Abstract: In order to study the sequential injection molding technique for injectionmolded auto front bumpers, Moldflow software combined with pneumatic sequence valve technology was used to simulate the injection and cooling systems, and the positions of cavitation and weld line were forecasted. The sequential injection molding through 10 pin-point gates was simulated by Moldflow software. It was found that a mould locking force of more than 1820 tons and a reynolds number of 1000 were required in this injection molding technique. The auto front bumpers were produced on the basis of the above simulation optimizations. The results indicated that the sequentially injection molded auto front bumpers exhibited a good injection balance, good appearance quality and high production efficiency.

Key words: front bumper, sequential injection molding, moldflow analysis, optimization