Plastic mold injection molding deformation, bending and twisting phenomenon is mainly due to the occurrence of plastic flow direction shrinkage is larger than the vertical, parts of anisotropic shrinkage is different, because the warpage of injection molding is inevitable in the part of residual internal stress caused by large warpage, here are the reasons about plastic injection molding the warpage and distortion and solutions.
1. Inadequate or uneven cooling
The top thrust of the mandril tends to deform the part when it is not fully cooled, so it will deform if it is not cooled sufficiently. The solution is to fully cool in the mold cavity, and then to be fully hardened before it can be pushed out. It can also reduce mold temperature and prolong cooling time.
2, caused by the forming strain
The deformation caused by the forming strain is mainly caused by the difference of the forming shrinkage in the direction and the change of the wall thickness. Therefore, the difference of the shrinkage in the direction can be reduced by increasing the mold temperature, increasing the melting temperature, reducing the injection pressure, and improving the flow condition of the gating system.
3, the rod caused
Some parts of the bad demoulding, the use of ejector rod forced demoulding caused deformation. The plastic parts which are not easy to deform are not deformed at the same time, but produce cracks. The elimination method is to improve the mold polishing, make it easy to release, and sometimes using the release agent can also improve the mold release.
4. Correction of warpage of products
If the product removed from the mold needs to be corrected, the simple method is to put the product to be corrected on the corrective tool and add weight to the warping place, but the weight of the heavy object must be clearly determined. Or put the warped product on the straightener, and put it into the hot water near the hot deformation temperature of the product, and simply straighten it with the hand. But pay attention to the temperature of hot water can not be too high, otherwise it will make the deformation of products more harm.