Plastic parts burnt mark
Burns caused by different causes, such as machinery, molds or molding conditions, may be treated differently.
1) mechanical reasons. For example, abnormal conditions caused the material cylinder to overheat, which caused the resin to decompose at high temperature and inject the product after burns
In, or as a result of the nozzle and screw thread, check valve and other parts of the material Jane caused by resin stagnation, decomposition and color change into the products, in the products with black brown burn scars.At this point, the nozzle, screw and barrel should be cleaned.
2) the reason of mold is mainly caused by bad exhaust.This kind of burn usually occurs in a fixed place, easy with the first
One case is different.At this time, attention should be taken to add the exhaust groove back exhaust rod and other measures.
3) in terms of molding conditions, when the back pressure is above 300MPa, part of the feeding tube will overheat and cause burns.The screw rotation speed
If it is too high, it will also overheat, generally within the range of 40-90r/min.When there is no vent or vent, excessive injection speed can cause superheated gas burns.