Injection molds often appear black spots possible factors
Injection mold is also one of the common types of molds, in the manufacturing process, we often find black spots, or cause color injection when the color coking, which are common problems in the manufacture of injection molds, the main cause of this problem is plastic or The addition of ultraviolet absorbers, antistatic agents and other barrel overheating decomposition, or the barrel to stay too long, so that decomposition, coking, with the melt into the cavity formation. In order to avoid the emergence of these problems, we can from the following four aspects of analysis:
1, the machine side:
(1) due to heating control system out of control, resulting in barrel overheating caused by decomposition black.
(2) due to the screw or barrel defects to melt and hoarding, to withstand a long time fixed heating caused decomposition. Should check whether the plastic head wear or whether there is a metal foreign body.
(3) some plastics such as ABS in the barrel by the high heat and cross-linked coking, in almost the original shape of the particle to maintain the case, Injection mold it is difficult to melt, broken by the screw after the entrainment into the workpiece.
2, mold aspects:
(1) mold exhaust is not smooth, easy to burn, Injection mold or the size of the casting system is too small, too much shear caused by coking.
(2) mold has inappropriate oil lubricant, release agent.
Excessive plastic volatile, humidity is too large, too much impurities, renewable raw materials too much, contaminated.
(1) the pressure is too large, the speed is too high, back pressure is too large, the speed will make the material temperature decomposition.
(2) should regularly clean the barrel, Injection mold remove the plastic than the poor resistance of additives.