One. Deformation causes:
1, the shape of the article, particularly
molding shrinkage rates with the relationship between the residual stress
caused by the thickness of the article.
2, since the residual stress generated by
molding conditions
3, the residual stress generated when
stripping
4, due to insufficient cooling time caused
by the deformation
Two. The associated knowledge
1. Reasons product deformation (warping,
bending, small wrinkles) with the same cracks. I.e., residual stress within the
article. Molding conditions should be set towards the elimination of internal
stress setting products. That increase after the cylinder temperature, mold
temperature, the flowability of the material in good condition, the injection
pressure is not too high.
2, in order to reduce residual stress,
there is annealed, i.e., below the thermal deformation temperature of 10
degrees, there was heated over 2 hours to eliminate the effect of internal
stress. Annealing in this manner but the high cost due to the use of less
common.
3, if the cooling water hole of the mold
can not be uniform cooling products, will produce residual stress, which means
that the cooling water hole not too light.
Third, the solution.
1, real-time: in the mold sufficiently
cooled and solidified (prolonged cooling time timer) enhance barrel
temperature, lower injection pressure.
2. Short-term: the mold cooling uniform.
3. Long-term: to avoid differences in
thickness of the article to set the thickness of the gate in products where
large (1-1), because the straight line is easy to cause warping, made a large R
curve, reversible bending mold products, increase the ejection lever months the
number increased stripping slope.
Fourth, the material differences:
1, crystalline materials (polyethylene,
polypropylene, POM, nylon) Molding shrinkage, and prone to bias,
non-crystalline materials (polystyrene, ABS) likely to cause residual stresses.
more information www.plastic-injectionmoulding.com www.injectionmoldchina.com
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