Wall thickness in die casting: what is the rule?

Typically 1.5–4 mm in aluminium, uniform where possible. Thick sections trap porosity; very thin ones do not fill.

Draft in die casting: what is the rule?

About 1–3° on walls. The part must release from the die.

Radii in die casting: what is the rule?

Use generous fillets (at least about 1 mm) instead of sharp corners. Sharp corners cause cracks and die wear.

Machining allowance in die casting: what is the rule?

Leave about 0.25–0.75 mm on faces that will be machined. The cast skin is the most accurate and dense; machining must not cut too deep.

Volume in die casting: what is the rule?

Die tooling is expensive; die casting usually needs thousands of parts. The cost per part falls only after the die is paid for.

Die casting: design rules

Injecting molten aluminium, zinc or magnesium into a steel die; only pays off at volume.

Typical tolerance

Typical: about ±0.1–0.25 mm on small features; machine critical faces after casting.

Files to send

STEP of the part and a drawing marking machined faces and tolerances.

Common materials

Aluminium alloys (A380), zinc (Zamak), magnesium.

The rules, with reasons

Wall thickness. Typically 1.5–4 mm in aluminium, uniform where possible. Why: Thick sections trap porosity; very thin ones do not fill.
Draft. About 1–3° on walls. Why: The part must release from the die.
Radii. Use generous fillets (at least about 1 mm) instead of sharp corners. Why: Sharp corners cause cracks and die wear.
Machining allowance. Leave about 0.25–0.75 mm on faces that will be machined. Why: The cast skin is the most accurate and dense; machining must not cut too deep.
Volume. Die tooling is expensive; die casting usually needs thousands of parts. Why: The cost per part falls only after the die is paid for.

Before you ask for a quote

Alloy
Annual quantity
STEP and drawing
Machined faces
Surface finish and coating
Porosity requirements

Common mistakes

Ordering a die for a few hundred parts
No draft
Sharp inside corners
Expecting machined tolerances from the cast surface

Agents and scripts can check a design automatically with the check_design MCP tool or POST /api/design-rules. How to connect.

Request a quote Find manufacturers

Typical rules of thumb, not a guarantee. The manufacturer's own design guidelines override them: ask for them and check your design against both before ordering.