Warpageanalysis And Research Of Mobile Phone Shell Injected Plastic Part With Thin-wall Metal-insert

The difference of the insert injection molding (i.e. the injection molding of the plastic part with insert in the paper) and the injection molding is that the insert must be assemble into the cavity before the molding in the insert injection molding. Warpage is the most serious molding defect of the insert injection molding. It's an important sdandard to measure the quality of plastic part. It affects not only the appearance of products but also the usability of products. Thus it is the important problem needed to research continuously to reduce warpage, optimize the structure of mold and molding process.Firstly, the reasons of the warpage for mobile phone shell with thin-wall metal-insert are analyzed in the paper including heterogeneous shrinkage, molecular orientation and heterogeneous cooling. The heterogeneous shrinkage is the important reason among them. The factors causing the warpage include injected material, the structure of product, the structure of mold and molding process.Then, the injection mold of the mobile phone shell with thin-wall metal-insert is optimized to carry on injection experiment. It is found that the warpage of mobile phone shell is very big and it's very difficulty to reduce the warpage by adjusting the molding process manually.Thirdly, on the basis of the CAE analysis, the Taguchi test was applied to research the effects of the molding process parameters on warpage. The research results show that the best molding process that the warpage is the least is melt temperature 310℃, mold temperature 120℃, injection time 0.3s, hold pressure 140MPa, packing time 5s and cool time 6s. The effects of the molding process parameters on warpage are in the following descending order: packing time (48.3817%), hold pressure (34.3789%), cool time (6.7094%), melt temperature (6.5166%), injection time (2.6359%) and mold temperature (1.382%). And the best molding process is used to experiment. It is found that the warpage is 45% smaller than the smallest one before. It is proved that the Taguchi test is applicability well on optimizing moldiong process and reducing warpage.Finally, the rationale of the BP neural network is used to fit the nolinear relation of process parameters such as melt temperature, mold temperature, injection time, hold pressure, packing time and cool time and warpage. The warpage forecast model of the mobile phone shell with thin-wall metal-insert is build. The result shows that the precision of the BP neural network is high. And the computation speed of the forecast model is quick. It is effective to optimize the wrapage of the mobile phone shell.