Plastic ball stress is the main reason is that the molding process, the cooling rate is too fast, the plastic ball surface cooling first, the plastic ball inside the plastic or hot, but the ball outside the skin has been cooling molding, can not be synchronized with the inside of the compound Contraction, will cause very small cracks, of course, such a small cracks, it is difficult to detect, to solve the plastic ball stress methods are the following:

1. Plastic ball mold as far as possible without ice machine, because the plastic mold with ice water machine only about 10 degrees, plastic injection molding, the surface instantly cooling, and inside the plastic or hot, continue to shrink, resulting in stress cracking.

2. Plastic ball in the mold after the completion of molding, the top of the mold can not be cooled too fast, it is best to put all the containers, so that the plastic ball will remain very hot state, and then slowly cooling, so plastic ball stress Also reduced a lot, basically there will be no small stress marks appear.

3. For more than 20mm diameter of the special material, the above two methods can not completely solve the problem of plastic ball stress cracking, it is necessary to re-heating the plastic ball at about 100 degrees, because the heating process and re-cooling The process is to stress the process, so that the plastic ball will not deal with the problem of stress cracking.