Injection molds often produce burns during production for a number of reasons. The solution to burns due to different causes such as machinery, molds or molding conditions is different.
1. For mechanical reasons, for example, due to overheating of the barrel caused by abnormal conditions, the resin is decomposed at high temperature, injected into the product after burn, or due to the screw threads of the nozzle and the screw in the material, the stagnant flow of the resin caused by the check valve, etc. After being brought into the product, a dark brown burn mark is present in the product. At this time, the nozzle, screw, and cartridge should be cleaned.
2. The cause of the mold is mainly due to poor exhaust gas. This kind of burn usually occurs in a fixed place and is easy to distinguish from the first case. At this time, attention should be paid to measures such as adding an exhaust slot and an anti-exhaust rod.
3. In terms of molding conditions, when the back pressure is more than 300MPa, the cylinder part will overheat and cause burns. When the screw speed is too high, it will also produce overheating, generally in the range of 40~90r/min. When the slot or exhaust slot is small, excessive injection speed can cause overheated gas burns.