Technical Informations

Causes of burns of plastic injection molded products and their solutions

Burns of plastic injection molded products are usually caused by different reasons such as machinery, molds or molding conditions.

The solutions for burns of plastic injection molded products are:

1.Mechanical reasons for plastic injection molding products

The barrel is overheated due to abnormal conditions, and the resin is injected into the product after high temperature decomposition and burns, or the resin stagnation caused by the nozzle and screw threads in the material cartridge, the check valve and other parts, which will be brought into the product after decomposition and discoloration. There are dark brown burn marks in the product. At this time, the nozzle, screw and barrel should be cleaned.

2. Reasons for the molds of plastic injection molding products

Mainly due to poor exhaust. This kind of burn usually occurs in a fixed place, which is easy to distinguish from the first situation. At this time, attention should be paid to measures such as adding a venting groove and an anti-venting rod.

3.Reasons for the molding conditions of plastic injection molded products

When the back pressure is above 300MPa, the barrel will overheat and cause burns. When the screw speed is too high, it will also produce overheating, generally within the range of 40 ~ 90r/min. When there is no exhaust groove or the exhaust groove is small, the injection speed is too high and it will cause burns from the overheated gas.

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