Abstract: Taking the volume shrinkage as an evaluation index for an air filter cover, a series of injection molding process parameters including melt temperature, mold temperature, flow rate, packing time and packing pressure on assembly dimension were optimized by means of orthogonal experiment and response surface method (RSM). The results indicated that, on the basis of orthogonal experiment, the injection molding conditions were optimized for a melt temperature of 210 ℃, a mold temperature of 50 ℃, a flow rate of 80 cm3/s, packing time of 12 s and packing pressure of 100 MPa, which resulted in a volume shrinkage of 5.988 %. On the other hand, the process conditions optimized by RSM were determined as a melt temperature of 214.91 ℃, a mold temperature of 59.46 ℃, a flow rate of 80 cm3/s, packing time of 12 s and packing pressure of 109.94 MPa, which resulted in a volume shrinkage of 5.520 %. The results also demonstrated that the volume shrinkage rate derived from RSM was lower than that from orthogonal design, indicating that the processing conditions optimized by RSM is more suitable for the injectionmolded parts with much higher precision.

Key words: orthogonal design, response surface methodology, air filter cover, injection mold, process optimization