Designing castings for sand mold production
| Allowance Type | Value (Cast Iron) | Purpose |
|---|---|---|
| Shrinkage | 1-2% | Compensates for metal contraction |
| Draft | 1-3 degrees | Pattern removal from sand |
| Machining | 2-5mm | Surface for final machining |
Gating ratio (sprue:runner:gate): 1:2:1 for steel, 1:4:2 for iron. Riser volume: 50-100% of casting volume for steel.