Warp Degree Optimization of Automobile Bumper in Sequential Injection Molding

Abstract

An automobile bumper is a large scale thin-wall plastic part. It is difficult for the weld lines of product to be removed by conventional injection method. Five valve gates in sequential injection have been used to control successfully weld lines to the border, but the warp degree of the product is too large. Through grey theory the packing pressure and time of valves opening and closing have been optimized. The grey relational degree have been calculated, the optimal process parameters group have been obtained by variance analysis. The result has been verified successfully in Moldflow software, the warp degree of product has been decreased greatly and satisfied the requirement of industry production. The injection method can be applied in actual production and increase corporate profits.