Influence of Injection Mold Temperature on Plastic Injection Parts and Causes of Mold Deformation

Influence of Injection Mold Temperature on Plastic Injection Parts

Table of content

Ⅰ. What effect does the temperature of the injection mold have on the plastic injection parts?

1. The influence of mold temperature on the appearance of plastic injection parts

If the mold temperature of the injection mold is too low, it will affect the crystallinity of the plastic and reduce the melt fluidity, which may cause the defect of under-injection, but the temperature of the injection mold should not be too high, and it is easy to stick to the mold if it is too high. of bright spots. If the temperature of the injection mold is too low, it will also cause the problem that the plastic injection parts are not easy to be demolded. When demoulding, it is easy to strain the plastic products, especially the plastic parts with patterns on the surface.

2. Influence on the size of plastic injection parts

If the mold temperature of the injection mold is too high, the plastic melt will be thermally decomposed, the shrinkage rate of the plastic product will increase, and the product size will become smaller. On the contrary, if the temperature of the injection mold is high, it will lead to a long cooling time of the molten plastic, slow relaxation, low orientation level, and at the same time, it is conducive to crystallization, and the actual shrinkage rate of the product will be larger.

3. The influence of mold temperature on the deformation of plastic injection parts

If the cooling system of the injection mold is unreasonably designed or the temperature is not properly controlled during the production of the injection mold, and the plastic product is sufficiently cooled, it will cause the plastic part to warp and deform. If the temperature difference of the injection mold is too large, the cooling of the plastic parts will be uneven, and the plastic shrinkage will be inconsistent, which will cause stress to cause the warping deformation of the injection molding parts.

4. The influence of mold temperature on internal stress

The mold temperature of the injection mold is low, the weld line of the plastic part is obvious, and the strength of the product is reduced; for the crystalline plastic, the higher the crystallinity, the greater the stress cracking tendency of the plastic part.

 

Ⅱ. What are the reasons for the deformation of the injection mold?

Deformation of injection mold means that the injection mold experiences excessive elastic deformation or plastic deformation during the working process, which makes the injection mold unable to work normally or the product quality declines unqualified.

1. Insufficient rigidity

During the injection molding process, the injection mold is subjected to a large injection pressure. The injection pressure will cause the injection mold to deform, but within the elastic limit of the steel material, the deformation of the injection mold can also be recovered. When deformed, the condensate will make the opening of the deformed mold difficult or even impossible to open.

When this happens, it is not possible to modify the mold structurally, but the injection pressure can be appropriately reduced, or the rigidity can be increased structurally from the outside.

2. Injection mold assembly problems

If the injection mold has a misalignment problem during the assembly process, and the injection mold clamping and joints are not accurately aligned, the unbalanced filling of the molten plastic will easily lead to deformation or misalignment of the injection mold.

In response to this problem, the injection mold should be disassembled and reassembled, and gate correction should be performed for unbalanced filling.

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