The application of modified PVT data on the warpage prediction of injection molded part

The warpage of injection molded part strongly depends on the shrinkage property, which is highly dominant by the Pressure-Volume-Temperature (PVT) curves. Accurate description of PVT curves is essential for running the simulation of warpage. The standard PVT curves are measured at different pressure for the isotactic polypropylene, which are modified with the help of crystallizing curves obtained by the Differential Scanning Calorimetry (DSC) tests at different cooling rate. The user subroutine UEXPAN is coded to describe the modified PVT curves and implemented into the FEA model for warpage prediction in Abaqus. The simulated deflection of a plaque is performed and compared with the one measured by the coordinate measuring machine (CMM). It is concluded that the specific volume at high cooling rate varies slower with the temperature than that at low cooling rate and thus the predicted deflection with modified PVT data decreases significantly with increasing cooling rate. This numerical observation matches well with the experimental result. The warpage decreases when the crystallinity increases from 33 to 60 %. The plaque has the lowest peak deflection when the cooling rate is 60 °C/min. The system is built successfully for the warpage prediction of injection molded part.