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Two reasons for the deformation of two-color plastic mold products

update:29-09-2019
abstract:

Two reasons for the deformation of two-color plastic mo […]

Two reasons for the deformation of two-color plastic mold products

1. The shape of the product, especially the residual stress caused by the relationship between the forming shrinkage and the thickness of the product.

2. Residual stress due to molding conditions;

3. Residual stress generated during demolding

4, due to lack of cooling time caused by deformation.

The science associated with the deformation of two-color plastic mold products:

1. The deformation (warping, bending, small wrinkles) of the product is the same as the cause of the crack. That is, the residual internal stress in the product. The setting conditions for molding should be set in the direction of stress in the product. That is, after the temperature of the barrel and the temperature of the mold are improved, the injection pressure is not too high in the state where the material activity is good.

2. In order to reduce the residual internal stress, there is a stop annealing treatment, that is, at a heat distortion temperature of 10 degrees or less, the heating of 2 hours or more has the effect of eliminating internal stress. However, annealing in this manner is not common due to the high cost.

3. It is assumed that the cooling water hole of the two-color plastic mold cannot uniformly cool the product, and residual stress is also generated, which means that the cooling water hole cannot be too shallow.

Plastic product deformation disposal method:

1. Immediately: fully cool and solidify in the mold (extend the cooling time chronograph), improve the barrel temperature and reduce the injection pressure.

2. Short-term: Make the mold cooling even.

3, long-term: to prevent the difference in thickness of the product, set the gate in the center of the product thickness, because the straight line is easy to cause warpage, make a large R curve, the product can reversibly bend the mold, increase the number of ejector rods, increase the demoulding Slope.