NUMERICAL ANALYSIS PREDICTION ON SHRINKAGE AND WARPAGE IN INJECTION MOLDING PROCESS

• Main Author: Harjanto, Syaiful
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/53628
• Institution: Institut Teknologi Bandung

Injection molding has become one of the most common methods in plastic manufacturing industries. Shrinkage and warpage significantly influence the dimension of the final injection molded product. A numerical analysis is preferably done before the injection molding process to investigate the potential defects. The simulation offers risk reduction due to mold manufacturing mistakes, cost minimization in the injection molding process, and easiness in virtually evaluating alternative material. Some numerical analyses have demonstrated to predict warpage using different measurement features and methods. Those may not accommodate when the user wants to measure the warpage applying camera-based measuring equipment. This research aimed to develop the numerical analysis modeling to simultaneously predict the perpendicular shrinkage, parallel shrinkage, and warpage of a rectangular thin-shell product by introducing the node measurement method. The full sequence from filling, packing, cooling to warp of Moldflow Plastic Insight analyzed the shrinkage and warpage. Design of experiment was conducted to investigate the effect of process parameters. The melt temperature and packing pressure by regression analysis significantly affect all the perpendicular shrinkage, parallel shrinkage, and the warpage. The simulated warpages show similar trends with higher values by node measurement than the real experiment. The Bland-Altman analysis showed the agreement between the simulation method and the experimental method with the bias were 0.196% on perpendicular shrinkage, 0.45% on parallel shrinkage, and 0.2 mm on warpage. An estimation method to reduce the error should be developed to get the best-fit prediction.