Why investment casting
Arm links, gripper bodies and joint housings need low mass and high stiffness; cast pockets and ribs deliver both without multi-axis roughing.
Components
- Gripper fingers
- Joint housings
- End-effector brackets
- Sensor mounts
Materials
Aluminium, PH stainless steels, low-alloy steels.
Frequently used alloys
| Grade | Type | Standard |
|---|---|---|
| CB7Cu-1 | Precipitation-hardening stainless steel, cast 17-4 PH type 17-4 PH® type | ASTM A747/A747M |
| A356.0 | Al-Si7-Mg heat-treatable casting alloy AlSi7Mg0.3 | ASTM B618/B618M (investment castings); AA A356.0 |
| 4140 | Cr-Mo quench-and-temper steel 42CrMo4 type | SAE J404 / AISI 4140 (cast: ASTM A732 Gr. 8Q) |
| CF8M | Mo-bearing austenitic stainless steel, cast 316 type 316 type | ASTM A351/A351M, A743/A743M |
Typical requirements
Stiffness-to-weight optimisation with hollow and ribbed shapes; accurate interfaces are machined after casting.
- Low inertia design
- Precise bearing seats after machining
- Repeatable geometry
Related engineering topics
Design guidelines
Practical design-for-manufacture rules for investment castings: wall thickness, transitions, fillets, holes, cores, undercuts, ribs, bosses, draft, machining allowance and part consolidation.
Tolerances
Tolerancing of investment castings: ISO 8062-3 casting tolerance grades, VDG P 690, geometrical tolerances to ISO 1101, datum systems, machining allowance, shrinkage and distortion.
Dimensional inspection
Dimensional inspection methods for castings: hand gauges, CMM, optical 3D scanning, form measurement, datum alignment, first article inspection and series control.