Atlas of Casting Defects
Negative
Internal irregular cavity exhibiting an open or porous coarsely crystalline or dendritic structure usually exposed upon removal of the gate. This defect is frequently discovered by caustic salt bleed out from the cavity
N/A
Center of gates
N/A
Visual inspection, Penetrant Inspection
The molten alloy shrinks as it solidifies. Inadequate feed metal from the gating system is available to prevent a cavity from forming.a
| Area | Possible Cause | Potential Correction |
|---|---|---|
| Other (Gating design) | Gates are too small or too long |
Increase height of mold to increase ferrostatic pressure or the gate modulus, consider tapering the gate |
| Other (Casting design) | Low metal pressure |
Insulate, hot top or use exothermic material to prevent the pour cup from freezing too early |
| Foundry | Runner system freezing too early |
Use selective insulation to promote progressive solidification |
| Foundry | Gates are too small or too long |
Increase height of mold to increase ferrostatic pressure or the gate modulus, consider tapering the gate |