ALBERT

Notes: One of the basic prerequisites for rational and high quality production of plastic parts is a tool layout tailored to the production process. To date, both design and construction have generally been based on values acquired by experience. This first, necessitates highly qualified personnel and second, involves what is frequently time consuming and costly finishing work. Experience acquired so far with computer-aided layout of injection molds shows that even a designer with little experience reaches the target more quickly and more reliably. At the same time he is able to draw on the results of intricate calculation and simulation methods which he was unable to apply in the past for reasons of time alone. This paper thus sets out the possibilities currently open and the experience available for computer-aided mold layout. The chief point of focus here is a system for the layout of injection molds. Working on from this system, however, the potentials for computer application are presented for blow mold- and foaming mold-design. After finding the mold principle, mold layout essentially divides up into two major areas, namely dimensioning calculations (CAE) and compilation of production documents (CAD). In dimensioning, the different functional elements of the mold are calculated. The aids that have been developed and the potentials of computer-aided dimensioning are presented with examples from the fields of rheological, thermal, and mechanical mold layout. Computer-aided rheological layout divides up into two steps. The first gives information on qualitative filling behavior (filling picture, flow paths) and the second provides quantitative results (pressures, shear stresses, temperatures). Computer-aided thermal layout similarly divides up into part steps. These are a rough overall energy balance, a rough layout of the tempering system, a segmented layout, and a homogeneity check, which involves simulating the temperature conditions in the mold by means of difference methods. When it comes to mechanical layout of the mold, programs are available for deformation calculations on basic cases and these will frequently be sufficient. For more complex cases of loading and deformation, a finite element program is used. Graphic data processing units can be used to supply extra facilities - first, to provide an aid for the simulation programs in dimensioning and second, to rationalize the compilation of the production documents. An illustration of a CAD workplace is given, incorporating the necessary computer configuration and peripherals. Compiling production documents is essentially a problem of variant design. The variants in this case are the individual components of the mold and a number of standardized accessories that can be called up as “standardized components.” The mold cavity, however, always has to be a free design. All programs are dialogue driven and are in a standardized manner so that even designers with no data processing experience can use the computer as an aid. The CAD/CAE system presented duly fulfils all these requirements. It allows the designer, at a single computer work station, to carry out both simulation and dimensioning calculations, to obtain information on material data, and to compile production documents on the basis of variant and free design. This provides the designer with a readily manageable aid and makes a considerable contribution towards improving the design result. Finally, the capacity of different computer concepts and the CAE/CAD/CAM systems on the market are discussed. For the future it will be possible to establish a computer-aided link between the different areas of design, from development of the molded part, via mold design and production, through setting the processing parameters of the injection molding machine.

Notes: Nach dem Pulverpackverfahren werden Diffusionsschutzschichten auf den Stahl 13 CrMo 44 (Werkstoff Nr. 1.7335) aufgebracht. Ihr Aufbau wird durch Aluminiumkonzentration in der Probenoberfläche, Schichtdicke und Oberflächenbeschaffenheit beschrieben. Es wird berichtet, wie diese Kenngrößen von Pulverzusammensetzung, Beschichtungstemperatur und Beschichtungszeit abhängen. In 16wöchigen Auslagerungen pulveraluminierter Proben bei 608 °C unter Schutzgas erfolgt nur eine geringe Abnahme der Aluminiumkonzentration in der Probenoberfläche und keine Schichtverbreiterung. Im Verlauf der Auslagerung bildet sich zunehmend eine neue Phase der Zusammensetzung Fe3Al in der Interdiffusionszone aus.

Notes: Coated pack aluminized low alloyed steels are known for their good resistance against high temperature corrosion up to 700 °C, where diffusion stability is still sufficient. In typical high temperature applications, coating and substrate are subjected to thermal fatigue. In this study the metallurgical stability of a coated, pack aluminized, low alloyed steel is reported. The specimens were cyclically quenched from 700 °C to room temperature or liquid nitrogen temperature respectively, to assess the importance of thermal shock severity on the kinetic of degradation. In particular, crack initiation and growth were studied. The dependence of microcrack densities upon numbers of cycles, cooling rates and specimen geometry is reported.

Notes: Zum Schutz vor Schwingungsverschleißschäden wurden Flachproben der Legierung Ti-6Al-4V mit metallischen Schutzschichten versehen. Dazu wurden die Proben mit Cu, Cr, V, Ti und durch einen Al/Cu-Verbund beschichtet. Die beschichteten Proben wurden dann in einer Reibkufenapparatur geprüft.Es zeigte sich, daß alle Beschichtungen außer dem Al/Cu-Verbund zu erheblichen Steigerungen der Probenlebensdauer bzw. -festigkeit führten.Wie rasterelektronenmikroskopische Untersuchungen ergaben, gelingt durch die Beschichtungen eine Trennung von Grundwerkstoff und Oberflächenfunktion, wodurch die Wirksamkeit der Beschichtungen von eher geringer Verschleißfestigkeit erklärbar wird.

Notes: Mit Hilfe des reaktiven Hochfrequenz-Magnetronkathodenzerstäubungsverfahrens wurden dünne Aluminiumoxidschichten auf Stahlsubstraten abgeschieden. Aufgrund der relativ niedrigen Substrattemperaturen (〈 etwa 250°C) zeigen die Schichten eine amorphe Röntgenstruktur.Messungen der Schichteigenspannungen, die mittels der Biegestreifenmethode durchgeführt wurden, zeigten, daß sowohl von der Schichtdicke als auch von Beschichtungsdruck und -leistung starke Einflüsse auf den Eigenspannungszustand ausgehen.Darüberhinaus konnten Abhängigkeiten zwischen Schichthaftungsverhalten und den inneren Spannungen der Schichten nachgewiesen werden.Neben dem Ritztestversuch diente das Ablöseverhalten der Schichten im Kerbschlagbiegeversuch als Haftungskriterium. Die Ergebnisse beider Verfahren befinden sich in guter Übereinstimmung.Einige der Schichten wurden ersten Verschleißuntersuchungen unterworfen. Die Schichten zeigten unter den gewählten Modellverschleißbedingungen ein gutes Verschleißverhalten.

Notes: The Community Bureau of Reference has organized a collaborative interlaboratory project to improve the analytical protocol for some specific chlorobiphenyls (CBs) within the European Community (EC). A series of test procedures were prescribed to optimize the gas chromatographic conditions for splitless and on-column injection, which substantially improved the quality of data. Important parameters included the initial column and injector temperatures and the choice of the polarity of the stationary phase. In a study with cleaned eel-fat extracts, coefficients of variation for reproducibility CV(R) ranging from 11 to 24% at the 0.04-0.3 mg/kg level per CB congener were obtained. No significant difference could be found between splitless- and on-column injection.

Notes: PVD-erzeugte Hartstoffschichten haben vor allem im Werkzeugsektor in den vergangenen Jahren verstärkt Eingang gefunden.Um die Beschichtung eines Werkzeugs oder Bauteils in geeigneter Weise gemäß den gegebenen Beanspruchungskomplexen optimieren zu können, ist es notwendig, genaue Kenntnisse über bestimmte Basiseigenschaften, wie Härte oder Haftfestigkeit sowie über die Wechselwirkungen zwischen den Abscheideparametern und den Schichteigenschaften zu gewinnen.Eine dieser Basiseigenschaften, die das Verhalten einer Schicht maßgeblich beeinflussen, ist deren Struktur. An gesputterten Aluminiumoxid-Schichten wurde die Schichtstruktur in Abhängigkeit von den Beschichtungs- und Vorreinigungsparametern untersucht.Insbesondere der durch das sogenannte Sputtercleaning beeinflußte Oberflächenzustand der Substrate beeinflußt das Aufwachsverhalten der Schichten in starkem Maße. Darüber hinaus konnten die Auswirkungen von Beschichtungsdruck und Sputteratmosphäre auf die Schichtstruktur gezeigt werden.Am Beispiel eines Verschleißversuches werden die Abhängigkeiten zwischen Schichtstruktur und Schichtverhalten unter tribologischer Beanspruchung dargestellt.

Notes: The design and features of an on-line purge and cold-trap pre-concentration device for rapid analysis of volatile organic compounds in aqueous samples are discussed. Excessive water is removed from the purge gas by a condenser or a water permeable membrane in order to avoid blocking of the capillary cold-trap. Synthetic mixtures covering concentrations ranging from tenths to tens of ppb's and different chemical classes are used to study the effect of various process factors on the efficiency and selectivity of water removal as well as on the purging recovery. The importance of the concentration of the solutes, the flow rate in conjunction with the volume of the purge gas, and the temperature of the condenser, the cold-trap and the sample is emphasized. Theoretical models describing the purge process and the blocking of the cold-trap agree fairly well with the highly reproducible experimental results (σ = 2-4%). Both the condenser and the Nafion membrane successfully remove water, although some compounds, dependent on volatility and polarity, are partly or completely lost. It is shown that non-polar volatile organic compounds are efficiently enriched so that recoveries between 80-100% and a detection limit of 1 ppt can be obtained. The applicability of the system is illustrated on some examples.

Notes: Trace enrichment for the GC analysis of a series of chlorinated pesticides and polychlorinated biphenyls (PCBs) in aqueous samples has been achieved through a simple on-line technique involving sorption on an LC micro-precolumn followed by direct elution into a gas chromatograph with hexane. A 5-m retention gap coupled to the capillary GC column served as the recipient of a relatively large sample volume (ca. 100 μl) introduced into the GC. Partially concurrent solvent evaporation during sample introduction allowed a large sample capacity. Recoveries of more than 95% were observed for the majority of the compounds studied. Using 1.0 ml aqueous samples, detection limits of less than 1 ppt were found. The applicability of the developed method was demonstrated for a river water sample.