AN INJECTION-MOLDING STUDY .1. MELT AND BARREL TEMPERATURE DYNAMICS

The dynamics of the key variable in the plastication phase of injection molding were studied using a microcomputer controlled laboratory scale injection molding machine. Interfaces for the measurement and manipulation of suitable variables were developed. An approximate theoretical analysis provided a preliminary understanding of the effect of a step input in heating power on melt and barrel temperatures. Deterministic and stochastic models were derived from experimental data for the melt and the front and rear zone barrel temperatures with heater power manipulation. Experiments were performed for evaluating the effects of back pressure manipulation, heating zone interaction, and process disturbances on the melt and barrel temperatures. Experiments showed that it is desirable to directly control the melt temperature rather than the barrel temperatures.