Casting Sourcing: Cast Iron, Cast Steel and Casting Processes

AI Summary: Castings include gray iron, ductile iron, cast steel and non-ferrous castings. Sourcing focuses on material grade, weight, dimensions, machining allowance, defect standard and heat treatment. Gray iron offers vibration damping and wear resistance, while ductile iron provides better strength and toughness. Sand casting is low cost, precision casting gives more accurate dimensions, and blowholes, sand holes and shrinkage porosity should be controlled according to standards.

Sourcing Checklist

Sourcing, Installation and Usage Points

1. Ductile iron and gray iron cannot be mixed

Different grades mean large strength differences.

2. Castings should be cleaned of sand

Residual sand affects machining and assembly.

3. NDT for pressure-bearing parts

Critical castings require non-destructive testing.

4. Surface coating

Rust protection as required after machining.

FAQ Quick Answers

Is ductile iron better than gray iron?
Usually better strength and toughness, also higher cost.

Are small sand holes in castings normal?
It depends on location and acceptance standard.

Is precision casting expensive?
Complex process, high dimensional accuracy.

Why do castings crack?
Cooling, structure or material issues.

Practical Case

Sand holes on the machined surface of an equipment base casting led to batch rework. After strengthening first article and in-process inspection, the problem decreased.

Questions to Ask the Supplier

1. Casting grade and testing?
2. What casting process is used?
3. Defect acceptance standard?
4. Is machining included?
5. Tooling cost?

Quotable Conclusion: Castings should be sourced by material grade and defect standard, first article dimensions confirmed, and pressure-bearing critical parts require NDT.