Study Of Unsymmetrical Structure's Gas Assisted Injection Molding

Gas assisted injection molding (GAIM), developed quickly in recent years, is anew kind of polymer processing technology.It has many advantages such as lowerinjection pressure, less warpage, better surface quality and easily processing productwith different wall thickness etc. Compared with traditional injection molding, GAIMhas more process variables needed to be specified and controlled, and therefore hassome special demand in processing control, product and mould design. With thedevelopment of computer hardware and software, there will be more space for usingCAE teclmology in GAIM. For the purpose of using this technology effectively, onone hand, we should introduce some better probability statistics and optimizationmeans to make the artificial experience quantized based on plenty of applications andexperiments; on the other hand, we should pay attention to the applications of CAEsoftware for GAIM.In this article, the arrangement and size design of gas channel, mould design andGAIM processing parameters to product quality were summarized. According to thedesign demand for unsymmetrical structure, created several typical CAD models withdifferent product and gas channel dimensions for rotation angle and planar structure.Use MPI, the mature plastic processing software, to simulate the GAIM process ofthe above CAD models. Under the same processing conditions, the influence ofthickness and breadth of base plate to gas channel penetration length, finger effectand melting-joint imprint were studied. Found that the melt flow can be effectivelycontrolled, the gas penetration to thin wall can be evidently restrained and the lengthof melting-joint imprint can be decreased by changing the thickness of base plate. Sothe quality of the product was improved. According to the simulation results, extractthe corresponding GAIM process parameters from the qualified product.Make the radius of gas channel, length of gas channel, ratio of breadth oftwo-sided cardinal plates and ratio of thickness of two-sided cardinal plates asindependent variables. Also, make the short shot, delay time, gas pressure, gasinjection time as dependent variables. Do the multiple regression analysis of thedependent and independent variables respectively with Matlb, so the regressionequation of GAIM processing parameters for the rotation angle and planar structurewere obtained.Finally, by testing the significance of the regression equation of GAIMprocessing parameters, verified that there was conspicuous linear correlation betweenGAIM process parameters and product and gas channel structure parameters. For thedesign parameters of any rotation angle and planar structure, using the regressionequation of GAIM processing parameters to predict the GAIM process parametersand its confidence interval.