Things to keep in mind when making curb molds from plastic products include wall thickness and draft angle.
The wall thickness of plastic products must be determined by comprehensively considering the requirements of use and molding process. When used, the wall thickness should have sufficient strength and stiffness to withstand the shock and vibration of the demoulding mechanism during demoulding, and to withstand the tightening force during assembly. When molding, the wall thickness of the plastic product should be considered from a technical point of view, neither too thin nor too thick. If the wall thickness is too thin, the strength and rigidity are poor, and it cannot meet the requirements of use. In addition, it will increase the mold filling resistance, and even the mold will not be able to fill completely. However, the wall thickness should not be too large, otherwise too much material will be used, which will not only increase the cost, but also increase the molding time and cooling time, and reduce productivity. In addition, if the wall thickness is too large, it is prone to defects such as bubbles, shrinkage holes, dents, and warpage. In the case of thermoset plastics, it may also result in insufficient curing. It should also be noted that the wall thickness of the same product should be uniform to prevent internal stress in the product due to uneven solidification or cooling rates, which may lead to warping or even cracking of the product.
In order to facilitate the ejection of plastic products from the mold and scratch the surface of the product, there should be a reasonable demoulding slope parallel to the direction of the mold opening on the surface of the plastic product. The size of the slope depends on the shrinkage rate of the plastic, the shape of the plastic product, the wall thickness and its position, etc.
Generally speaking, the draft angle is 30°-45°. When plastic products have special requirements or high precision requirements, a small slope should be selected. For plastic parts with a large scale along the direction of mold opening, a small slope should also be used. Plastic products have complex shapes.