Trust in engineering is built by teaching, not claiming. These guides explain how we think about casting design, material choice and defect prevention — useful whether you buy from us or not.
Grey iron's flake graphite gives damping and easy machining but low ductility. Ductile iron's spheroidal graphite bends before it breaks. The rule of thumb: steady, compressive loads lean grey; impact, fatigue or safety-critical loads lean ductile. Section thickness and machining then narrow the exact grade.
Keep walls uniform (differential shrinkage cracks parts), add generous fillets (sharp junctions cause hot tears), give every vertical face draft (so the pattern releases), avoid isolated heavy sections (they need risers or they shrink), and mark machined surfaces (that drives the pattern size).
The gating system controls how metal enters — fast enough to avoid cold shuts, calm enough to avoid sand inclusion. Risers feed liquid metal into the casting as it shrinks during solidification. Undersized risers are the number-one cause of shrinkage porosity. Castings should solidify directionally, from thin toward thick toward the riser.
Shrinkage (fed by risers and chills), gas porosity (controlled by sand moisture and clean melt), inclusions (prevented by calm filling and hard moulds), and dimensional error (held by accurate tooling and mould hardness). Every stage in our process maps to stopping one of these.
| Defect | Common cause | Corrective action |
|---|---|---|
| Macro shrinkage | Riser too small / freezing early | Increase riser modulus; add sleeve; reposition |
| Gas porosity | Sand moisture / dissolved gas | Control sand moisture; degas melt; check cores |
| Cold shut / misrun | Metal too cold / slow fill | Raise pouring temp; increase in-gate area |
| Sand inclusion | Mould erosion / turbulent fill | Reduce gate velocity; harder mould; check binder |
| Hot tear | Restricted contraction | Improve mould collapsibility; check composition |
This is the same diagnostic logic we apply on our own floor — and when we consult for other foundries.
Whether it's a design you want reviewed or a defect you're chasing, our engineers are happy to talk it through.