Abstract: A multiobjective optimization method was proposed through the combination of analytic hierarchy process (AHP) and grey relation analysis (GRA) applying to multiple quality indexes, such as warp, volume shrinkage ratio, and sink index. The normalized weighting value of three quality index was obtained by means of analytic hierarchy process. Injection molding process was simulated by using Moldflow and orthogonal experiment design，and the predicted value of each quality index was obtained. The grey relational coefficient of experiment sequence and each quality index was calculated, and then the grey relational grade was obtained by means of a comprehensive evaluation model which combined the analytic hierarchy process (AHP) with gray relational analysis (GRA) methods, the analysis of means was executed afterwards. Holding pressure of second stage was best significantly effective on the comprehensive quality index, followed by injection time. The optimal process parameters combination of the injection molding was injection time(1.2 s), holding pressure of first stage(120 MPa), holding pressure of second stage(120 MPa), holding pressure of third stage(80 MPa). The feasibility of the proposed method was demonstrated by the project of mobile phone shell.

Key words: injection molding, analytic hierarchy process, gray relational analysis