Several reasons for the two-shot plastic mold deformation

Several reasons for the two-shot plastic mold deformation

Sometimes we will find that the two-color plastic mold products will be deformed. Do you know the reason why the two-color plastic mold products will be deformed? The following is for everyone. There are several reasons for the deformation of two-color plastic mold products.

  • 1. Residual stress due to molding conditions;
  • 2. Residual stress generated during demoulding;
  • 3. Deformation caused by lack of cooling time.
  • 4. The shape of the product, especially the residual stress caused by the relationship between the molding shrinkage and the thickness of the product.

Knowledge related to the deformation of two-color plastic mold products:

  • 1. The deformation (warpage, bending, small wrinkles) of the product is the same as the cause of the crack. That is, the residual internal stress in the product. The setting conditions for molding should be set in the direction of reducing the internal stress of the product. That is, after increasing the barrel temperature and the mold temperature, the injection pressure should not be too high when the material activity becomes better.
  • 2. In order to reduce the residual internal stress, annealing treatment is suspended, that is, the heat distortion temperature is below 10 degrees, and heating for more than 2 hours has the effect of eliminating internal stress. However, this method of annealing is not commonly used because of its high cost.
  • 3. It is assumed that the cooling water holes of the two-color plastic mold cannot stop the uniform cooling of the product, and will also generate residual stress, which means that the cooling water holes cannot be too shallow.

If this happens, there is no need to panic. Here we introduce the method of centralized disposal:

  • 1. Instant: Fully cool and solidify in the mold (extend the cooling time timer), increase the temperature of the barrel, and reduce the injection pressure.
  • 2. Short-term: make the mold cooling uniform.
  • 3. Long-term: To prevent the difference in product thickness, set a gate in the center of the product thickness. Because the straight line is easy to cause warpage, a large R curve is made. The mold of the product can be reversibly bent to increase the number of ejector rods and increase the draft angle.
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