The causes of deformation
1, the shape of products, especially
forming shrinkage relationship with product thickness caused by residual stress
2, due to the forming conditions
of residual stress in 3, parting the residual stress produced in 4, and
deformation due to insufficient cooling time
2. The associated knowledge
1, the deformation of the
products (warping, bending, small wrinkles) as well as the reasons of the
crack.The residual internal stress in the products.Molding set conditions
should be set in eliminate products of internal stress direction. Namely
improve material barrel temperature and mould temperature, the material liquid
get better state, the injection pressure is not too high.
2, in order to reduce the
residual stress, annealing processing, namely under thermal deformation
temperature of 10 degrees, more than 2 hours of heating has the effect of
stress relief. But this way because of the high cost of annealing and use is
not common.
3, if the mould cooling hole not
to cooling homogeneity of products, also can produce residual stress, which
means that the cooling hole can't be too shallow.
Third, solution.
1, instant: sufficient cooling
solidification in the mould (chronograph longer cooling time), and improve the
temperature of the material, reduce the injection pressure.
2, short-term: make mold cooling
uniformity.
3, long-term: avoid the
thickness of products, where product thickness large set gate (1-1), caused by
a straight line easy to warp, make it big R curve, products reversible bending
die, increase the number of ejection rod, increase the draft.
Four, differences in material:
1, the crystalline materials
(poly (PVC), polypropylene, pom, nylon),molding shrinkage rate, and easy to
cause bias, non-crystalline material (polystyrene (PVC, ABS) easy to cause
residual stress.
Five, the reference items:
1, use orthotics keep at room
temperature after molding, to prevent deformation, slightly but not hope too
much.
2, in the box forming of thin
shape, bending caused by molding temperature, this is common thermal expansion
more information www.cnmoulding.com www.plastic-injectionmoulding.com
没有评论:
发表评论