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Causes and solutions for deformation of injection molding products

Causes and solutions for deformation of injection molding products

Issue Time:2020-12-11

injection molding In the process of injection molding, there are often deformation and bending of products. What are the main causes of plastic deformation and how to solve them?

First of all， mould

The thickness of the plastic injection molding must be uniform, otherwise it may cause deformation， The design of the cooling system should make the temperature inside the mold uniform, and the injection system should make the material flow symmetrical to avoid warpage

 It is also necessary to thicken the flow channel if we processing of the difficult forming part

and try to eliminate the density difference, pressure difference and temperature difference in the mold cavity.

The mold should have good demoulding performance, such as increasing the Inclination, improving the surface polishing , and keeping the ejection system balanced.

in addition Increase the wall thickness of injection molded parts, increase the anti warping direction, or add stiffeners to enhance the parts anti warping ability These methods can also prevent product warpage


Second: raw materials: insufficient material strength will also cause product deformation

Crystalline plastics have a higher probability of warpage than non crystalline plastics. The crystallinity of crystalline plastic will decreases when the cooling rate increase, and the shrinkage rate decreases. We can use this feature to correct it.


Third, the production：

If the injection pressure is too high, the melting temperature is too low and the speed is too fast, the internal stress will increase and the warpage will appear.

If the temperature of plastic injection mould is too high and the cooling time is too short, the parts during demoulding will overheat and the product will deform， We can reduce the screw speed and density to limit the internal stress while keeping the minimum feeding speed.

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