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Author: MULAN –Plastic Molding Manufacturer
Cosmetic packaging molds generally use PMMA as the plastic raw material. Because it is an appearance product, the precision and transparency of the product surface are relatively high. Therefore, in the process of injection molding production, the requirements for molds and injection molding processes are also particularly high. However, in the actual injection molding production of cosmetic packaging molds, it is very easy to have melt lines on the surface of the product that are not clear enough, and vacuum bubbles are easy to occur inside, even if the method of freezing the surface with cold water cannot get good results. So how do we solve it.
1) Cosmetic packaging mold processing precision Transparent PMMA injection molding products have high requirements for injection molds. Generally, the materials and mold finishing requirements for cosmetic packaging molds are relatively high. If conditions permit, try to use Jingdiao and The high-speed milling process will effectively improve the surface accuracy of the product. 2) Increase the injection speed and reduce the injection pressure. For this type of transparent PMMA injection molding products, if you want to improve the surface accuracy of the product, if other conditions cannot be changed, you should use the multi-stage injection method. At the first nozzle, Concentrate the cold material as much as possible. For this kind of product that requires particularly high surface precision, the cold material has a great influence on the transparency. In the second stage of injection, the injection speed should be increased as much as possible, and the injection pressure should be reduced, which can effectively reduce the internal stress of the melt and improve the surface accuracy.
3) The vacuum bubbles of the PMMA material in the pressure holding stage are all caused by the fact that the internal pressure is not solid and the surface shrinks too fast, which leads to the concentration of the material on both sides. When the fluid is not closed in the internal channel of the cosmetic packaging mold, adding pressure at the end of the injection will reduce the vacuum bubbles caused by uneven filling of the product. Of course, this process will increase the quality of the product and increase the cost. .