Injection Molding Analysis and Parameter Optimization on Precise Thin Shell Product

• Main Authors: Chou, Chia-Hung, 周家宏
• Other Authors: Cheng, Pi-Ying
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/72904330528586504778

碩士 === 國立交通大學 === 機械工程系所 === 97 === The invention of DVD was a great contribution to data storage. In order to improve DVD manufacturing efficiency and decrease the production cost, so the purpose of this research aims to analyze the effective factors of warpage of DVD and find optimal parameters in injection-molded process applying the Taguchi method. As to reduce injection-molded product cycle time will increse the warpage of products, especially for thin-wall injection parts, will reduce the quality, and decrease production efficiency. So we expect to find the optimal set of injection molding process parameters that can reach the goal of both reducing production cycle time and keeping the quality of products. This research used the experimental design of Taguchi method to determine the injection molding conditions, and the injection processes were simulated using the commercial software Moldex3D. The application of Taguchi optimization technique to reduce warpage problem related to the shrinkage variation with critical process parameters was studied. For this purpose, several cases about Moldex3D analysis are carried out by utilizing the combination of process parameters based on five-level of L25 Taguchi orthogonal array design. In most of the cases, six critical injection parameters were used.These parameters are injection time, melt temperature, mold temperature, packing time, packing pressure and cooling time.The signal-to-noise (S/N) are used to find the optimum levels and to indicate the impact of the process parameters on warpage. In addition, applying the experimental design of Taguchi method is a quite effective method to deduce the optimum set of effective factors in injection molding to produce plastic parts with minimum warpage. Based on the resolved data suggested by the current research, the product efficiency has been improved. DVD production cycle time can be reduced to 5 second, in the case that the warpage of discs were keet in the region of 0.063mm attain to production standard. The experimental results indicate that the quality of products are improved greatly while using another layout of the cooling chanels designed by our Lab(NCTU CIDM Lab). In this experiment, selecting suitable cooling chanels and keeping the other parameters the same can reduce the critical warpage value more than three times. Applying the concluded regulation from the study of the simple thin-shell plastic parts to the model of general 3D surface thin-shell parts, the results showed that the factor of packing pressure was aslo the critical factor to the warpage issue. In addition, this research proposed three different kind of material to the simulation tasks of complicated phone cover, the results showed that the quality of the tested phone cover are improved, that the warpage was reduced from 7% to 18% by using the proposed method of modified Taguchi optimization method.