Abstract: Plastic injection molding was simulated using software Moldflow. Mold temperature, melt temperature, packing time, packing pressure, cooling time, injection time, and V/P switch were taken as the affecting factors on the warp of injection molding parts. In one-factor-at-a-time experiments, the order of influencing weight was: packing tine>cooling tine>melt temperature>injection time>V/P switch>packing pressure>mold temperature. The first four were further studied using Taguchi method in an L9（34）orthogonal experiment. The effect of the factors was measured by signal-to-noise ratios (S/N) for warp, volumetric shrinkage, and sink index. The result indicated that melt temperature was the most important factors for warp.

Key words: Effect, Warp, Factor, Taguchi, Moldflow