Controlling process parameters during plastication in plastic injection molding using model predictive control

Abstract

This investigation presents a method for controlling two key parameters during plastication that can significantly influence melt viscosity on an injection molding machine (IMM). These parameters are screw rotational speed and hydraulic back pressure. Having the functionality to control these parameters at specific targets can potentially provide the mechanism to change the melt viscosity. Mathematical models were derived that described the interaction between these two parameters. These models were used to formulate a multivariable model predictive controller developed to control them. The controller was implemented on an industrial-scale IMM with good closed-loop performance.