Medical device machining is the most demanding precision work outside aerospace. Surface finish, traceability, and material certification all matter equally.
Common Medical Materials
Titanium Grade 5 (Ti-6Al-4V ELI)
Bone implants, dental, joint replacements.
- ELI = Extra Low Interstitials (lower oxygen content for biocompatibility)
- Same machining as aerospace Ti-6Al-4V but tighter cleanliness
Stainless 316L
Surgical instruments, screws, plates.
- L = low carbon for weldability and corrosion resistance
- ASTM F138 medical-grade specification
CoCrMo (Cobalt-Chromium-Molybdenum)
Hip and knee replacement bearings, dental.
- ASTM F75 forged, F799 wrought
- Very hard (35-45 HRC), abrasive — tough on tools
PEEK (Polyetheretherketone)
Spinal implants, dental, sterilizable instruments.
- Implant-grade PEEK is ASTM F2026
- Special PCD tools for production
Surface Finish Requirements
| Application | Required Ra |
|---|---|
| Bone-contact surface (osseointegration) | 0.5-1.5 µm (rougher = better bone bond) |
| Articulating surface (joint) | < 0.05 µm (mirror finish for low wear) |
| Instrument blade edge | < 0.1 µm |
| Internal screw thread | 0.4-0.8 µm |
Tooling Implications
- Solid carbide micro end mills — Sub-1mm diameter, polished or DLC coated
- Submicron carbide drills — For Ti-6Al-4V deep holes
- Ground form tools — Custom for thread profiles, undercuts
- Diamond tooling — PCD for PEEK, CVD diamond for cobalt-chrome
- Diamond grinding wheels — Final finishing on cobalt-chrome bearings
Quality Standards
- ISO 13485 — Medical device quality management
- FDA 21 CFR 820 — US quality system regulation
- ASTM F-series — Material specifications
- USP Class VI — Biocompatibility for plastics
Traceability
- Material lot tracked per part
- Cutting tool serialized and tracked
- Cleanliness validation (passivation for stainless, anodization for titanium)
- Final dimensional + surface inspection on every part (no sampling)
Common Operations
- Bone screw threads — Tapped or rolled, often custom thread profiles
- Hex socket recesses — Forged or broached
- Knurling for grip — Custom diamond-pattern knurls
- Cannulated drilling — Through-bone screws need axial holes
For medical-grade tooling, contact us via WhatsApp +1 743-279-9499.
