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

Abstract

Injection 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.

Optimize Injection-Molding Process Parameters and Build an Adaptive Process Control System Based on Nozzle Pressure Profile and Clamping Force

“…It was found that when the clamping force difference value is zero, the mold will not separate [ 9 ]. Therefore, the clamping force difference was also monitored to prevent the mold separation.…”

“…The method effectively improves the stability of the product weight. Xu [ 9 ] et al mentioned that the product weight is stable when the clamping force shows no peak variation. Huang et al [ 10 ] mentioned that injection speed, V/P switchover point, and first-stage packing pressure settings are highly correlated with the cavity pressure profile and product quality.…”

Self‐optimization of the V/P switchover and packing pressure for online viscosity compensation during injection molding

“…Maximum injection volume 133 cm 3 Screw diameter Ø32 mm listed in Table 3. All of the polypropylene used in the experiments have the same density.…”

“…Injection molding machines (IMMs) are common equipment to form polymer materials. [1][2][3] More than 30% of plastic parts are molded by the IM process. [4,5] The repeatability accuracy of the part weight is a comprehensive evaluation standard reflecting the performance of an IMM.…”

Multiple In-Mold Sensors for Quality and Process Control in Injection Molding

“…The proposed methodology accurately determines an optimal clamping force using just six shots. Yang et al [ 38 ] proposed an experimental method to determine the optimal clamping force by measuring the difference between the clamping force before mold filling and after cooling. The optimal clamping force, according to the authors, corresponds to the moment when the clamping force change becomes zero.…”