Hot Tear

Hot TearHot tear presents as a jagged crack line through the casting. This defect indicates that the metal filled the mold, but cracked at solidification (the metal shrinks as it solidifies and tears apart due to restriction).
Note: some metals are more prone to hot tearing than others.

The causes of this defect are evident in the shell, metal and other portions of the process. To cure these causes, R&R recommends taking the following actions.

 

Area

Cause

Cure

Wax

 

 

Shell

  1. Shell is too strong.
  2. Shell is too hot.
  3. Poor crushability of ceramic mold (high post fired strength).
  1. Reduce shell strength, number of coats.
  2. Reduce shell temperature.
  3. Reduce post fired strength.

Metal

  1. Metal is too hot.
  1. Reduce/control metal temperature.

Other

  1. Improper gating.
  2. Movement of shell before metal solidifies.
  1. Modify to reduce cooling stress/shrinkage.
  2. Allow time for metal to solidify before movement.

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