Rheological techniques, like oscillating rheometry and high-pressure capillary rheometry were used to measure and to describe chemical and physical aging influences on the rheology of polyamide and polybutylene terephthalate in an advanced viscosity model. Viscosity drop was found as cause of combined time and temperature effects and understood as chemical aging that was reduced to a thermally induced degradation. The influence of chemical aging on viscosity was described based on a novel structural change shift factor a SC . In addition, viscosity drop was found as cause of residual moisture. Its influence was described by a novel physical change shift factor a PC . The functional relationships for both factors were derived from measured data. Moreover, both factors contain additional parameters that were optimized with respect to specific processing and boundary conditions. The consideration of chemical and physical aging by means of a SC and a PC provides a better understanding with respect to rheological changes and thus a better control of process variations and an enhanced product quality. POLYM. ENG. SCI., 55:1628-1633
Qualitätsregelung beim Spritzgießen (Teil 2): Adaptive, druckgeregelte ProzessführungAktuelle Produkte fordern höchste Präzision bei der Erfüllung von Qualitätskriterien und Schnittstellenanforderungen. Die Reproduzierung der Prozessparameter beim Spritzgießen reicht hier nicht mehr aus, um diese Anforderungen zu gewährleisten. Störungen der Prozesse sind vielfach auf Alterungs-und Konditionierungseinflüsse auf das Materialverhalten zurückzuführen. Ausgehend von einer detaillierten Materialcharakterisierung und erweiterten Beschreibung des rheologischen Verhaltens wird eine adaptive, druckgeregelte Prozessführung entwickelt. Die Auswirkungen auf den Prozess durch variierende Materialeigenschaften werden sowohl in der Simulation als auch realen Prozess dargestellt und mit der neuen Qualitätsregelung zur Kompensation von Störungen verglichen.
Quality control in injection molding (part 2): Adaptive, pressure controlled process managementActual products demand very accurate reproduction of the defined quality criteria and interfacial criteria for following processes. The reproduction of process parameters in injection molding is no more sufficed to guarantee the quality requirements. Process disturbances are often related to aging and handling influences on the material behavior. Therefore a material characterization leads to an extended model approach to describe the rheological behavior under aging influences and the development of an adaptive, pressure controlled process management. The process influences by varying material properties are shown in a process simulation, compared to the injection molding process and compensated by the new quality control strategy. archivierte, peer-rezensierte Internetzeitschrift archival, peer-reviewed online Journal of the Scientific Alliance
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