How should the surface or internal cracks of the plastic parts be overcome when injection molding is formed?
After the plastics injection molding on the surface or internal causes obvious cracks, this is mainly due to the material temperature, mold temperature is too low, slower injection speed, injection pressure is small, inappropriate position of inlet, insert the temperature is too low, plastic illiquid and mold venting is not good.Its adjustment and solution are:
1) improve the process conditions, namely, improve the temperature and mold temperature, speed up the injection speed and increase the injection pressure.
2) if the feeding port is not properly positioned, the quantity of feeding port is large or the process of the runner system is long, the resistance is too large or the material temperature drops too fast, and the surface cracks of the plastic parts are caused, and the feeding port and runner system should be adjusted.
3) change the mold cooling water channel so that it can be cooled evenly, eliminate or reduce the crack source caused by the excessive heat and cold change in the plastic parts.
4) if the plastic parts are too thin, too many embedded parts or uneven wall thickness, the plastic will appear at the junction of the thin thickness and the cracks will occur.At this time, we should improve the design of the plastic parts to make it better.
5) preheat the embedded parts before use.
6) before trying the mold, be sure to remove the water in the mold cavity, and use lubricant and mold release agent in proper amount.
7) if the mold exhaust is not good enough to produce cracks, it should be added in the mold with a vent tank and cooling tank, so as to fully eliminate the gas.
8) if the plastic fluidity is poor, and the distribution of fibrous filler is uneven, the liquid plastic should be replaced, and the packing should be improved to distribute evenly.