The main reason for the whitening phenomenon is that the stress is whitish due to the external force acting on the surface of the product. It mainly occurs in the ejection position of ABS resin products. Poor demoulding is the main reason.

Causes:

In most cases, the whitening area is always located at the ejector of the part. In addition, if the mold temperature is too low and the flow channel is very narrow, it will cause the temperature of the melt front to drop quickly, and the curing layer will be thicker.

Solution:

After whitening, it can be improved by reducing the injection pressure, increasing the demoulding slope, increasing the number or area of the pusher, and reducing the surface roughness of the mold. In particular, chamfering should be prevented near the reinforcing ribs and bosses. The ejection device of the demoulding mechanism should be arranged at the wall thickness of the plastic part or appropriately increase the thickness of the ejection part of the plastic part. In addition, the finish of the cavity surface should be improved to reduce the demoulding stress. Of course, spraying release agent is also a method, but care should be taken not to adversely affect subsequent processes, such as hot stamping, painting, etc.