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| Record 99：How to adjust the finish? |
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Key Word：Taili Plastic Machinery, Injection Molding Machine, Interests, Product Finish
It's very hot these days. The outdoor temperature in Ningbo has reached 40 degrees. I received a call from Master Li, saying that they have recently received a batch of new orders. The brand side has particularly high requirements for the surface finish of the products. He has adjusted it for more than 3 hours but still has been unable to solve the problem.
I saw the product in master Li's factory, which was the outer surface of the smart socket. The material was required to be nylon and glass fiber. The brand side has very high surface accuracy of the product and requires the product to be observed with no obvious surface defects with the naked eye.
In fact, for such products, many machine adjustment technicians have the following confusion: for products requiring high surface accuracy, should the injection speed be fast or slow?
For general injection molding technicians, if the surface accuracy of the product is required to be high, the injection speed of the product should be as slow as possible, and multi-stage injection should be carried out for places with different thickness.
In fact, according to my experience, this idea is wrong. If the viscosity of raw materials is not high, for most products, especially those added with glass fiber, when filling the mold cavity, the injection speed should be as fast as possible and the injection pressure should be as low as possible.
Only when the viscosity of raw materials is high, such as PVC, the injection speed should be as slow as possible to avoid melt breakage and yellowing.
Adjusting idea
For this product, during the mold test of the first several molds, the injection time and injection speed required for the fluid to the water inlet should be tested as much as possible. If conditions permit, the filling water inlet should be as slow as possible, and the cold material in the material storage should be concentrated at the water inlet as much as possible. Fill the mold cavity fast, which can improve the surface accuracy.
Pay attention to contraction
For the product requirements observed by the naked eye, in addition to the improvement of the injection molding process, pay attention to the shrinkage of the product. Generally, the injection temperature of this material is about 220 degrees. Due to the influence of the runner, the fluid temperature close to the nozzle is high, which is prone to suffer shrinkage deformation. The method of quick freezing the outer surface of the product with cold water can be used to improve the surface accuracy of the product.
Mr. Li adjusted according to my idea and there turns out to be no problem.
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