Abstract: Numerous weld lines were formed in the course of dashboard manufacturing by traditional injection molding, which seriously influenced the appearance and mechanical properties of dashboard. In order to solve the problem, sequence control injection molding technology of hot runner was proposed, and its processing principle was introduced, optimized runner system of mould was designed on the basis of its processing principle. Through MOLDFLOW simulating analysis, formative causes of each weld line and air trap were studied, and each gate-opening time was optimized. The study found that by optimizing gate—opening time, filling sequence and flow route of melt could be effectively controlled, and thus reduced or even eliminated weld lines and air traps. Sequence control technology was of great practice significance in dashboard manufacturing.

Key words: weld lines, sequence control, dashboard, Moldflow, injection molding