. The modeling of cutting force is essential to effectively control the occurrence of surface damages during RUM surface grinding of CFRP. In the RUM surface grinding process, the workpiece material is primarily removed by abrasives on the tool peripheral surface, thus it is essential to investigate the feed-direction cutting force model. However, such models are not available in the literature. In this study, for the first time, a mechanistic feed-direction cutting force model in RUM surface grinding of CFRP is established based on the assumption that the material is removed by brittle fracture. The mechanistic model has one parameter, fracture volume factor of the workpiece material, which needs to be determined by an experiment. There is a good consistency between theoretically predicted trends and experimentally observed results on the relationships between feed-direction cutting force and input variables.

Description: Open-architecture products (OAPs) meet users’ personalized requirements using functional modules and adaptable interfaces in the products. Although different methods have been proposed for product assembly planning, there is a lack of methods for OAPs considering both levels of assembly operations for product modules and components in products. This paper proposes a product structure graph and an assembly constraint matrix to represent constraints of product modules and components in OAPs for assembly sequence planning. Modules in OAPs are first examined for their feasibility to be assembled independently in an operation. If a module cannot be assembled as a sub-assembly, it will be divided into several sub-assembles or components with a revised product hierarchical structure graph. Assembly sequences of components in the module are planned based on the assembly constraint matrix of the components. The feasible assembly sequences of modules and components can then be formed. The proposed methods are verified in the application of an industrial product.

Description: This study aimed to present a novel method in the forward extrusion. In this study, the cross section of die aperture is engineered to smoothly change during the process, from a triangle shape to square shape. This novel method has been experimentally tested, and the feasibility of the process has been demonstrated. The process is numerically studied by finite element method, and the results correspond to the experimental ones. The possibility of producing products with complex variable cross section along the length has been proved by experimental results. The results showed that more homogeneous distribution of the effective strain is achieved while the extrusion speed is increased during the process.

Description: Chatter is a kind of self-excited unstable vibration during machining process, which always leads to multiple negative effects such as poor surface quality, dimension accuracy error, excessive noise, and tool wear. For purposes of monitoring the processing state of milling process and detecting chatter timely, a novel online chatter detection method was proposed. In the proposed method, the acceleration signals acquired by sensor were decomposed into a series of intrinsic mode functions (IMFs) by the adaptive analysis method named ensemble empirical mode decomposition (EEMD), and the IMFs which contain the feature information of milling process were selected as the analyzed signals. The two indicators power spectral entropy and fractal dimension which is obtained by morphological covering method are introduced to detect the chatter features. Then, both the frequency characteristic and morphological feature of the extracted signals can be reflected by the two indicators. To verify the approach, milling experiments were performed; the experiment results show that the proposed method can detect chatter timely and effectively, which is important in the aspect of improving the milling quality. And finally, in order to detect milling chatter timely, an online milling chatter monitoring system was developed.

Description: The impellers of centrifugal pumps are highly susceptible to the latent damage of corrosion and cavitation after long periods of transporting chemical fluids. To enhance the structural integrity and effective lifespan of impellers, this study applied mold flow analysis to the design of gating systems for 17-4PH stainless steel enclosed impellers. Our objective was to eliminate shrinkage and porous defects common in investment casting. We adopted various bottom, side, and top pouring systems with different pouring parameters to examine the behavior of the molten metal flow and solidification in the mold cavity. We designed a pressurized gating system with specific gating ratio to achieve a stable flow velocity at in-gates. Physical sensors preset in the interior of the cavity were also used to detect thermodynamic behavior and analyze phase changes during casting simulations. The probability of shrinkage defect formation was assessed using the retained melt modulus (RMM) and the Niyama criterion. Experiments and nondestructive inspections show that optimizing the design of the gating system prevented surface shrinkage and interior defects. The improvements also reduced post-processing time and costs, increased yields, and enhanced casting quality.

Description: Machine tool dynamic characteristics are seriously affected by the changes of the machining poses and the spindle bearing joints dynamic properties. As these changes contribute much more complexity and uncertainty for predicting the machine tool dynamic characteristics accurately, a new method is developed to research the changing regularity of the whole machine tool dynamic characteristics in generalized manufacturing space. In this method, the dynamic flexibilities at the spindle nose of x , y, and z directions in the focused frequency range are taken to represent the whole machine tool dynamic characteristics. The response surface method (RSM) and the orthogonal experiment design method are combined to establish the generalized dynamic response model, which contains the information of the spatial poses and the spindle bearing dynamic parameters. To establish this model, the simulations arranged by the orthogonal design are conducted by utilizing the dynamic model modified approach based on the validated finite element model (FEM) of the whole machine tool. With evaluating the fitting degree of this generalized dynamic response model, it can be used to predict the dynamic characteristics in the manufacturing space. Furthermore, an algorithm based on the established model is proposed to calculate the effect factors acting on the whole machine tool dynamic characteristics, which are caused by the changes of the spindle bearing dynamic parameters. The proposed analytical method has been applied in a three-axis vertical machining center to establish its generalized dynamic response model. The dynamic flexibilities at the spindle nose in the generalized manufacturing space are predicted, and they are validated by the dynamic experiments. With the calibrated model, effect factors of the spindle bearing joints are also obtained. All the predicted results support a theoretical basis on the optimal process routes planning, and the proposed analytical method can lay a foundation for further study on the dynamic information of the tool point.

Description: Accuracy detection for five-axis numerical control (NC) machine tools that can truly reflect their practical machining precision is of crucial importance. Standard test pieces are commonly employed for this purpose. However, poor accuracy detection performance is obtained when the test pieces used here are applied to five-axis NC machine tools. This paper introduces a new S-shaped test piece that is exclusively designed for the precision detection of five-axis NC machine tools. The S-shaped test piece integrates numerous characteristics associated with aviation parts and has been widely adopted by machine tool makers. This article presents a numerical model of the latest S-shaped test piece and shows that its side surfaces represent typical undevelopable ruled surfaces. The curvature changes along the ruled lines inevitably produce a theoretical error. Thus, machining methods seek to reduce the theoretical error as much as possible. Based on basic summaries of five existing positioning algorithms, a novel algorithm is proposed to position the tool head using three points, wherein two are tangential to the top and bottom boundary curves, respectively, and the third is tangential to the midpoint of the ruled line. The proposed positioning algorithm together with five existing positioning algorithms is applied to the S-shaped test piece, and a numerical error performance analysis is conducted. The results indicate that the machined surface reduces the theoretical error by at least 96% compared to all the existing numerical positioning algorithms except for Redonnet’s algorithm. Compared with Redonnet’s algorithm, the accuracy of the proposed algorithm is equivalent, although the proposed algorithm reduces the calculation time by 62.7%, and is not sensitive to the initial values. Hence, the computational process demonstrates that the proposed method is efficient, robust, and universal. Finally, simulation results were confirmed through an actual machining experiment.

Description: With this research, an implementation of an overlay and abstracting RESTful API (application programming interface) for 3D printers is proposed to expose these resources to the Internet for utilization within and for cloud services. This is to abstract the underlying communication structure and means for accessing and controlling a 3D printer resource in one of three ways. The first way is a proprietary protocol or a 3D printer driver in Microsoft Windows. The second way is the control via a USB-serial connection between a controlling computer and the printer resource. This protocol can either be in a proprietary format or based on open standards like G-Code (ISO 6983-1:2009). The third way of control is based on physical storage devices attached to the printer with machining instructions stored on them. This research excludes the communication and control means involving proprietary protocols or drivers due complexity restrictions within the implementation. The approach is designed with extensibility in mind so that future access to proprietary protocols can be added to the control API. 3D printer resources with only the third control method available are also excluded from this research due to their lack of remote controllability. This work describes the design and implementation of an abstraction API layer between varying software and hardware components with an extensible architecture for future hardware and software components for within the domain of additive manufacturing (AM). With this research, the connection to further cloud services as 3D printing resources as well as a cloud printing service for usage and control of this API is demonstrated. This enables the use of AM machinery within cloud or business process-oriented architectures as the AM machinery and the associated software are exposed in an abstract and unified way and usable as services.

Description: Hilbert–Huang transform (HHT) and time–frequency entropy were used to estimate the stability of short-circuiting gas metal arc welding (GMAW). First, the current signals were divided by empirical mode decomposition (EMD) into several intrinsic mode functions (IMFs). Then the IMFs were converted by Hilbert transform to Hilbert–Huang spectrum which describes the instantaneous time–frequency distribution of welding current signals. Since the uniformity of energy amplitude distribution with time–frequency reflects the stability, we introduced time–frequency entropy to quantify the energy distribution with time–frequency range in the HHT spectrum. We found HHT can effectively depict the amplitude with time and frequency distribution of welding current signals, and the welding was more stable when the time–frequency entropy was larger. Thus, this is a new way to assess and quantify the stability of short-circuiting GMAW.

Description: The presented work here is devoted to the definition of innovative methodologies to speed up the programming time of a robotized deburring task. The proposed solutions are defined in a standard cast iron foundry scenario, where the deburring workstations are equipped with flexible but inaccurate fixturing system, the working environment is dirty, and the production is characterized by small batches. The developed system exploits a 3D vision sensor, namely a single-point laser displacement sensor (SP-LS), in combination to a handshaking communication process for the robot-sensor information synchronization. Such approach enables the robot to be used as a measuring instrument allowing a fast reconstruction of 3D images extremely robust in hard working conditions. Adopting a two-stage methodology, the comparison of the reconstructed 3D point cloud with the nominal 3D point cloud allows the automatic adjustment of the robot deburring trajectories. An experimental campaign demonstrates the feasibility and the effectiveness of the proposed solutions.

Description: High accuracy manufacturing requires the utilisation of advanced signal processing and analytics to monitor, manage, and control production processes. These systems vary in size, scope, and complexity and have traditionally required the skill of multi-disciplinary individuals, for end-to-end application. Current research trends in digital manufacturing aim to remove this complexity through interoperability solutions encapsulated in cyber physical systems. These systems provide a platform for real-time heterogeneous data acquisition, analysis, and distribution. The focus of this research is to demonstrate the application of a cyber physical process monitoring system within an industrial case study. Specifically, a multi-scalable signal processing and analytic system is developed, for both user-driven and semi-autonomous production decision support in CNC turning machining.

Description: In order to increase cutting width, decrease tool path length, and improve machining efficiency, the spiral enter assistant line (SEAL) is embedded into a convex pocket to plan a spiral tool path. First, the inner offset curve of the pocket boundary undergoes equidistant division to acquire the external equidistant points. Subsequently, principal component analysis (PCA) and length factors optimization are employed to obtain SEAL. Next, vector operation is performed on the external equidistant points and SEAL to calculate the corresponding internal points. After connecting the external equidistant points and the corresponding internal points, a B-spline spiral tool path is planned based on linear interpolation and B-spline curve fitting. In addition, the length factors can be adjusted to modify the distribution and length of the tool path. Theoretical analysis and machining experiments demonstrate that compared to other conventional algorithms, the spiral tool path presented in this study has obvious advantages on cutting width, tool path length, and machining efficiency. These advantages are especially pronounced when the major principal axis is much longer than the minor principal axis.

Description: Three different shielding gas nozzles were designed for the narrow-gap laser-MIG hybrid welding of thick-section steel. Different gas flow behaviors produced by the three nozzles exerted great effects on the welding characteristics. While using the straight-trapezium shielding gas nozzle, unstable droplet transfer behavior with spatters and welding current wave were observed due to the unstable and high velocity of shielding gas. The weld with a mass of pores in a honeycomb distribution at the surface was produced by using the straight-trapezium nozzle, since the aft part of the molten pool could not be protected effectively during the welding process. Stable droplet transfer behavior and current wave were realized; qualified welds almost with no pores at the surface were obtained by using the square-outlet nozzle with boss or circle-outlet nozzle with boss.

Description: The paper focuses on the chatter stability prediction for a flexible tool-workpiece system in a turning process. The dynamic model of the turning process presented here considers two end conditions of the flexible workpiece. Chatter-free (stable) cutting parameters are obtained analytically and stability lobe diagrams (SLDs) of a turning operation are constructed using simulations to distinguish stable and unstable regions. The SLDs are constructed for a variety of tool and workpiece parameters affecting the flexibility/compliance of the tool-workpiece system to investigate the effects of these parameters on the stability of the turning process. The proposed analytical model has been validated with the turning experimental results.

Description: Tool wear is a major challenge when drilling CFRP. Cutting edge rounding quantifies the blunting of the cutting edge by considering the events happening in the flank–cutting edge–rake zone together by fitting a circle to this zone. The two interface zones, however, undergo wear in different ways. While the flank–cutting edge interface becomes rounded, the rake–cutting edge interface flattens out with drilling. Two new parameters, flank rounding (FR) and cutting edge flatting (CEF), are introduced to measure the damage to the flank and cutting edge, respectively. The nature of CEF and FR variation along the cutting edge shows that both are related. The chipping of the cutting edges is studied using a parameter called cutting edge roughness by monitoring the cutting edge topography. The progression of FR and cutting edge roughness along the length of the cutting edge shows that chipping may be related to the nature of FR progression. CEF could be easily measured using a simple measuring microscope and can be used to monitor drill wear.

Description: This paper aimed to restrain the processing defects of aluminum alloy honeycombs using in aerospace with low stiffness and thin-walled, such as burr and collapse edge. The honeycomb material was treated by new method named ice fixation, and a CNC milling machine was used for a series of cryogenic machining. The fixation strength was calculated and machining defect reasons were analyzed. The cryogenic milling mechanism with ice fixation was established at the same time. Results show that compared to the without ice or conventional fixation way, the honeycomb fixation force and strength are all greatly increasing and that can reach 287 N and 19.1 kPa, respectively. Meanwhile, the processing defects are effectively suppressed. Others the cutting depth has greater influence on surface quality, and it makes the milling force improved three times, while the improvement of fixation and milling force and the cryogenic processing are the main reasons of reducing defects. The ice fixation cryogenic processing provides a new and effective method for aluminum alloy honeycomb with low rigidity and thin-wall.

Description: Micro-injection molding (μIM) is considered to be an important method for fabricating micro-needle array which is widely researched in recent years, and mold temperature is one of the important factors that affect the mold filling quality of the polymer melt during the micro-injection molding. In this paper, an infrared heating method is adopted to raise the mold temperature rapidly for improving molding quality of micro-needle array. According to the simulation of the reflector type, which has an important effect on the efficiency of infrared heating system, an infrared heating system with high efficiency is developed and used in the developed infrared-heating-assisted μIM system. A series of verification experiments are carried out to verify the feasibility and the heating effect of the developed system. The experimental results show that the developed infrared heating system can achieve high efficiency and uniform heating of mold surface and the infrared-heating-assisted μIM process for fabricating micro-needle array can improve mold filling capability of the polymer melt and optimize the replication quality (filling height, uniformity, and shrinkage) of parts.

Description: Warehouse building design tackles the industrial issue of best studying the overall configuration and dimensions of the storage systems reaching one or more predefined target of performance. This paper proposes a multi-objective model for the warehouse building design to minimize the cycle time, the total cost, and the carbon footprint of the storage system over its lifetime. The goal is to define the overall building dimensions, addressing the target storage capacity and the handling performances, balancing the aforementioned three objective functions. The cycle time computes the average duration of the pickup and drop-off activities, while the system total cost and carbon footprint rise over the entire warehouse lifetime, including the installation and operating phases. The developed model is applied to design the warehouse for an Italian food and beverage company. Results highlight that the total cost and the carbon footprint functions lead to similar warehouse configurations distinguished by a compact vertical structure. On the contrary, the cycle time function takes advantage of a flatter and wider building even if a dramatic increase of the environmental (+40%) and cost (+10%) objective functions occurs. The proposed best balance solution limits the total cost and carbon footprint increment below 1% compared to their single-objective optima, while the cycle time worsening is limited to 4% compared to the optimal cycle time solution.

Description: Over the last decade, Product-Service System (PSS) has been established as a prominent business model which promises sustainability. A great amount of literature work has been devoted to PSS issues, but there is fairly limited published work on integrated and easily applicable evaluation methodologies for PSS design, as well as a lack of Lean PSS approaches. Contributing to these directions, the present work introduces a framework for the evaluation and improvement of the Lean PSS design using key performance indicators (KPIs), Lean rules, and sentiment analysis, aiming to feed all the stages of PSS design lifecycle. According to the evaluation phase, a certain appropriate set of KPIs is selected and suggested to the PSS designer via a context-sensitivity analysis (CSA) tool through a pool, which have been identified after intensive literature survey, and systematically classified into five main categories: design, manufacturing, customer, environment, and sustainability. According to the same phase, sentiment analysis has been used to identify the polarity of the customer opinions regarding the PSS offerings. During the phase of Lean design assistance, Lean rules are selected using CSA and are suggested to the designer to ensure the minimization of wasteful activities. Enabler for the context awareness is the availability of feedback gathered from the manufacturing, shop-floor experts, and the different types of customers (business or final-product consumers), as well as the PSS lifecycle which the designer treats. The proposed framework is implemented in a software prototype and is applied in a mold-making industrial case study.

Description: In the paper, a fault diagnosis of the induction motor (IM) at closed loop is presented, and the fault considered in the machine is the adjacent broken rotor bars. The technique of control uses is the vector control in order to preserve the speed regulation and compensate the fault effect and to ensure the service continuity of the machine. Several electrical and mechanical quantities (i.e., rotor speed, quadratic current components, and stator phase current) are analyzed using the fast Fourier transforms (FFT) for the detection of the rotor bars’ fault. The control strategies have been employed in Matlab/Simulink linked to real-time interface (RTI) via dSpace 1104. The simulation and experimental results show the effectiveness of machine control under rotor failure. Moreover, the FFT technique analysis on the closed-loop control signals give clear information about the presence of fault, where the quadratic component I qs offers an advantage and becomes an appropriate characteristic for the fault detection.

Description: The complex cutting edges of the drill bit and different machinability properties of novel hybrid fibre-reinforced polymer (FRP) composites make it challenging and difficult to obtain consistent and damage-free holes. While the findings presented in previous literatures have shown that the desired drilling parameters are feasible for minimization of delamination damage, the changing in the thrust force is known to play a critical role in influencing the size of the delamination zone. In order to elucidate the mechanism of drilling-induced delamination for hybrid FRP composites, an analytical study of drilling characteristics for this novel material has been attempted. This analytical model was established based on the principle of virtual work (energy balance equation), linear elastic fracture mechanics, classical plate bending theory, and the principle of rule of mixture. Results of this analytical study indicate that the delamination damage can be alleviated if the applied thrust force is lower than the critical thrust force value. The applied thrust force and delamination damage from experimental results were used to validate the proposed model. A good agreement between the estimated critical thrust force and the measured thrust force was evident in this particular study.

Description: The new flexible-bending technique is used in three-dimension (3D) bending of profile and tube cross-sections. The bending radius of the forming part of profile or tube is adjusted by numerical control. The flexible-bending has some advantages, such as free definable bending geometry, and avoidance of re-clamping. The rapid development of Chinese aerospace industry has raised the demand for 3D bending profile. However, traditional bending methods of profile fail to meet the requirements of high applicability, and personalized small batch production. In this article, we studied the flexible-bending formability of asymmetric cross-section L-shaped thin-wall aluminum. The simulating calculation was carried out on finite element simulation software. Comparisons between simulation and experiment show that error analysis is needed. After the investigation of forming springback, side bending and twisting, we conclude that the springback amount changes to some extent following the increase of uplift amount H of bending die in the Y -direction. The springback can be optimized according to the variation trend. The side bending is eliminated by increasing the reverse displacement of the side bending trend. The twisting defect is relieved by intensifying the reverse displacement along the X -axis and altering degree-of-freedom UR3 along the Z -axis.

Description: The purpose of the research conducted is to describe the consequences of variation in the welding industry and the effect it has on manufacturing productivity. The potential has shown to be hidden in unnecessarily stringent requirements and over-processing. This has been studied in steps: customer requirements, design and analysis, preparation, welding, and assessment. The effect of variation in each step has been analyzed including estimations of its productivity improvement potential. Theoretically, in a perfect situation, with customized requirements and eliminated variation, more than half of all welding could be removed. Such a reduction is certainly neither practical nor possible. However, a sensible, controlled reduction could still have a very high impact. The financial implications are therefore substantial. The improved productivity of the manufacturing resources could be used for business development and increased production. To be able to realize the potential, interdisciplinary efforts are necessary. Management across different functions need to agree on the intended product life and make decisions thereafter.

Description: This paper aims to investigate the influence of defect morphology, defect size, and SDAS on the fatigue behavior of A356-T6 aluminum alloy. A 3D finite element analysis for specimens containing different pore morphologies—(i) spherical pore, (ii) elliptical pore, and (iii) complex pore—was implemented. The Chaboche kinematic hardening model embedded in Abaqus is used to characterize the material response during cyclic loading. Kitagawa diagrams for defective A356-T6 are simulated using the defect stress gradient (DSG) approach. A good agreement is found between experimental and numerical results for predicting fatigue limit in the case of spherical defects. The impact of defect morphology on the fatigue resistance is clearly demonstrated. This paper shows that aluminum fatigue resistance is strongly dependent on the defect size, SDAS, and the defect morphology. Therefore, a mathematical model that takes into account the impact of these three parameters is developed using response surface (RS) approach to predict fatigue limit of porous aluminum alloy. Moreover, the effects of defect morphology, defect size, and SDAS on fatigue response and their interactions under fully reserved tensile loading are investigated.

Description: Selective laser melting (SLM) as a part of 3D printing technology has been a novel industrial manufacturing process nowadays. However, the collection of metal powders emitted from the working plane is significant for the SLM process. The uniformity of the flow passing through the SLM working chamber, which helps collect emitted powders, has been considered as a key solution. In this study, for the purpose of improving the flow uniformity, a blow-to-suction device composed of a trapezoid push nozzle, a working chamber, and a suction tunnel was applied. Various parameters, such as the width of trapezoid push nozzle, the width of suction tunnel, and the nozzle-to-plane distances, were examined experimentally and computationally. Hot-wire velocity measurement and smoke flow visualization were used to verify the reliability of the simulation. Through the results of degree of uniformity (DOU), the momentum exchange between the suction and blow sides plays an important role for producing a uniform flow through the working chamber. In addition, higher suction velocity as well as larger nozzle-to-plane distance result in relatively better uniformity of the flow.

Description: Companies devoted to manufacture operations of small sets for the automotive industry need to follow the usual quality standards, accomplishing with the delivery times. Commonly, these operations are performed with automatic or semi-automatic equipment in order to increase their competitiveness. Some partially automated systems allow complex manufacturing operations but cannot always ensure the required level of quality. This work was developed in order to solve quality problems reported on the transmission system of automotive windshield wipers, where a brass’s tube is inserted and partially deformed at one of the tips. However, tubes’ suppliers cannot ensure the dimensional accuracy needed by the semi-automatic system, and the manufacturing equipment is not able to detect and reject these components before the assembling process, resulting in the production of defective sets. In order to overcome this problem, impossible to solve using the current semi-automatic equipment, a new solution was developed through a fully automated system under controlled costs, enabling the set manufacturing operation in a competitive way.

Description: As the basis for a flatness control system, flatness actuator efficiency describes an actuator’s control ability, but it is difficult to obtain an actuator efficiency factor accurately through rolling tests because of the complicated subsidiary facilities of the mill. This paper proposes a novel simulation approach that is applied to obtain the actuator efficiency factors in terms of work roll bending, intermediate roll bending, and intermediate roll shifting for a six-high Universal Crown Control mill (UCM mill). A three-dimensional (3D) finite element model of the mill was developed to simulate the dynamic strip rolling process. The validation of rolling experiments shows that this model has enough precision, where the relative error of strip thickness between simulated values and actual values is less than 1.0%. The effects of the actuators on strip thickness profile, crown, edge drop, and elongation difference of longitudinal fibers were investigated. In the case of different actuator parameters, the curves of actuator efficiency factors were obtained and quantitatively descripted by truncated Legendre orthogonal polynomials. The mechanism of flatness control was studied based on an analysis of the actuator’s influence rule on the elastic deflection of rolls and 3D distribution of rolling pressure. The results indicate that the curves of actuator efficiency factors have a symmetrical upside-down v-shaped distribution and contain the quadratic and quartic flatness components. The actuator efficiency factors of intermediate roll shifting have a nonignorable variation with the change of actuator parameters. This study is the first attempt to obtain actuator efficiency factors for UCM mill using an elastic–plastic finite element method.

Description: Sustainability is a growing interest for industry to integrating and assessing social, environmental, and economic objectives. Involute gear and single-pump feed technology are difficult to satisfy the requirements of sustainability for high-homogeneous medium and low-loss situations. To improve the relative displacement and reduce the volume of the pump, an innovative three-gear micropump was designed. The gears were patterned with Logix tooth profiles which have lower undercutting tendency and are easy to design with a reduced number of teeth. The double-pump confluence technology was used to reduce the flow pulsation based on phase compensation. In this paper, the structural parameters of Logix gear were first calculated through mathematical analysis. Then, a micropump composed of three Logix gears was designed based on the selected parameters and double-pump confluence technology. The Logix gear was manufactured by micromilling experiments, and the three-gear pump was assembled. At last, a pressure fluctuation test platform was implemented to investigate the fluctuation of the three-gear pump and the transmission noise. Results showed that the displacement of the three-gear micropump was doubled compared with the conventional involute gear pump, with 50% flow pulsation reduction. The transmission noise of the Logix gear pump was also reduced. The outcome of this research will contribute to the development of simplified, safer and anti-fuel-burning gear pump systems, and environment-friendly and sustainable manufacturing of such systems.

Description: Electrochemical discharge machining (ECDM) is a cost-effective machining process used to shape non-conductive materials such as glass and ceramics. The process can overcome poor machinability of hard and brittle materials. Different types of physical phenomena can be added to the ECDM components to improve the machining efficiency. As the main target of this paper, ultrasonic vibration was integrated to the cathode of the ECDM process (UAECDM), which resulted in vibration concentration only to the machining zone. In order to design the experimental configuration, modal analysis was used. Machining speed was the main output of this investigation. Gas film and electric discharge were two main physical phenomena during ECDM. The thickness of gas film, location, and pattern of discharges were determined, experimentally. Also, current signal was a useful tool that could record significant details of involved mechanisms and phenomena during machining. Images of gas film showed that the application of ultrasonic vibration decreased the thickness of gas film by 65%. In addition, the vibration amplitude of 10 μm created the most uniform current signal, which had a considerable effect on the material removal rate (MRR). Results showed that all levels of vibration amplitude increased the machining speed during discharge and hydrodynamic regimes of the machining process.

Description: Modern manufacturing systems are expected to be flexible and efficient in order to cope with challenging market demands. Thus, they must be flexible enough as to meet changing requirements such as changes in production, energy efficiency, performance optimization, fault tolerance to process or controller faults, among others. Demanding requirements can be defined as a set of quality of service (QoS) requirements to be met. This paper proposes a generic and customizable multi-agent architecture that, making use of distributed agents, monitors QoS, triggering, if needed, a reconfiguration of the control system to recover QoS. As a proof of concept, the architecture has been implemented to provide availability of the control system understood as service continuity. The prototype has been tested in a case study consisting of an assembly cell where assessment of the approach has been conducted.

Description: The grinding process is still an important manufacturing process for the machining of automotive components. For power train components, ultra-high carbon steel (UHC-steel) is a promising new innovative alloy because of its low specific density. Results from turning of UHC-steel showed that the texture of UHC-steel significantly differs from conventional steels. Furthermore, extremely hard carbides, which are embedded into a soft ferrite matrix, result in a UHC-steel specific machining behavior and a high tool wear rate. Therefore, UHC-steel is marked as a difficult-to-cut material. So far, there are no research results available for the grinding of UHC-steel. Therefore, fundamental investigations were conducted in order to analyze the material removal and chip formation mechanisms. Scratching tests with a geometrically defined cubic boron nitride cutting edge showed ductile material removal mechanisms for a single grain chip thickness variation from h cu  = 1.5 up to 14 μm. Analysis of the contact zone by means of an innovative quick stop device confirms these results.

Description: Nowadays, along with the application of new-generation information technologies in industry and manufacturing, the big data-driven manufacturing era is coming. However, although various big data in the entire product lifecycle, including product design, manufacturing, and service, can be obtained, it can be found that the current research on product lifecycle data mainly focuses on physical products rather than virtual models. Besides, due to the lack of convergence between product physical and virtual space, the data in product lifecycle is isolated, fragmented, and stagnant, which is useless for manufacturing enterprises. These problems lead to low level of efficiency, intelligence, sustainability in product design, manufacturing, and service phases. However, physical product data, virtual product data, and connected data that tie physical and virtual product are needed to support product design, manufacturing, and service. Therefore, how to generate and use converged cyber-physical data to better serve product lifecycle, so as to drive product design, manufacturing, and service to be more efficient, smart, and sustainable, is emphasized and investigated based on our previous study on big data in product lifecycle management. In this paper, a new method for product design, manufacturing, and service driven by digital twin is proposed. The detailed application methods and frameworks of digital twin-driven product design, manufacturing, and service are investigated. Furthermore, three cases are given to illustrate the future applications of digital twin in the three phases of a product respectively.

Description: The magnetic support technology has been widely recognized to be an ideal way of improving the welding quality. In current work, the 7-mm 5A06 Al plates are laser welded with an external static magnetic field aligned vertically to the welding direction. The bead formation, grain configuration, alloying element distribution, and weld hardness are experimentally analyzed to reveal the magnetically dominated flow behavior within the weld pool. The results indicate that, under the function of the magnetostatic field, the continuity and stability of the aluminum welds are improved and the weld width especially on the bead surface diminishes obviously with increasing magnetic flux density from 0 to ~238 mT. The evolutions on weld profile are caused by the induced electromagnetic suppression on the molten convection, especially the Marangoni. The grain enlargement, remarkable grain-boundary segregation, and chemical heterogeneity are found in the seams with magnetic field applied since the blocked melt flow restrains the thermal transfer and decreases the nucleation rate and supercooling degree. The weld hardness achieves lower in fusion zone but higher in HAZ compared with the control case, which is consistent with the microstructure characteristics.

Description: The purpose of the research is to study the form grinding processes and properties of self-developed, new micro-crystal corundum grinding wheels. Aiming at this, this study conducted experimental research and theoretical analysis to form grinding 20CrMnTi steel tooth surfaces by using micro-crystal grinding wheels. The theoretical models and formulae for grinding forces of the form grinding of involute gears were constructed which were able to demonstrate actual experimental situations and show a better theoretical basis and applicability. This research also deduced the relationships between the grinding parameters and the roughness of tooth surfaces, grinding temperature, and grind-hardening burns, which provided constraints for optimally selecting grinding parameters in subsequent work. Furthermore, this study also established the relationship between the tangential grinding forces and the grinding temperature and grind-hardening burns, offering an important reference for the prediction of grinding temperature and avoiding tooth burning through on-line detection of the tangential grinding forces. In addition, this study also described the relationships between the grinding forces and the temperature and roughness of the tooth surfaces with grinding speed, and the radial feed and axial feed rates.

Description: The explicit temperature function of dual laser welding was presented, and the effect of welding pass distance and heat source distance on the thermal history was analyzed. There was excellent correlation between analytically solved and finite element method (FEM)-predicted dual laser welding temperature field. The analytical temperature function is applied to study the static recrystallization kinetics upon dual laser welding of nanobainite steel. By calculation, the optimal welding process parameters can be obtained when the static recrystallization fraction takes the maximum value. The corresponding temperature is above the martensite transus temperature and is appropriate to produce sufficient plastic strain in the austenite grains.

Description: In this study, a three-dimensional model was developed to investigate the temperature fields during a double-sided laser welding process of T-joints, and the correlations between the thermal characteristics and the mechanical properties were researched in details. To verify the modelling results, welding experiments were conducted with two different welding parameters and the geometrical dimensions of the weld pool were measured. It was found that there was a good agreement between the calculated and the measured results. The calculated results showed that the temperature profile was bilateral symmetry along the stringer centre, and the temperature gradient became greater as running far from the stringer centre, especially on the skin side. All of the tensile specimens were fractured along the fusion line on the skin panels for the head and the hoop tensile tests. The loss of the alloying elements near the fusion line on the skin side resulted in the lowest micro-hardness value appeared here, and made it to be the weakest region of the welded T-joints. The calculated thermal cycles indicated that the materials closest to the fusion line on the skin side had been staying at higher temperature for a longer time, and which is the essential reason for the fracture behaviour, micro-hardness distribution and alloying elements distribution of the double-sided laser welded T-joint.

Description: This study is made to investigate the effects of applying double-pass continuous wave laser polishing on the parameters of areal average surface roughness, two mechanical properties, and microstructure of SKD 61 tool steel. These parameters are partly compared to those in the single-pass specimens. The specimens before conducting double-pass laser polishing are prepared using the conditions of the specimen with the smallest surface roughness in the single-pass specimens, with the aim of examining the possibility of further reducing surface roughness. The smallest surface roughness value of the double-pass specimens has a value slightly larger than that of the single-pass specimens. An appropriate shallow melting for a substantial reduction in the grinding marks of the as-received specimen is used to prepare the single-pass and double-pass specimens with the smallest surface roughness. The surface roughness value is controlled by the contents and intensities of α-ferrite and γ-austenite in the sample, thus the composite grain size. In the single-pass specimens, the austenite lattices appear when the deposited energy is higher than the critical value, laying between 60.75 and 66.81 J/mm 2 . In the double-pass specimens, the austenite lattices disappear when deposited energy is higher than the critical value between 81.00 and 91.13 J/mm 2 . The growth of γ-austenite can increase the composite grain size. These two kinds of polishing show the same characteristic, which is that the growth of γ-austenite can increase the composite grain size. The intensity of the γ-austenite and the composite grain size are two of the governing factors with regard to the surface roughness of the specimen. Either a decrease in deposited energy in the double-pass specimens or an increase in deposited energy in the single-pass specimen is favorable for an increase in surface roughness in the non-zero intensity region of austenite.

Description: Inexpensive tool condition (TC) monitoring plays a significant role for less human duty machining process in large-scale manufactory. A time-sequential spindle current-based tool breakage diagnosis technique with least squares support vector machine (LS-SVM) classifier is investigated to provide an inexpensive on-line TC monitoring system for milling process. The recognition technique consists of a spindle motor current feedback sensor, a signal processor, and an intelligent classifier. The processor generates machining condition features with Sym6 wavelet transformation to decompose the feedback signals in time domains to generate sequence samples. The features involving both normal and broken tool conditions during machining are fed into the classifier to conduct kernel-based LS-SVM training. With the transformation and training, an object oriented representation function as the LS-SVM classifier is set up and then utilized to diagnose tool fractures in the real time under varying cutting conditions. Experiments were conducted on a milling platform with the built monitoring system consisting of a current acquisition system and its processing software. Experimental results show high accuracy rate and high calculation performance in on-line monitoring of cutting tool conditions for milling process.

Description: This approach regarding metal cutting in steel reveals the likely mechanisms behind a two-body abrasive wear. The theory is based on the assumption that ceramic hard inclusions in the secondary and tertiary cutting zones cannot to any significant extent be deformed plastically. The inclusions, in most cases roundish bullet-type particles, are forced to rotate or break due to the large shear stresses in the cutting zones. A bullet-type particle cannot efficiently cut or wear on the cutting tool rake and tool flank, but when the particle is torn apart, efficient sharp edges are created. Those edges are then, due to the elongation and contraction of the matrix material, pressed out towards the cutting tool, where they, while still rotating, cut until their cutting geometry become less favourable and at that point break into small fragments, which together with the matrix material are welded on the tool clearance and the tool rake faces. Those deposits with particle remnants and chips from the cutting tool contain 30–40% of ceramic material. The rest is matrix material from the workpiece. The understanding of this mechanism opens new ways to improve cutting materials, both coating and substrate, and the workpiece materials.

Description: Assembly sequence planning (ASP) plays an important role in intelligent manufacturing. As ASP is a non-deterministic polynomial (NP) hard problem, it is scarcely possible for a brute force approach to find out the optimal solution. Therefore, increasing meta-heuristic algorithms are introduced to solve the ASP problem. However, due to the discreteness and strong constraints of ASP problem, most meta-heuristics are unsuitable or inefficient to optimize it. Harmony search (HS) algorithm is one of the most suitable meta-heuristics for solving the problem. This paper proposes a dynamic parameter controlled harmony search (DPCHS) for solving ASP problems including a transformation of the assembly sequences by the largest position value (LPV) rule, initializing harmony memory with opposition-based learning (OBL) and designing dynamic parameters to control evolution. The key improvement to former work lies in the introduction of a dynamic pitch adjusting rate and bandwidth, which are adapting their value during the evolution. The performances of the DPCHS and the fixed harmony search algorithm are compared thoroughly in the case studies. Meantime, the efficiency of this algorithm in solving ASP problems is tested using two cases, and the results of other popular algorithms are compared. Furthermore, the DPCHS has been successfully applied to an industrial ASP problem.

Description: Large aperture optical components are widely used in deep space exploration and high-precision earth observation system. Ion beam figuring (IBF) is usually used as the last polishing process, and its polishing accuracy determines the optical primary mirror precision, so an IBF machine plays a very important role in the production process of large-size optics. In this paper, the state-of-the-art large-aperture IBF equipment is introduced firstly. Next, the structures, equipment parameters, and design considerations of our IBF equipment are presented. Motion accuracy and dynamic performance are the two prioritized design issues; all researches are carried out around these two issues. Then, the key design points and characteristic analyses of IBF machine are presented, including structure analysis and optimization of the vacuum chamber, the relationship analysis between the dynamic performance of the moving system and the polishing accuracy, and multi-objective optimization design and modal analysis of motion components. Finally, the dynamic characteristics and motion errors of the IBF machine are tested, and the test results show that the machine performance indexes meet the design requirements.

Description: To resolve the problems of uniformity and efficiency of soft abrasive flow (SAF) processing for complex titanium alloy surfaces, a gas compensation-based abrasive flow (GCAF) processing method is proposed. By the constrained modules, an enclosed flow passage covering the titanium alloy surface is built up, in which the gas phase is injected to enhance the turbulence intensity of abrasive flow. Taking the constrained flow passage as the objective, a three-phase fluid mechanic model for GCAF is set up based on the realizable k - ε model and the mixture model. The profiles of velocity and dynamical pressure of abrasive flow field in the constrained flow passage are obtained, and the turbulence variation regulars caused by gas compensation are revealed. Numerical results show that the proposed method can strengthen the turbulence intensity of abrasive and improve the distribution uniformity of dynamical pressure. A GCAF processing experimental platform is developed, and the experiments are performed. The results prove that the proposed method can obtain better processing efficiency and uniformity, the average surface roughness is less than Ra 0.3, and the surface topograph of micro-peak and micro-valley can reach less than 50 and 10 μm, respectively.

Description: A uniform design method was used to obtain the active flux formula for direct current electrode negative polarity activated tungsten inert gas (DCEN A-TIG) welding of 2219 aluminum alloy. According to the test results of the tensile strength of welded joint, a mathematical model was established to determine the best component of each component in the active agent and the correctness of the regression equation was verified. Compared with conventional TIG welding without active agent, DCEN A-TIG welding can effectively avoid the presentation of macroscopic and microscopic weld porosity, increasing penetration and strength of the welded joint. The three surfaces in the DCEN A-TIG weld zone presented different morphologies. The upper surface of the weld zone was composed of strong directional dendrites, whereas the cross section and longitudinal section of the weld zone were mainly composed of equiaxed dendrites. Cellular crystals were also observed on the bottom of the longitudinal section. The base metal of the joint was the hardest, and the hardness in the heat-affected zone was higher than that of the weld zone. The weakest area in the welded joint was near the fusion zone. Compared with conventional TIG welding, DCEN A-TIG welding can provide advantages.

Description: The cooling effect is better than conventional cooling channels because the conformal cooling channels have a uniform distance between the mold surfaces and the channels. In this study, a new method aiming to enhance cooling efficiency in the low-pressure wax injection molding process was proposed. It was found that a reduction in cooling time of about 81% can be obtained when a wax injection mold with conformal cooling channels is compared to that without cooling channels. In addition, a rapid tooling fabricated by this technology has some distinct advantages such as rapid tooling size, interior quality of conformal cooling channels, production costs, and post-processing operations compared to the selective laser sintering technology, selective laser melting technology, and diffusion bonding technology.

Description: The forming temperature of cross-wedge rolling (CWR) usually ranges from 950 to 1150 °C, but reducing the forming temperature has some advantages. This paper presents a comprehensive study of warm and hot cross-wedge rolling by using high-strength bolts as a case. Numerical simulation and experimental trials were conducted to make a detailed comparison of warm and hot cross-wedge rolling. Forming quality, microstructure, and mechanical properties of the rolled rods were investigated using scanning electron microscopy (SEM) and tensile testing. The results show that the rolling force and torque of warm cross-wedge rolling (WCWR) are more than three times greater than those of hot cross-wedge rolling (HCWR), and the workpiece rolled by WCWR shows more pit and stacking defects but fewer central cavities. The dispersing spheroidized cementite on ferrite matrix generated in WCWR results in decreased hardness and tensile strength of the rolled rods and a significant increase of elongation, which improves subsequent machinability.

Description: Research into the single grain cutting mechanism is important for understanding complex grinding mechanisms. Based on the characteristics of ultrasonic vibration, the motion equation of the grain is established, and the generated trajectory is theoretically analyzed. By adopting the method of combining high-speed grinding technology with ultrasonic vibration, abrasive wear forms of single cubic boron nitride (CBN) grains under common and ultrasonic conditions are studied. Further studies are conducted on the influence of the grain itself and the main grinding parameters on abrasive wear. Research shows that the main forms of abrasive wear during ultrasonic-assisted grinding are shearing wear and removing wear. However, common grinding leads to micro-crushing wear and a small amount of abrasion wear; the different forms of wear correspond to different grinding force signals. The greater the initial grain protrusion height, the greater is the abrasion of the protrusion; for the same grain protrusion height, the abrasive wear due to ultrasonic-assisted grinding is larger than that due to common grinding. As the grinding depth increases, the abrasive wear of both processing modes increases; however, in the case of ultrasonic machining, the abrasive wear increases slowly and is larger than that under common grinding. This study provides a certain decision basis for real-time monitoring of the ultrasonic-assisted high-speed grinding process. Additionally, it provides guidance and reference for the manufacture and selection of the grinding wheel and for the selection of reasonable processing parameters.

Description: Additive manufacturing technology (AMT) is a topic that is of considerable ongoing interest. The application of robots enhances the flexibility and intelligibility of the AMT. However, the traditional robot teaching programming method is tedious and complicated, which is one of the key challenges for developing a robot AMT technique. This paper proposes a new robot programming method based on the computer-aided design (CAD). Firstly, the geometry information of the CAD model is extracted in accordance to the stereo lithography (STL) data format. Secondly, the CAD topological structure is established based on the edge topological information. On the premise of guaranteeing the model precision, the CAD model error is analyzed. The particle swarm optimization (PSO) method is applied to raise the efficiency of the process.Finally, the robot path is automatically generated layer-by-layer from the CAD model and the proposed method is validated by an experiment of cladding a blade. The experiment result shows that the CAD-based automatic path generation and optimization for laser cladding robot is of higher efficiency and better accuracy than the ones with the robot teaching programming method.

Description: This paper presents an autonomous detection and identification of the weld seam path in different path shape. In seam path, detection and tracking approach are implemented in two stages: (1) pre-processing and (2) noise reduction. The edge remaining in the segment image was analyzed to remove those that not belong to seam. The piecework consists of straight line, zig-zag, and half-moon joints which are typical to welding applications. The seam path detects the position from start to end of the path by using two stages: (1) a new approach based on shape of weld seam path and (2) weld seam path representation. Finally, seam path can allocate the position of path from start, mid, auxiliary, and end points in x-y coordinated to instruct the welding robot to weld. The proposed system was analyzed in term of accuracy for position and distance error of the weld seam path between the proposed approach and a “ground truth” seam path shape lines. However, in vision system, it is a challenging especially in welding environments due to poor contract, reflection from metallic surface, shadow from parts, and imperfection on the workspace.

Description: Maintenance is carried out to prevent the occurrence of events that lead to malfunction and interruption of the production process or the operation of the concerned equipment. One of the main approaches in maintenance is to identify the risk of equipment failure mode. Whereas by reducing the high risk of failure mode the reliability and availability of equipment enhanced and the cost of shutdown reduced, identifying the risk of failure is important. In this paper, a fuzzy hybrid approach, including failure mode and effective analysis (FMEA), decision-making trial and evaluation laboratory technique (DEMATEL), and analytic network process (ANP), is presented to select an appropriate maintenance policy through identifying the risk of failures. The authors aim to develop a risk-based method for selecting a proper maintenance strategy to have available and reliable tamping equipment in railway of Iran. Because of considering the same weight of risk factors, failure occurrence, failure severity, and failure detection ability in FMEA, the traditional FMEA method cannot correctly predict the system’s behavior. So, in this paper, the risk factors as fuzzy variables are proposed and evaluated using fuzzy linguistic terms and fuzzy ratings. In a case study, the present approach is utilized for evaluation and determination of the risk of failure modes for a railway company. At first, fuzzy FMEA is used to identify the main risk and sub-risk of failure modes. Second, fuzzy DEMATEL method is used in order to put forward the interrelationship among the main risks which are determined through fuzzy FMEA. Then, the weights of the sub-risks are calculated by fuzzy ANP approach on the basis of cause–effect relationships that are exposed through DEMATEL method. Finally, the weights of sub-risks are determined by multiplying the weights which have been obtained from fuzzy FMEA to the weights of ANP supermatrix. The weights of sub-risks were determined on the basis of these examined dependencies, and these weights were used for a tamping machine to determine maintenance policy. Finally, some strategies and suggestions have been drawn concerning the needs to reduce the risks and improve the equipment’s availability.

Description: In the grinding process, to achieve improved tribological conditions between wheel-chip-workpiece interfaces and minimize the effects of thermal damages, such as loss of hardness and cracks for example, it is needed to minimize the high amount of heat generated by the process. In addition to the correct adjusting of the cutting parameters, it is also to select an efficient coolant delivery technique (that includes coolant concentration, coolant flow rate, and nozzle geometry) and properties of abrasive wheels for successful grinding. Therefore, seeking for cooling-lubrication techniques with improved coolant efficiency and that can preserve surface integrity of the workpiece, as well as that make rational use of cutting fluids, becomes indispensable. Into this context, this investigation aims to evaluate the performance of different coolant-lubrication conditions during the surface grinding of AISI 4340 steel with a vitrified bonded CBN superabrasive wheel under various cutting conditions. Three coolant delivery techniques (flooding, MQL, and optimized Webster system) were tested. The input cutting parameters was depth of cut values (20, 50, and 80 μm). Tangential component force, specific energy, surface roughness, microhardness and surface residual stress of the machined surfaces, as well as abrasive wheel wear and G ratio were monitored and used to assess the performance of the different coolant-lubrication under the conditions investigated. The results showed that, in general, the optimized technique outperformed other coolant techniques in all the parameters evaluated because of the better access of cutting jet to the grinding area, especially at more severe cutting conditions. MQL technique exhibited superior performance in terms of cutting force and specific energy, but it was in general responsible for generation of poorer finishing and the highest microhardness variation in regions closer to machined surfaces. With regard the residual stresses, they were predominantly compressive, irrespective of the depth of cut and cooling-lubrication technique employed. A slight variation of the residual stresses values with depth of cut after machining with the optimized and the MQL coolant technique, unlike the pattern observed after machining with the conventional coolant delivery technique. Finally, no significant thermal damages or cracks were observed on the machined surfaces after machining under all the cutting conditions.

Description: Application of vegetable-based nanolubricants in machining operations has been promoted due to the environmental concerns and higher demand for better quality of machined parts. In this study, lubrication properties of copper oxide nanofluids in surface grinding of AISI 1045 hardened steel are investigated. These nanofluids were synthesized by submerged electro discharge process, exposed to ultrasonic agitation in the presence of Tween 20 as dispersant and sprayed in grinding position using minimum quantity lubrication system. The base fluid is an emulsion of canola oil and distilled water with vegetable oil acting as triglyceride agent. Convective heat transfer coefficients of different lubrication systems in grinding are measured using an innovative approach to better explore the cooling mechanisms involved in grinding process with or without the application of nanolubricants. The variation of grinding forces and sub-surface temperature of workpiece are recorded at different lubrication conditions. These parameters along with surface roughness, micro-hardness, and microscopic observations of ground surfaces are employed to evaluate the performance of synthesized nanofluids as lubricants in grinding. The results show that the synthesized nanofluids are effective in reducing the grinding forces and temperatures especially in extreme machining conditions. Better surface integrity of ground parts is observed in all grinding conditions through the application of CuO nanofluids as lubricant in minimum quantity lubrication system.

Description: This research proposes an effective plane magnetic abrasive finishing (MAF) process which was combined with electrolytic process in order to improve machining efficiency of traditional plane MAF process. The new plane finishing process can make surface of workpiece to be planarized and softened through formed passive films from electrolytic process. Meanwhile, the passive films are removed by magnetic brush-generated mechanical processing force to achieve efficient precision machining. This finishing process is called electrolytic magnetic abrasive finishing (EMAF). In this research, we have developed a novel machining tool of compound magnetic poles and electrodes, which is able to achieve two different processes. The SUS304 stainless steel plane is used as workpiece. In order to select electrolytic finishing time for EMAF process, the investigation of electrolytic process has been carried out before EMAF process. Then, the comparative experiments of EMAF process and MAF process have been conducted in order to investigate the effect of EMAF process. The experimental results show that EMAF process can a little obtain higher quality surface, and machining efficiency is improved by about 50%, which compared with that of traditional plane MAF process. Furthermore, the surface roughness can be reduced to 30.94 nm R a from original roughness of 393.08 nm R a in 40 min by the EMAF process.

Description: A novel pulsed metal active gas-tungsten inert gas (PMAG-TIG) twin-arc tandem welding process is applied to make stable back beads in the first layer weld during one-side multilayer welding without backing plate. The effect of different arc distances on the arc plasma behavior, molten pool flow pattern, and back appearance of root welding during the twin-arc tandem welding was studied. Results indicated that when arc distance is about 22 mm during the welding process, about 30% heat energy of the arc heat is utilized to melt the root face of base metal, and the rest heat energy acts on the molten pool. In this condition, the temperature distribution of the molten pool is appropriate, the flow of the front edge of the molten pool is suitable, the back appearance is continuous, stable, and uniform, and the back reinforcement and weld width is moderate. When arc distance is about 17 mm, more arc heat energy is utilized to melt the root face, the fluidity of the front edge of the molten pool is stronger, which leading to the back reinforcement is relatively larger. While arc distance is about 27 mm, less arc heat acts on the root face, the fluidity of the front edge of the weld pool is weak, resulting that in the back reinforcement is relatively small. This twin-arc tandem welding process is a new welding process giving high quality and efficiency in root welding for medium or thick plates.

Description: Usage of high-strength steels with limited bendability in conventional air bending is not obvious due to the deformation limits of these materials. An attractive solution for deformation reduction is the utilization of large radius punches. The bending process for large radius tooling is dissimilar to conventional air bending, due to the presence of the multi-breakage phenomenon. This phenomenon has been observed by many researchers, but understanding of the influencing parameters is limited. Multi-breakage poses a serious obstacle, since it changes the loading scheme from the typical three-point to four-point bending. In this contribution, an extensive experimental exploration of large radius bending leads to conclusions on the influence of tool dimensions and material characteristics. Air bending experiments have been performed for five materials, four thicknesses, four punch radii, and four die openings. Based on the observed force measurements, the process can be defined as large radius bending when the ratio punch radius/die opening is larger than 1:4. Trends for the influencing parameters of the measured data can be used for further investigation of large radius air bending.

Description: Friction spot welding has become an excellent alternative to produce dissimilar joints in a fast and reliable way. This paper investigates the microstructure and the mechanical behavior of friction spot welded AA6181-T4/Ti6Al4V dissimilar joints produced by two different tool rotational speeds, 2500 and 3000 rpm, previously demonstrated to be the welding parameter with the most influence on the mechanical performance of these joints. Temperature profiles indicated that tool rotational speed directly affects the process temperature and, consequently, the metallurgical reaction taking place at the joint interface. Higher temperatures (3000 rpm condition) resulted in a complex and cracked Ti/Al interface because of the local melting of the aluminum plate. In contrast, by decreasing the process temperature (2500 rpm condition), a continuous thin TiAl 3 layer was observed, increasing the lap shear resistance of the joints. Moreover, the local Von Mises strain distribution of a sound joint under lap shear was successfully associated with the different stages of a typical force–displacement curve and used to elucidate the fracture evolution. Lastly, the fatigue behavior of the joints indicated that FSpW dissimilar welds exhibited a better performance than FSpW aluminum similar joints.

Description: Twin-belt-cast (TBC) strip is offered as forging stock for relatively flat, 2-dimensional forgings such as wishbone suspension. When forged, the fragmented eutectic cells of the TBC blank and the very fine precipitates are aligned in the forging direction with a section grain structure where much of the section is predominantly fibrous. The fibrous grains of the forged component undergo recrystallization and grain growth and are finally replaced by elongated grains in the plastic flow direction during solution heat treatment. Selection of the solutionizing temperature is claimed to be critical. The yield and tensile strength, elongation and hardness all decrease steadily with increasing solutionizing temperature due to grain coarsening. However, both the static and dynamic mechanical properties of the TBC EN AW 6082 blank compare favourably with the extruded forging stock, in spite of coarse grains across the entire section of the forging. After all, both suffer from coarse grains on the surface of the forging. It is thus concluded that the TBC EN AW blanks can be used for the manufacture of relatively flat, 2-dimensional automotive parts such as wishbone suspension components.

Description: Productivity is a key-factor for companies manufacturing parts and sets to the automotive industry. Automation plays an important role in this matter, allowing development of entire manufacturing cells without the direct need of workers. Even in countries where the labour cost is relatively low, it becomes necessary to improve the level of automation applied to manufacturing cells and reduce the dependence of the human labour unpredictability, also increasing the quality and reducing the costs. This case study was developed based on an industrial request in order to improve a semi-automatic cell devoted to seat suspension mat manufacturing. The original cell allows several automatic operations but it needs two workers for two specific operations not considered in the initial design. Thus, new concepts of wire feeding and manipulation were developed in order to allow a better material flow throughout the cell. The new cell was designed and built with success, allowing to obtain a full-automated system, which leads to a better productivity and reliability of the manufacturing process.

Description: Laser forming technology is widely applied in the forming of plates with advantages of high efficiency, die-less, and absence of tools et al. In the forming process of the panel with crossed reinforcing bars (PWCRB) with the integral continuous scanning strategy (ICSS), the twisting phenomenon occurred. This was induced by the buckling of the middle stiffener. The deformation behavior of the panel when formed with the ICSS was studied through numerical simulations. The results showed that the stress and strain were inconsistent along the scanning line which was induced by the inconsistency of the thickness along the scanning line. As a result of that, a consistency-deformation scanning strategy (CDSS) was proposed and its influence on the forming of the panel was studied in simulations. The results showed that the stress and the strain tended to be consistent, and the residual stress of the middle stiffener decreased so as to avoid the buckling of the middle stiffener as well as the twisting phenomenon of the panel. Both the experimental results and the numerical results showed that the PWCRB could be formed with the strategy efficiently.

Description: This paper presents a review on ultrasonic-assisted grinding (UAG) of advanced materials, specifically investigating the effects of ultrasonication on material removal rates (MRR), grinding forces and energy, tool wears, wheel loading, residual stress and surface/subsurface damages. It compares the performance of UAG of ceramics and super alloys for biomedical and aerospace applications, with the performance of the conventional grinding (CG) techniques. The effects of the UAG process parameters on the MRR, grinding ratio, tool life, residual stresses and surface/subsurface damages were also investigated. Studies on the performance of the UAG process in the machining of brittle and ductile materials have shown that the introduction of the ultrasonic system to the grinding process helps to increase the material removal rates significantly, and consequently reduces the surface roughness, grinding forces and subsurface damages. The self-sharpening phenomenon found in the UAG process was realised to be responsible for the improved machining performance of the UAG process. Furthermore, the application of biodegradable lubricants (vegetable oil based) to the grinding process was also found to improve the machining performances of the UAG process, achieving almost the same performance as the non-biodegradable lubricants. As such, the use of the biodegradable lubricants in the grinding process was encouraged due to its economic benefits, and environmental friendliness.

Description: Two-component injection moulding is a manufacturing process used to combine polymers with different properties within a single product. The process is often used to combine thermoplastics of different colours or to combine thermoplastic elastomers with thermoplastics to create hard and soft areas. In this study, a two-component injection moulding process is proposed for combining thermoplastics with thermoset rubbers. This poses technological challenges since rubbers require a heated mould (160–200 ∘ C) for the rubber to vulcanise whereas thermoplastics need a relatively cold mould (20–100 ∘ C) for the polymer to solidify. The mould used for this study is equipped with thermally separated mould cavities and allows to reverse the injection sequence of the two materials. It was found that the optimal sequence is to inject the thermoplastic first, followed by rubber, and that the mould temperature at the interface during the vulcanisation of the rubber is a critical process parameter. Too low mould temperatures at the interface result in long vulcanisation times and poor adhesion, whereas higher temperatures at the interface both decrease the vulcanisation time and increase the adhesion strength. However, when the temperature is too high, the adhesion strength decreases again due to gas bubbles at the interface released during the vulcanisation process.

Description: MQL and dry processes are becoming the most important issues in future manufacturing. Reducing or completely eliminate the lubricant can improve machining performances, air quality and reduce the machining costs. The coolant used in MQL should be environmentally friendly. The flow rate should be also optimized in order to enhance the machining performance and reduces the particles emission. Our research study was conducted in order to optimize the dry and the MQL processes. It has been found that the MQL process can reduce the cutting forces, friction and wear compared to the dry cutting. Chip morphology shows that the use of the coolant during MQL process embrittles the chip. However, in particular situations, the dry process can be competitive compared to the wet or the MQL processes. In this paper, an investigation study was carried out on the performance of MQL (Minimum Quantity of Lubricant) and dry high speed milling of three kinds of aluminum alloys 7075, 6061 and 2024. Four different flow rate of mist are tested during MQL machining processes. The effects of cutting speed, lubrication mode and material on the part quality were investigated. The machining performance is evaluated according cutting force, particle emission and the surface finish. Experimental results showed that the MQL milling can be interested in terms of force or surface finish but if the particle emission is considered the dry machining will be better. For the different lubrication modes at very high speeds, the results seem to converge. In this case, the dry machining should be advantageous.

Description: Engineering parts usually deviate from their intended shapes during their manufacturing due to the inaccuracies of machine tools, deformation of various elements of machine tool, cutting tools and workpiece. Resulting geometric errors affect the functionality and assembly of the parts significantly. This demands a reliable strategy to accurately assess the errors during the final part quality inspection. Among all the geometric features, circular feature is very common on the majority of the engineering parts. Hence, the measurement and evaluation of circularity with a high degree of accuracy are of utmost importance. In the present work, a hybrid approach is proposed to accurately evaluate the circularity error. This approach comprises a least squares method (LSM) and a novel probabilistic global search Lausanne (PGSL) technique. The LSM is used to reduce the search space initially. Within the reduced search space, the PGSL performs efficient, fine and global search. In the process of establishing minimum zone circles to the measured data of the circular features, the proposed approach dynamically updates the probability distribution function of the circularity parameters continuously. The update procedure ensures that the probability of moving towards the potential optimal solutions is increased. The algorithm has been tested using several benchmark datasets for its generalization capability and robustness. The proposed strategy is found to be efficient in yielding accurate results. Therefore, the algorithm can be implemented in computer-aided circularity measuring instruments in order to minimize acceptance of bad parts and rejection of good parts.

Description: The online sensing system provides the possibility for quick variation source identification of the assembly process. However, owing to the cost and time limit of the process, the sensor locations and sensor number for variation source identification are limited. The causal network method considering multi-source information is developed to assist identifying root causes of the dimension variation. Based on the proposed method, the diagnosis ability is evaluated, and then the minimal feature number and optimal measurement features are selected based on a sensor optimization algorithm. However, the random sampling uncertainty caused by insufficient sample size may affect the estimation accuracy of observation nodes and thus the misidentification rate of variation sources. By using Monte Carlo simulation, this paper evaluates sampling uncertainty of different sample size. Furthermore, by using probabilistic reasoning method with uncertain evidence, i.e., virtual evidence, the effect of sample size on the correct identification rate is analyzed. A dash panel case study is provided to illustrate the optimal feature selection procedures and the robustness to the sample uncertainty.

Description: A three-dimension (3D) finite element (FE) end milling model with equivalent homogenous material (EHM) model, which was drawn from the quasi-static and SHPB (Split Hopkinson pressure bar) tests, has been developed by using ABAQUS/Explicit in order to describe the machining process of SiC p /Al6063/30P composites. The model is verified by milling experiments and it is found that the predicted milling forces at different combinations of feed rate and rotation speed are consistent with those in milling experiments, and the prediction error of the peak value of F y and F x can be controlled within 20%. Moreover, the general shapes of the predicted chips are very similar to the experimental ones, but the application of EHM material model leading to the limitation of the simulated chip morphology such as cracks on chip contact surface and free surface caused by the existence of hard SiC particles cannot be described. Hence, further microstructure-level 3D FEM model which can reveal the interactions between particles and matrix and their effect on the chip formation mechanism of SiC p /Al6063composites becomes very necessary.

Description: Surface and subsurface damages appear inevitably in the grinding process, which will influence the performance and lifetime of the machined components. In this paper, ultra-precision grinding experiments were performed on reaction-bonded silicon carbide (RB-SiC) ceramics to investigate surface and subsurface damages characteristics and formation mechanisms in atomic scale. The surface and subsurface damages were measured by a combination of scanning electron microscopy (SEM), atomic force microscopy (AFM), raman spectroscopy, and transmission electron microscope (TEM) techniques. Ductile-regime removal mode is achieved below critical cutting depth, exhibiting with obvious plow stripes and pile-up. The brittle fracture behavior is noticeably influenced by the microstructures of RB-SiC such as impurities, phase boundary, and grain boundary. It was found that subsurface damages in plastic zone mainly consist of stacking faults (SFs), twins, and limited dislocations. No amorphous structure can be observed in both 6H-SiC and Si particles in RB-SiC ceramics. Additionally, with the aid of high-resolution TEM analysis, SFs and twins were found within the 6H-SiC closed packed plane, i.e., (0001). At last, based on the SiC structure characteristic, the formation mechanisms of SFs and twins were discussed, and a schematic model was proposed to clarify the relationship between plastic deformation-induced defects and brittle fractures.

Description: The growing demand for products that resist in environments considered severe has stimulated in the last years series of researches. They have the objective to improve the properties of materials and their processing and applications. Among the metals commonly used in extreme temperature and corrosion, there are the nickel superalloys, in particular Inconel 718. However, the same thermal, mechanical, and metallurgical properties, which make it a material of great applicability, also characterized as one of the metals of low machinability. Given that the market trend is increasingly using special materials such as superalloys, a detailed study about the machining of these materials is strategic and it is necessary that companies constantly seek to improve their processes. Besides that, the attention to environmentally safe processes from society and governmental regulation is growing. Therefore, this paper evaluated the performance of different conditions, dry and wet, on external longitudinal turning of Inconel 718 with ceramic tools, identifying the mechanisms and types of predominant wear. For both conditions, notch wear was the main type observed in the experiments and it was more evident during dry machining.

Description: Research on computer-aided design for machine tools has been in the interest of many researchers for a long time and generated several new methods for different engineering applications. This paper introduces a case-based reasoning (CBR) method combined with SolidWorks application programming interface (API) for special purpose machines (SPMs). It presents an integrated system with focusing on the indexing and retrieval process for the design cases. An indexing mechanism was developed for SPMs, and two retrieval stages were applied to retrieve the optimum case. An illustrative example is included to demonstrate the proposed method and how this method combined with SolidWorks API will accelerate the design process for SPMs.

Description: Numerical simulation and experimental methods were conducted to study the non-uniform thickness during hydroforming of a rectangular cross-sectional component by using a bent tube, which is thickened inside and thinned outside. A method of changing the contact sequence of the tube to the die surface is proposed to improve thickness distribution of hydroformed part. There are four contact sequences, Side-and-Side (SS), Side-and-Fillet (SF), Fillet-and-Side (FS) and Fillet-and-Fillet (FF), that are proposed through the preform shape for a rectangular section. The effect of contact sequence on thickness distribution was studied. The results show that SF or FF contact sequence makes the fillet corner contact with the die surface first and suppresses the further thinning in hydroforming. On the contrary, SF or SS contact sequence makes the straight side of the bend inside contact with the die surface first and benefits the full deformation of the thickening region in hydroforming. Among them, the SF contact sequence is the best for the uniformity of thickness, and SF and FF contact sequences are useful to ensure the minimum thickness of the section and help to avoid cracking defects. On the basis of it, two contact sequences, SS and FF, were applied to an instrument panel bar, respectively. There is a cracking defect in the circular section for the SS sequence, while there is no defect in the straight and circular sections for the FF sequence. And the sound part is successfully developed and applied to the assembly of the instrument panel bar of Chrysler 300C car in mass production.

Description: Conventional drilling (CD) which is known by two constant rotary and linear motions causes some problems in drilling of materials such as high thrust force, poor surface quality, and rapid tool wear. To get rid of these problems or at least minimize them, a promising technology has been employed in the recent years, where vibrations usually with low amplitude and high frequency are applied to the direction of feed motion results in a time-dependent velocity between drill tip and workpiece. This paper focuses on the design of a vibratory tool following by experimental and numerical approaches to study the influence of longitudinal ultrasonic vibrations on drilling of aluminum alloy 7075. Experimental part is a comprehensive exercise to design, fabricate, and test a system equipped with different instruments to work in desired conditions. Experimental results are supported by a finite element method to better comprehend what is happening in cutting process when ultrasonic vibrations are added. The achieved results prove that using ultrasonic-assisted drilling (UAD), the machining ability of drilled aluminum workpiece can enhance significantly. Improvement of up to 40% for drill circularity and a reduction of up to 37% in thrust force were achieved.

Description: High-leveled surface integrity which is significantly affected by processing parameters is required for machining military and aviation component. This paper firstly introduces the material (rolled Elgiloy), structure (with thin-walled slot), and machining method (micro-milling) of this component. To present surface structural traits, three-dimensional (3D) fractal dimension Ds based on variance method is proved to be a good index, compared with surface roughness. The micro-milled surface quality and structural characteristics are found to be different in various areas. The feed per tooth is revealed as the key factor that affects surface quality and complexity. Based on two-dimensional (2D) fractal method, trend of surfaces structural traits are evidently observed and found closely related to this processing method. These milled surfaces are then evaluated to be of good isotropy, considering the variance of slop and curvature of profiles. And surface anisotropy is found more sensitive to milling depth. With wavelet transform and 2D fractal method, key spatial frequency bands that affect anisotropy and complexity of the surface are revealed, respectively. The present analysis reveals the relationships between various areas of surfaces, anisotropy, and processing parameters in depth and helps to choose reasonable milling parameters for improving surface quality and complexity.

Description: This paper describes a new model for predicting micro-pattern deformation in rolling-based surface texturing. With the assumption that the micro-rolling process is essentially quasi-static at relatively low speeds, the model was deduced from the Hertzian theory-based approach of Johnson et al. and experiment data. In particular, to address uncertain factors in micro-rolling contact, a transformation coefficient γ was proposed in the static model to shift from an indentation to a rolling process and was investigated empirically. However, deformation of micro-patterns in rolling contact includes both elastic and plastic phases; thus, an appropriate combination of theoretical and empirical analyses of micro-elastic-plastic deformation was used to establish the static model. A surface deformation constant, ε , was used in an analytical model of elastic-plastic behavior to determine the relationship between the plastic deformation of steady patterns and contact depth. The constant ε was investigated and calculated from experiments and the theoretical model. Subsequent experimental results confirmed the feasibility of the model and demonstrated an incremental plastic proportion, and correspondingly, a decremental elastic proportion when increasing the rolling force. Finally, an elastoplastic ratio, ε e , is presented for estimating elastic and plastic portions distinctly. A nearly linear relationship between ε  and  ε e was found in this research.

Description: Servo mismatch, which affects positioning accuracy in computer numerical control (CNC) machine tools, is an important source of error. Dynamic measurements of simultaneous movements in two axes are essential in determining servo mismatch. A circular test using a double ball-bar (DBB) is used commonly to assess such errors. However, servo-mismatch measurements of some machine tools, such as miniaturized machine tools, remain difficult due to structural restrictions of the measuring devices. In this study, a technique for servo-mismatch measurement via a bi-directional circular test using a laser tracker is described. The laser tracker is easy to set up experimentally and has fewer measuring range restrictions than other measuring devices. In order to ignore the effects of quasi-static errors, a bi-directional circular test is conducted using the laser tracker. Additionally, a compensation procedure, with a proportional equation, is proposed. The validity of the technique described was confirmed by comparison with the DBB result. In a machining test after servo-mismatch compensation, by adjusting the position loop gain, the roundness of a cylinder part was improved by ∼47.9%.

Description: In this paper, an inverse matching method with a foil/workpiece thermocouple is used to determine the global heat flux distribution and energy partition in the workpiece when grinding under oil lubrication. Low-pass filtering and sampling frequency of the temperature measurement in the inverse matching method are of particular importance, given fast variations of the heat flux at the wheel-workpiece interface. In the inverse method, low-pass filtering and sampling have a negligible influence on the average heat flux but not on the maximum heat flux. The mean heat flux in the region of positive heat flux and the partition ratio are determined under no-burn and burn grinding conditions. The new heat flux distribution estimated by a scalene triangle in the grinding zone and an exponential function in the convective cooling zone is in very good agreement with the test temperature profiles.

Description: Diamond-coated cutting tools are known to machine complex materials with many benefits associated with the generation of lower temperatures between contact surfaces. However, the complexity associated with machining exotic materials at the micro-scale eludes many researchers who study phenomena pertinent to the development of new processes for novel micro-structured materials. The study investigated the use of a Lagrangian-Eulerian-formulated finite element program to analyze chip formation and thermal effects when micro-machining Ti6Al4V titanium alloy used for medical device applications. For the simulated machining conditions described in this paper, chip formation occurred when F C / F T 〉1 and burr formation occurred when F C / F T 〈1. In addition to the force conditions, when the ratio of feed per tooth to tool edge radius is approximately unity ( f tooth / t r ∼1), the micro-machining process forms chips. When the ratio is decreased to equal 0.5 ( f tooth / t r  = 0.5), chip formation and burr formation exists simultaneously. However, when the ratio approaches an approximate value of 0.3 ( f tooth / t r ∼0.3), burr formation is dominant. The study also provides an insight into the thermal effects of micro-machining that shows how vertical filament chemical vapor deposition (VFCVD)-coated tools maintain the integrity of the surfaces of the material as a function of simulated machining parameters. In conclusion, the computational analysis is compared with practical micro-machining results reported in the literature.

Description: Ni-based superalloys, like Inconel 625, are commonly used in different industrial sectors, like aerospace and power generation. The performance of Inconel 625 could be improved by the addition of ceramic particles like Cr 3 C 2 . The high costs involved using metal matrix composites could be reduced applying them as superficial coatings onto a cheaper material with limited performance. Laser cladding technology was selected in this work among the different possible methods to deposit coatings. Based on previous works regarding to laser cladding deposition of Inconel 625 clads, a process parameter selection to obtain Inconel 625-Cr 3 C 2 clads onto a steel substrate has been reported. A design of experiments was used to select the combination of parameters and their values for the deposition process. The mechanical performance of the coatings’ matrix was analysed and compared with the results previously reported for an unreinforced Inconel 625 coating, deposited in similar way. The microstructure of the coatings was also studied and correlated with the mechanical behaviour.

Description: Residual stresses generated during hot stamping have a significant effect on the mechanical properties and dimensional stability of aluminum alloy sheet components. What is more, few studies have paid attentions to the effects of hot stamping parameters on residual stresses and the methods of reducing residual stresses during hot stamping of aluminum alloy plates with thickness around 5 mm. Hence, in this study, the effects of forming temperature, blank holder force, die entrance radius, die corner radius, and local thickening on the residual stresses of square cups were studied, by conducting both finite element simulations and experiment investigations of the hot stamping of 2024 aluminum alloy plates. The results showed that the residual stress distribution is not uniform through the thickness. Within the range of process parameters investigated in this study, increasing the forming temperature, blank holder force, and die corner radius or decreasing the die entrance radius all lead to lower values of residual stresses. Compared to flat plates, local-thickened plates can significantly reduce the residual stresses in hot stamped square cups, which is attributed to the metal supplement mechanism at the thickened locations. When the side length of the square-ring-shaped convex rib of the plate is equal to the punch width and the convex rib facing downward, lower residual stresses in square cups are obtained. The established residual stress calculation model is capable of describing the residual stress distribution in the bottom circular arc of hot stamped square cups.

Description: The profile of drill flute has a great influence on the drilling performance of micro-drill. It is promising to obtain a desired flute profile with a standard wheel by adjusting the wheel position parameters during the grinding process. To investigate the flute profile characteristics under different wheel position parameters and its effect on the drilling performance, this paper presents a method for modeling and optimization of the micro-drill flute considering the wheel installation angle and the offset distance from the wheel origin to the drill blank origin. Based on this model, the flute profile of micro-drill is numerically simulated by MATLAB software firstly, and then, the 3D model of micro-drill with different flute profiles is established by UG software. Finally, the micro-drilling process on 304 austenitic stainless steel is simulated by DEFORM software, and the chip morphology and the drilling force are analyzed and discussed. The results show that the wheel installation angle has an obvious effect on the flute profile and its radial rake angle and flute width, and the wheel offset distance only influences the flute width evidently. The micro-drill with flute ground by smaller wheel installation angle owns straighter cutting lip shape and larger chip evacuation capacity, and its thrust force and torque are smaller than those of other micro-drills. Moreover, spiral chip is generated due to the intense side curl and up curl of the chip, resulting in the easiness of the chip removal. However, for the micro-drills with flute ground by larger wheel installation angle, the chip morphology is string and the drilling force is larger. At last, the mathematical model of the drill flute and its numerical simulation result are validated by experimentally fabricating the micro-drill flute. Then, the optimized micro-drill is manufactured by a six-axis computer numerical control (CNC) grinding machine, and its flute profile is fabricated using a standard conical grinding wheel with a smaller wheel installation angle.

Description: Quality function deployment (QFD) is a consolidated management tool for supporting the design of new products/services and the relevant production/supply processes, starting from the so-called voice of the customer (VoC). QFD includes several operative phases, ranging from the VoC collection to the definition of the technical features of production/supply processes. The first phase entails the construction of the so-called house of quality (HoQ), i.e., a planning matrix, which translates the customer requirements (CRs) into measurable engineering characteristics (ECs) of the product/service. One of the main goals of this phase is the definition of relationships between CRs and ECs, and the prioritization of these ECs, taking account of (i) their relationships with CRs and (ii) the importance of the related CRs. Given that data are collected from customers through questionnaires or interviews, both of these inputs are based on linguistic/ordinal scales. In the traditional approach, represented by the independent scoring method (ISM), ordinal data are arbitrarily enriched with cardinal properties. The current scientific literature encompasses a number of alternative approaches but, even for most of them, cardinal properties are mistakenly attributed to data collected on ordinal scales. This paper proposes a method based on a consolidated ME-MCDM (multi expert / multiple criteria decision making) technique, which is able to perform the EC prioritization without incurring in the aforementioned issue. This method is able to aggregate data evaluated on ordinal scales, overcoming controversial assumptions of data cardinality and avoiding any arbitrary and/or artificial “scalarization” of the data. On the other hand, its application is relatively simple and intuitional, compared to other proposed approaches alternative to the ISM, which often are conceptually complicated and difficult to implement. Furthermore, the proposed method can be effectively used when both CR importances and relationship matrix coefficients are rated on different ordinal scales and, being easily automatable, it can be effortlessly integrated into existing QFD software applications. In the paper, after a general description of the theoretical principle of the method, several application examples are presented and discussed.

Description: The article covers a mathematical model of a temperature distribution in the three-layer metal composite structures when grinding their working layers. The computer program TEMSS, created on the basis of thermal models, allows calculation of all the characteristics of the temperature distribution in the layers of the metal composite structure, depending on the system structure, material properties of its layers, grinding and machining conditions, and duration. The work establishes the adequacy of the developed mathematical model of the temperature distribution when grinding the metal composite systems. The article covers the analysis of standard metal composite systems with Loctite, Chester molecular, and Devcon polymers on the basis of the temperature distribution model, revealing the influence of lamination on the nature of the temperature distribution. Critical temperatures are defined that determine the occurrence of thermal grinding defects in the metal composite system, including their dependencies on processing conditions and the system structure. Thus, it is found that when grinding a working steel layer of the composite system using the standard grinding conditions recommended in the reference handbooks for steel workpieces, the temperature in the working and polymer-composite layers, as a rule, exceeds the threshold values for these materials.

Description: Single pass autogenous butt welds, without detectable volumetric defects, were manufactured by electron beam welding 90-mm-thick UNS S41500—a low carbon 13% Cr-4% Ni martensitic stainless steel typically used for hydroelectric turbine applications. The mechanical properties of the joints were evaluated in the as-welded condition by tensile testing, Charpy V-notch testing, and bend testing. Specifically, static tensile loading was conducted on samples extracted transverse and longitudinal to the weld seam. To determine the impact toughness of the electron beam welded joints, the Charpy tests were conducted on samples with V-notch roots located in the fusion and heat-affected zones at −18 °C. The yield strength, ultimate tensile strength, elongation and toughness of the electron beam welds were found to more than adequately meet the minimum acceptance criteria specified in ASME section VIII and IX. Also, the formability of the welds, examined by bend testing, displayed no discontinuities on the tension side of the bent joints. These promising mechanical properties determined for the as-welded UNS S41500 stainless steel offer considerable prospects for industrializing the electron beam welding process.

Description: In this study, we propose a new approach to investigate the influence of the grinding process parameters on the friction coefficient of the ground surface when in contact with another surface. This is achieved through the implementation of a physics-based model capable of predicting the friction coefficient. The model is based on hydrodynamic lubrication theory, solving a special case of the Navier-Stokes equations (Reynolds equation). The model will provide more insights to help optimize the grinding parameters and therefore surface texture, thus achieving the desired product functionality in term of tribological behavior. The model is being validated using reported experimental data. A case study on the influence of grinding wheel speed on the surface roughness and tribological behavior is performed. Based on the predicted results, we report an average friction coefficient in the transverse direction lower than the longitudinal. The proposed predictive approach demonstrates capacity in predicting the impact of grinding wheel speed on the friction coefficient, hydrostatic pressure, and average film thickness for a defined contact condition, hence more insights on the tribological functionality of a ground surface.

Description: In this study, influence of added linear vibration of cutting tool on the performance of rotary turning of AISI 4140 steel is investigated. Experimental tests are carried out at different cutting and tool rotary speeds by using special equipment for ultrasonic assisted rotary turning. The results of surface roughness, cutting force, and tool wear obtained during vibratory-rotary cutting are compared by the values of conventional and rotary turning. At the end, it is shown that lower displacement of workpiece in the radial direction, decrease of tool rake angle, and producing cooling cycle during disengagement time in vibration cutting cause lower wear distribution along the circumference of cutting tool. As a consequence to that, a significant reduction in surface roughness and cutting force is observed compared to the conventional and rotary turning. Besides, effect of variations in tool rotary and cutting speeds on output parameters are evaluated.

Description: Tactile sensors are key components for a robot hand system, which are usually used to obtain the object’s features. The use of tactile sensors to obtain information from the objects is an open topic of research. In this paper, a new strategy for in-hand extraction of object’s properties and for control of the interaction forces with robot fingers, mainly based on tactile data, is presented. The scope of this strategy is to grasp and manipulate solid objects, including rigid and soft bodies. Assuming that the hand is in an initial configuration in which the object is grasped, the properties’ extraction approach is executed. After the extraction of properties is finished, the object can be classified in regard to a general body listing: rigid body, soft elastic body, or soft plastic object. Once the object is classified, for in-hand manipulation tasks, the contact points between the object grasped and the fingers are maintained using the information given by the tactile sensors in order to perform manipulation tasks. Each task is defined by a sequence of basic actions, in which the contact points and applied forces are adapted depending on the action to be performed and the estimated features for the object. The presented approach tries to imitate the behavior of human beings, in which the applied forces by the fingers are changed when the human estimates the rigidity of a body and when the fingers react to unexpected movements of the object to keep the contact points.

Description: In present research, micro-milling of heat-resistant stainless steel (12Cr18Ni9) is conducted with the purpose of revealing influence mechanism of cutting tool edge radius and cutting parameters on specific cutting energy. In order to clarify the relationship between specific cutting energy and the geometrical characteristics of the cutting tools as well as cutting parameters, a newly designed experimental method is put forward, thereafter, the evolution rules of specific cutting energy along with cutting parameters is researched in detail. Furthermore, a prediction model of the minimum chip thickness is built by using fuzzy logic method based on experimental data, objective to optimize cutting parameters during micro-milling of 12Cr18Ni9, good agreements are achieved between predicted results and experimental results in verification tests, which means the specific cutting energy can be well controlled with the parameter recommended by the constructed model. The above research has great significance in improving tool life and machining quality.

Description: This paper presents a variant of the traditional ‘mortise-and-tenon’ joint, which has been used for thousands of years by carpenters and blacksmiths to connect wood or metal parts. The new proposed joint is utilized to fix longitudinally in position two metal sheets (or plates) perpendicular to one other by sheet-bulk metal forming, at room temperature. The development is performed by means of a combined finite element and experimental investigation focused on the identification of the major process parameters and on the understanding of their influence on the overall joining feasibility. Destructive testing is carried out to characterize the performance of the new proposed joint, and an analytical expression is provided to determine the maximum tensile force that the joint can safely withstand.

Description: The paper investigated how hydrogen, introduced via thermal diffusion, influenced the formation and morphology of chips formed by cutting Ti-6Al-4V alloys. The chips’ microstructure and characteristics were studied by using optical microscopy (OM), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Experimental results demonstrated that with an increase in plasticity, the lamellar chips transformed to saw-tooth chips. Metallurgical analysis suggested that the saw-tooth chips formed because of thermoplastic instability caused by large plastic deformation. In contrast, the lamellar chips formed because of crack initiation.

Description: Current development in the manufacturing of aircraft composite parts has greatly utilized the prepreg materials in the autoclave moulding process in producing exceptional quality of laminates. Nevertheless, several issues related to the manufacturing quality of the complex-shaped laminates are still found unresolved, where the thickness uniformity, resin distribution and fiber wrinkling have been mostly regarded as the critical issues that contribute to the reduced mechanical properties and life span of the structure. A review on the contribution of the processing parameters towards the manufacturing defects of the aircraft complex-shaped laminate is critically presented. The discussion included the effects of the parameters on the defect formation during the sub-processes involved. It was found that the defects occurring were substantially affected by various factors, including mould selection, material characteristics, bagging configuration, etc. Subsequently, the correlation between the processing parameters and the related defects was thoroughly investigated, in which several findings are decisively proposed.

Description: In this paper, we propose a method to deal with the control of an electroplating line without stopping the production. The considered system is running in repetitive functioning mode, and it is modelled by a P-time event graph. The main objective is to switch the number of parallel resources to maintain a resource while the production is assumed to be always running. So, two functioning modes appears: normal and maintenance modes. Each mode is described by a state space model written in the standard algebra and a global model corresponding to a switching system which is a class of hybrid systems is obtained. Using model predictive control technique, stabilizing state feedback gains are computed over an infinite horizon respecting the time constraints while maintenance is performed.

Description: In the process of micro end-milling, the micro tool axis is not the same line of the spindle axis due to the eccentricity of the tool-holder-spindle assembly, which is called tool runout. Tool runout has significant effects on cutting force variation, which can lead to higher peak forces and uneven tool wear of the cutter. Hence, a runout model must be included in a cutting force modeling to simulate accurate cutting force during micro-milling process. In this paper, the method for modeling and simulation to measure a runout of tool-holder-spindle in micro end-mill was developed. The simulated cutting force with regard to runout was compared with the measured cutting force. It is noted that they had similar variation pattern and closely matched amplitude levels. The result indicated that the effects of tool runout were predominant for the 0.9 mm diameter and at low feed per tooth.

Description: Towards the problem of closed space of Boring and Trepanning Association (BTA) drill, this paper presents a novel experimental method to evaluate BTA tool geometries, and a turning-based test is conducted to simulate drilling. The three inserts of BTA drill are replaced by the three turning inserts, the rotation of BTA drill is transformed by workpiece rotation in turning, the feed of BTA drill changes into the feed of turning inserts, and the cutting area per BTA insert is simulated by the cutting depth in turning. To implement the approach, three angles, consisting of edge inclination, flank angle and edge declination, are organised by a three-factor and three-level Taguchi experiment for each BTA insert, e.g. outside insert, centre insert and middle insert. Cutting force, chip patterns and chip curl radius are observed and measured to evaluate the insert geometries.

Description: Scheduling of jobs and resources on a shop floor is an ever green optimization problem. Job shop scheduling problem (JSSP) is an allocation of ‘n’ jobs on ‘m’ machines so as to complete processing of all jobs in a minimum possible time. The JSSP has been addressed by various direct, indirect methods, programs, and algorithms in the last 40 year of literature. This paper presents a new paradigm of invasive weed optimization which mimics the process of weed colonization and distribution to solve JSSPs. The algorithm had shown encouraging and promising outputs on standard benchmarking problems.

Description: Micro-ultrasonic sheet-metal forming using molten plastic as a flexible punch is a new microforming technology useful for manufacturing micro-stamped thin sheet metals. In this paper, we researched how time parameters influenced the forming replication ability of microchannel forming. Our experimental results show that the forming replication ability of the method was improved by extending the ultrasonic action duration time and maintaining pressure time. An appropriate ultrasonic action duration time was determined by assessing the melting time of the plastic powder used as a flexible punch; an appropriate maintaining pressure time was determined by assessing the coagulation time of the molten plastic punch. When the ultrasonic action duration time was 0.5 s and the maintaining pressure time was 1.5 s, the forming replication ability of the microchannel reached 97 %. With further increases in the time parameters, the forming replication ability stopped rising, and the forming method produced parts with defects at a lower forming efficiency. Through these experiments, we obtained a set of optimal process parameters for microchannel formation.

Description: Nowadays, the modeling and simulation of grinding have become powerful tools in predicting the process performance and work results. However, common simulations focus on material removal process of abrasive grains and neglect deformations of machine structure. The grinding quality can be influenced by various factors, of which the process-machine interaction results in often unpredictable effects, especially in the processing of hard-to-cut material. This paper proposes a simulation approach based on integrated process-machine model in plunge face grinding of cemented carbide. The approach synthesizes the interactive influence between machine dynamics and physical factors in grinding process. A virtual wheel model is built considering the stochastic nature of abrasive grains on the wheel surface, and the simulated forces and surface roughness are further predicted. The spindle-wheel structure is also modeled based on the finite element method. In order to implement the process-machine interaction, a coupled simulation by using self-developed interface is applied to accomplish data exchanges between different simulation environments. The simulation results are verified and found to be in good agreement with experimental results.

Description: A kind of Ti(C, N)/Al 2 O 3 composite cermet tool was prepared by microwave sintering. The cutting performance and wear mechanisms were investigated via high speed dry cutting of hardened steel 40Cr (AISI 5140) in comparison with those of two kinds of conventional cemented carbide tools YS8 and YT15. The optimal cutting parameters were obtained by orthogonal array and range analysis, in which the optimum objectives were material removal, surface roughness, and tool life. The results indicated that the optimal cutting parameters of the cermet tool were the cutting speed of 120 m/min, the depth of cut of 0.3 mm, and the feed rate of 0.1 mm/rev. Compared to the cemented carbide tools, the tool life of the cermet tool is 64.5 min, which is about 115.0% higher than YS8 and 168.8% than YT15. The average surface roughness is 1.27 μm, which is about 15.9% lower than that of the cemented carbide tools. The cermet tool shows much better cutting performance than those of cemented carbide tools. The failure mode of the microwave sintered Ti(C,N)/Al 2 O 3 cermet tool was micro-chipping, and the wear mechanisms were mainly abrasion wear and adhesive abrasion.

Description: Bent mandrel, which consists of non-axisymmetric curved surface (NACS), has been widely used as precise mold in automobile industry, shipping industry, and aviation industry. To improve the versatility and efficiency of turning method of the NACS with fixed rotational center, a machining method of non-axisymmetric curved surface using symbolic computation is proposed in this paper. A spiral tool path generation approach in non-axisymmetric turning process (NATP) is developed as well to deal with the error of part-to-part repeatability in existed machining model. The actual cutter-contact points are obtained from the approach of spiral sweep process using equal-arc-length segment principle in polar coordinate system. The tool offset, which is used to avoid the interference between tool and workpiece, is also considered in the machining model. In the NATP, the model of CNC lathe is established based on machine kinematics, and the inserted cutter is mathematically modeled considering both its geometrical model and the positioning of the insert. Depending on the spindle rotational angle, the synchronized control of X -axis, Z -axis, and C -axis is adopted to generate the tool path of the NATP. NC program has been generated using symbolic computation method according to the presented model, including calculation of cutter-location points and generation of 2D tool path of cutting process. With the approach of a bent mandrel taken as an example, the experiment results have verified that the machining method is appropriate for the NACS

Description: In order to achieve the restoration of the sprocket, it is significant to repair or modify the damaged sprocket by using an advanced surface treatment technique, such as the laser cladding process. In this paper, the Taguchi method was applied to conduct the experiment to optimize the process parameters for repairing a sprocket in the laser cladding process. The dilution was chosen to evaluate the quality of the cladding layer and the effect of the process parameters, such as the laser power, scanning speed, and powder feeding rate, with respect to the cladding layer geometry, and the dilution was investigated systematically. Then, using the optimized parameters, the sprocket was remanufactured and its surface profile characteristics, microstructure, and microhardness of the repaired sprocket were analyzed. The results show that the optimal process parameters (1000 W, 2.81 g/min, 1200 mm/min) obtained by the Taguchi method could realize the lower dilution. With the optimal parameters, the repair accuracy of the sprocket could reach 2.973 mm, which offers the machining allowance for machining of the sprocket. A white bright band observed at the interface shows that the metallurgical bonding was realized between the cladding zone and base metal. The microhardness of the cladding zone is higher than that of the heat-affected zone and base metal. Furthermore, the results reveal that the Taguchi method can effectively acquire the optimal combination of process parameters, and the laser cladding process exhibits good feasibility and effectiveness for repairing the machinery components with complex shapes.