The design of exhaust system is very important because of the large size of automobile injection mold. If the design of exhaust structure is unreasonable, the quality of plastic parts will be seriously affected, including injection defects such as filling dissatisfaction, air entrapment and unsmooth demoulding. In serious cases, scorch marks will appear on the parting surface of the product. The lamp housing of automobile headlamp is an internal functional part, so it is very important to design exhaust reasonably. According to the characteristics of plastic parts, the exhaust groove is set on the moving die. This kind of exhaust groove is easy to process and can be directly processed by CNC. The following points should be paid attention to when designing the mold exhaust system:

1) The exhaust should be preferentially set at the end of the material flow and the corner of the plastic part.

2) Close to the insert or the thinnest part of the wall, where weld lines are most likely to form.

3) It's best to set it on the parting surface, because the overflow on the parting surface is the easiest to remove.

The exhaust design of the die is on the parting surface of the moving die side, as shown in the figure.