Investment Casting Design Guidelines

Good investment casting design begins with the finished function of the component, not with a generic process tolerance table. The drawing should identify the alloy, critical interfaces, load direction, sealing surfaces and the features that will be machined after casting.

Hengke Casting operates under ISO 9001 and IATF 16949 quality systems and supports applicable BV, DNV and PED documentation requirements for customer projects.

Wall thickness and transitions

Keep wall thickness as uniform as the application allows. Abrupt changes create hot spots and can increase shrinkage risk. Use smooth transitions and generous fillets at ribs, bosses and junctions. When a heavy section cannot be avoided, the foundry should review feeding, local chills and gating before tooling is released.

Holes, slots and internal passages

Investment casting can form complex passages, but every feature must be accessible to wax tooling and ceramic-shell removal. Very small blind holes or deep narrow slots may be more reliable when cast with machining stock and finished by drilling or milling. Internal cores require agreed location tolerances and inspection methods.

Tolerances and machining datums

Apply tight tolerances only where the part function requires them. Identify common datums for casting inspection and CNC machining. Seal faces, bearing bores, threaded ports and precision fits usually need machining allowance. The allowance must be sufficient for datum variation without creating unnecessary material or cycle time.

Alloy and heat treatment

Select the alloy from corrosion, temperature, strength and weldability requirements. Stainless grades such as CF8 and CF8M serve different environments from carbon or heat-resistant steels. State heat treatment, hardness and mechanical-property requirements on the drawing rather than relying on a trade name.

Design review checklist

• Provide 3D data and a controlled 2D drawing.
• Mark critical-to-quality dimensions and inspection frequency.
• Define surface finish and nondestructive testing only where needed.
• Confirm annual volume, lot size and traceability.
• Review tooling split, wax assembly and machining fixtures before approval.

A joint design review before tooling is the best point to remove avoidable cost and reduce production risk. Send Hengke your drawing for a manufacturability review.