Investigation of mold plate separation in thin‐wall injection molding

Abstract

Precision injection molding of thin-wall parts has become an important concern in 3C (computer, communication, and consumer electronics) plastics industry. Previous studies in precision injection molding control focused on the injection screw, the hydraulic system control and the associated operations. In the present study, the influence of relevant parameters, including injection speed, melt temperature, mold temperature, filling-packing switchover, and packing pressure, on the mold plate separation under different clamping pressures was investigated as part of precision molding control. A two-cavity tensile test specimen mold equipped with four linear variable displacement transducers (LVDTs) on mold exteriors and across the parting surface was used for experiments. A PC-based monitoring system was also built to detect the mold separation signals. Mold separation can also be identified from part weight variation and exhibits relevant correspondence with part weight. It was found that because of the high injection speed required for thin-wall molding, mold separation is not negligible. In all situations, mold separation decreases with increasing clamping pressure. As melt temperature and mold temperature increase, mold separation increases, resulting in an increase of part weight. Similarly, when packing pressure and injection speed increase, mold separation also increases. Earlier switchover from filling to packing can decrease mold separation as well as part weight. Among all parameters, packing pressure

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

“…Chen discovered that because the two mold halves are mutually compressive, for simplification, the movable mold half is selected for analysis, whereas the stationary half is considered a rigid body. [ 21 ] Figure 4A depicts the force state before clamping, and the location of the mold half is fixed. After mold clamping, the mold halves are compressed, which causes elastic deformation of the mold and the stretching of the tie bars.…”

Filling-to-Packing Switchover Mode Based on Cavity Pressure for Injection Molding

“…There are also a number of techniques have been developed to trigger the switchover. These include switchover by nozzle pressure [3], tie bar load or deflection [4], mold separation [5][6][7][8], ultrasonic [9] and capacitive transducer [10]. Of some debate in the injection molding industry is to which switchover mode provides the best shot to shot consistency.…”

Effect of machine compliance on mold deflection during injection and packing of thermoplastic parts

“…Chen et al [5] studied the influence of injection-molding process parameters, including injection speed, melt and mold temperature, filling/packing switchover, and packing pressure, on mold separation for thin-wall moldings under different clamping pressures. A finite element model of the mold using ANSYS with injection pressures from Mold-Flow was developed to predict mold separation.…”