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How to Avoid Short Shot in Plastic Products?

1. Phenomenon

An incomplete phenomenon in which the resin is not completely filled. And this is called short shot.

2. Cause

  • Overly runner/gate diameter
  • Long runner
  • Large flow resistance in cavity
  • Poor degassing of sprue and runner
  • Insufficient air escape in the mold
  • Lack of supply
  • Insufficient injection pressure
  • Slow filling speed
  • Low resin temperature
  • Low mold temperature

short-shot

 
 

3. Measures

  • Increase runner/gate size
  • Review runner placement
  • Change the position of the gate
  • Provide sufficient gas venting to the sprue and runner
  • Vent the unfilled part
  • Degas just below the sprue part and at the runner end.
  • Increase the air vent near the final filling part of product.
  • Optimum material supply
  • Increase injection pressure, injection speed, cylinder temperature, mold temperature
  • It occurs when it is difficult to fill due to vent clogging.
  • By taking good venting measures with the mold, there is no air resistance in the mold and molding at low pressure is possible.