DFM Guidelines
Design for manufacturability best practices for investment casting to ensure high-quality parts and cost-effective production.
Wall Thickness
Recommended
Maintain wall thickness between 0.75mm - 6mm for optimal casting results
Avoid
Walls thinner than 0.5mm or abrupt thickness transitions
Draft Angles
Investment casting produces near-net-shape parts with excellent dimensional accuracy. Draft angles are typically not required.
Investment Casting Advantage
Unlike die casting or injection molding, investment casting uses a disposable wax pattern and ceramic shell that can be broken away. This means zero draft angles are typically required, allowing for complex geometries including undercuts, vertical walls, and intricate details.
Radii and Fillets
Proper radii prevent stress concentrations and improve flow characteristics:
Internal Corners
Minimum radius of 0.5mm. Ideal: 1-2mm or larger for improved strength and mold life.
External Corners
Recommended radius of 0.25-0.5mm to prevent sharp edges and improve finish quality.
Undercuts and Complex Features
Complex Geometries Supported
- • Undercuts are fully supported - no tooling limitations like die casting
- • Internal cavities, holes, and complex passages can be achieved using ceramic cores
- • Near-net-shape capability reduces or eliminates secondary machining
- • Ideal for intricate details including logos, text, and fine features
Tolerances
Standard tolerances for investment casting:
- • Linear dimensions: ±0.13mm for first 25mm, ±0.05mm per additional 25mm
- • Hole diameters: ±0.05mm to ±0.13mm depending on size
- • Surface finish: Ra 3.2μm (125μin) as-cast, better with post-processing
Common DFM Issues
Excessive thin walls
Impact: Incomplete metal flow, porosity, weak sections
Solution: Maintain minimum 0.75mm wall thickness for most materials
Sharp internal corners
Impact: Stress concentrations, potential crack initiation points
Solution: Add minimum 0.5mm radii to internal corners when possible
Isolated heavy sections
Impact: Shrinkage porosity, internal voids during solidification
Solution: Ensure uniform wall thickness or add feeding paths for heavy sections
Parts exceeding build volume
Impact: Cannot be manufactured in single piece
Solution: Redesign to fit within 150mm × 150mm × 150mm or split into assemblies