Design Guides

Engineering best practices for defect-free, cost-effective cast iron components.

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Key Design Principles for Castings

Design Principles Infographic

1. Uniform Wall Thickness

Avoid abrupt thickness changes to prevent shrinkage porosity and warpage. Recommended range for iron castings: 6–12 mm. Gradual transitions only where necessary.

2. Draft Angle

Required to remove the casting from the mold without damage. Recommended: 1°–2° per side (larger for deeper cavities). Increases tool life and surface quality.

3. Fillets & Radii

Eliminate sharp internal corners to reduce stress concentration and crack risk. Rule of thumb: fillet radius ≈ nominal wall thickness. External radii also improve flow.

4. Avoid Sharp Corners

Sharp corners cause hot spots, shrinkage defects, and premature mold erosion. Always use radii or chamfers.

Bad vs. Good Design

Small changes in geometry dramatically affect castability and final quality.

❌ Poor Design

  • Abrupt wall thickness change → shrinkage cavity
  • Sharp internal corner → crack initiation
  • No draft angle → sticking, surface tear

✅ Optimized Design

  • Gradual thickness transition → sound structure
  • Generous fillet radius → stress distribution
  • Proper draft → smooth ejection
Bad vs Good Design Comparison

Design Considerations

Design Features Diagram

Parting Line

Position to minimize core complexity and flash. Avoid critical functional surfaces.

Shrinkage Allowance

Pattern must be oversized (approx. 1-2% for gray iron, 0.8-1.5% for ductile iron).

Ribs & Bosses

Add stiffness without increasing wall thickness. Keep rib thickness ≤ 0.8 x main wall.

Holes & Cavities

Cored holes reduce weight and machining. Minimum hole diameter: 12 mm for green sand.

Engineering Team Collaboration

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