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
II. 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.