Abstract: Using orthogonal experiments and Moldflow simulation, the process in the injection molding of lower plaques for Apillars of vehicles was simulated. The influences of different molding process parameters such as mold temperature, melt temperature, injection time, and packing pressure on the warp deformation and residual stress were studied. It was found that the melt temperature constituted the most influential factor to warp deformation, packing pressure was the most influential factor to the residual stress. A set of optimal process parameters was found to be mold temperature 40 ℃，melt temperature 205 ℃, injection time 5 s, the packing pressure 45 MPa. Compared with regular processing parameters, warp deformation decreased from 3.847 mm to 3.121 mm, residual stress decreased from 66.95 MPa to 65.21 MPa.

Key words: Moldflow, lower plaque for Apillar, injection molding, simulation, residual stress