A, what is cracking steam white?

Cracking steam white: cracking is a more common defect of plastic products, including filamentary cracks on the surface of the parts, micro-cracks, top white, cracking and damage caused by the adhesive mold of the parts and the flow channel. According to the cracking time, it is divided into release cracking and application cracking. The main reason for

is due to stress deformation (mainly residual stress, external stress and stress deformation generated by the external environment). As shown in the figure

Two, how to improve?

1. Material:

appropriate use of release agents, pay attention to often eliminate the mold surface attached to the aerosol and other substances;

fully dry the material before molding processing;

Pay attention to the selection of paint and thinner that will not crack.

2. Molding process:

Avoid plasticizing stage of poor feed into the air;

improve the melt temperature and mold temperature, ensure the melt flow on the basis of the injection molding pressure should be reduced as far as possible;

Reduce screw speed, injection speed, slow down the initial speed of melt through the gate, the use of multi-stage injection molding;

Adjust the mold opening speed and pressure to avoid demoulding cracking caused by fast strong drawing products;

To avoid cracking due to weld marks, plastic degradation caused by strength everywhere;

Reduce the occurrence of cracks by eliminating the internal stress through annealing treatment immediately after forming.

If the surface of the plastic parts has been cracked, you can consider taking the annealing method to eliminate. Annealing treatment is lower than the thermal deformation temperature of plastic parts about 5 бу C temperature, fully heating plastic parts for about 1 hour, and then slowly cool it, it is best to produce crack plastic parts immediately after forming annealing treatment, which is conducive to eliminating crack. However, the residual stress is left in the crack, and the solvent in the paint is easy to make the crack develop into a crack.

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