An adaptive control methodology for the injection molding process. Part 1 : Material data generation

Process variations in the injection molding process can be attributed to a wide variety of possible causes, including process temperature variations. An adaptive process control system has been developed that is designed to compensate for melt temperature variations that can occur from cycle to cycle. Using this strategy, changes in melt temperature are detected by monitoring changes in the injection mold filling speed or pressure that are associated with the melt temperature induced viscosity changes. The pressure compensation phase of the molding process is then modified to compensate for the melt temperature change in an effort to achieve dimensional consistency. A number of material parameters are required for this adaptive process control algorithm. These include both rheological behavior, and pressure-volume-temperature behavior of the material being molded. This paper describes the concepts associated with this adaptive process control strategy, and outlines the experimental procedures required for characterizing the required material properties. The results of the experimental process control study will be presented later as a continuation of this paper.