Defect Guide

Short Shot

Incomplete filling — the product is not fully formed. End sections or thin walls remain unfilled.

Common Causes

  • Insufficient injection pressure/speed
  • Melt temperature too low (high viscosity)
  • Undersized gate or runner
  • Poor venting (trapped air)
  • Insufficient shot size (metering)

Solutions

  • Increase injection pressure and 1st-stage speed
  • Raise nozzle/barrel temperature
  • Enlarge gate or improve runner
  • Add or clean vents
  • Increase metering stroke

Resin-Specific Notes

PA

Semi-crystalline: sharp viscosity change with temperature. Temperature control is critical.

PBT

Fast crystallization. Ensure adequate gate size.

PC

High viscosity. Requires high temperatures (280–320°C).

ABS

Relatively easy to process, but temperature management required.

LCP

Extremely low viscosity. Short shot is rare.

Resins Prone to This Defect

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This content is a field-reference summary. Final judgment requires on-site engineer verification.