plastic mould and custom injection moulding tips

On plastic injection products, especially for raw materials such as ABS, PP and PC, you will often see shiny stress marks on the surface of products, such as injector pin stress marks, insert stress marks and stress marks of wall thickness difference . These apparent shiny, white markings are the result of internal stresses , which are nothing more than orientation and cooling shrinkage stresses. The irregular stress marks near the gate are caused by the typical orientation stress, and the difference of wall thickness is the result of orientation and contraction stress, those stress marks are made by ejector pins and sliders . Normally , with the increase of holding pressure and time, the first occurrence is the stress mark of wall thickness difference, the stress mark of ejector pin, then the stress mark of meat thickness difference, and finally the irregular stress mark near the gate (gray section will appear on the side), which of course also depends on the specific structure of the

If want to reduce or eliminate cracking of injection molded poly-carbonate, it can take two measures: Reduce internal stress; Or improve the cracking resistance of plastics. What can do to reduce the internal stress of the PC injection molding process ? Mold Temperature Increasing the mold temperature can reduce the internal stress. When the mold temperature is controlled between 80 ~ 110 degrees, the internal stress is small. Barrel Temperature Increasing the  barrel temperature can reduce the internal stress. For the PC part injection molding, the barrel temperature can be controlled between 260 ~ 330℃, and the higher the temperature is, the lower the internal stress will be. Ejection Pressure The viscosity of PC material is high, which  requires high pressure in theory, but high pressure will greatly increase internal stress, so it is inappropriate to use high pressure here. The pressure should be kept between 800 ~ 1200 kg. Ejection speed High ejection speed wi