How to Deal with the Warpage in Injection Molding?

About the warpage

1. Phenomenon of warpage

A phenomenon in which a molded product warps in a convex or a concave shape immediately after molding.

2. Causes of warpage

  • Unbalanced protrusion of molded products
  • Bad mold release
  • Uneven cooling
  • Big gate
  • Stick out quickly
  • High injection pressure, high injection speed
  • Short injection/holding time

3. Measures to avoid warpage

  • Prolong mold cooling time and balance mold temperature
  • Balance the overhang
  • Take a sufficient taper and apply a release agent
  • Make the gate smaller
  • Degas just under the sprue part and the runner end part.
  • Providing degassing processing on the protruding pin
  • Slow down stick-out speed
  • Lower injection pressure, slow down injection speed
  • Increase injection/holding time
  • Degas the runner end just below the sprue before entering the product. By increasing the number of vents, the air resistance to the product part is eliminated and the rise in internal pressure is suppressed.

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