The whitening of the Plastic Injection Mold is because the part of the injection molded part is exposed to excessive external force, which greatly weakens the chemical resistance and mechanical properties of the part, and makes the surface of the injection molded part white.
1. Pushing the ejector pin on the weak part of the plastic part will cause the whitening phenomenon to be aggravated.
2. The surface of the cavity is not smooth enough, which increases the demolding resistance.
3. The contact area between the ejector pin and the molded part is small, and the local force is large.
4. The temperature difference between the melt and the mold is too large, which increases the residual stress in the plastic part, and it is easy to appear white when subjected to local forces.
5. The cooling time is too short, and the stress in the plastic part is difficult to fully balance. When the local force is too large, it will cause whitening
6. The injection pressure is too large, and the residual stress in the plastic part is also large, resulting in whitening.
Solution:
1. The ejection device should be placed at the wall thickness of the molded part to reduce the ejection pressure.
2. Reduce the roughness of the cavity and reduce the demolding resistance.
3. Appropriately increase the cross-sectional area of the end of the push rod. Reduce the local pressure on the molded part.
4. The melt temperature should be lowered to reduce the temperature difference between the melt and the mold.
5. When the cooling time is too short, the cooling time should be extended appropriately.
6. When the injection pressure is too high, the pressure holding time should be shortened.
