The hottest method to eliminate product deformatio
2022-09-22- Detail
Methods to eliminate product deformation
causes of deformation
1 the shape of the product, especially the relationship between the forming shrinkage and the thickness of the product, is also inseparable from the residual stress of the packaging of the mouth sealing machine
2 residual stress due to forming conditions
3 residual stress due to demoulding
4 deformation due to insufficient cooling time
related knowledge
1 the deformation (warpage, bending, small wrinkles) of products is the same as the cause of cracks. That is, the residual internal stress in the product. The setting conditions of molding should be set in the direction of eliminating the internal stress of the product. That is, after increasing the barrel temperature and mold temperature, the injection pressure should not be too high when the material fluidity becomes better
the original automatic control hydraulic material testing machine used an electro-hydraulic servo valve to form a control system. 2 in order to reduce the residual internal stress, annealing treatment was carried out, that is, heating for more than 2 hours under the thermal deformation temperature of 10 degrees can eliminate the internal stress. However, this method of annealing is not widely used because of its high cost
3 if the cooling water hole of the mold cannot evenly cool the product, residual stress will also be generated, which means that the cooling water hole cannot be too shallow
III. solutions
1 immediate: fully cool and solidify in the mold (extend the cooling time timer), increase the barrel temperature and reduce the injection pressure
2 short term: cooling the mold evenly
The clamping unit can adjust3 for a long time: to avoid the difference in the thickness of the product, set the gate (1) where the thickness of the product is large. Because the straight line is easy to cause warpage, it is made into a large R-curve. The mold of reversible bending of the product, increase the number of ejector rods, and increase the demoulding slope
I. differences in materials:
1 crystalline + 3 materials (polyethylene, polypropylene, POM, nylon) have large molding shrinkage and are easy to cause bias, while non crystalline materials (polyethylene, ABS) are easy to cause residual stress
II. Reference items:
1 after molding, keep it with orthotics at room temperature, which can slightly prevent deformation, but don't expect too much
2 in the forming of thin boxes, the bending caused by the forming temperature is common in thermal expansion alone
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