A novel strategy to determine the optimal clamping force based on the clamping force change during injection molding

Abstract

AbstractInjection molding machines are widely used to fabricate plastic products with complex geometries and structures. They consist of an injection unit and a clamping unit. To withstand the pressure of the mold cavity, the clamping unit needs a high clamping force to hold the mold halves. Unfortunately, the clamping force is among the overlooked parameters of the injection molding parameters. Setting the clamping force at max is needed in practice to avoid flash defects for most operators. However, excessive clamping force creates problems for the machine. This study proposes a verification method for determining optimal clamping force based on the clamping force change ΔCF. When ΔCF becomes zero, the current set value of the clamping force is appropriate. A positive and negative ΔCF corresponds to an excessive and insufficient set value of the clamping force, respectively. Verification experiments are implemented on an electric injection molding machine with polypropylene (PP). The experimental results show that the novel strategy can basically calculate and identify the optimal clamping force with iteration method. The optimal clamping force value for current working conditions (620kN) is acquired after several automatic molding trials, which provides a direction for further research.