CNC Machining for Medical Device Prototypes

Materials by application

Surface finish requirements

• Implants: Ra ≤ 0.4 µm typically. Lower roughness = better tissue compatibility.
• Mating surfaces (e.g. screw threads in bone): Specific texture intentional — Ra 1.6–3.2 µm to encourage osseointegration.
• Surgical instruments: Ra ≤ 0.8 µm on user-facing surfaces, electropolished or passivated.
• Disposables: As-machined acceptable unless interface critical.

Documentation you'll need

• Material certificate (EN 10204 3.1) — traceable to heat lot
• Biocompatibility documentation — for implant-grade materials, supplier mill cert is the start; final biocompatibility (ISO 10993) is the device manufacturer's responsibility
• Dimensional inspection (CMM report) — every critical feature measured
• Passivation certificate — for stainless steel, ASTM A967 or AMS 2700
• Surface finish measurement — Ra value documented per critical feature
• Lot traceability — supplier records linking your finished parts to the raw material heat lot

What CNC shops typically do NOT cover

• FDA 510(k) submission — that's the device manufacturer's job. The shop supplies the dimensional + material evidence.
• Final sterilization — typically done by the device manufacturer or a sterilization service.
• Final biocompatibility testing per ISO 10993 — done by certified test labs, not the machining shop.
• Design verification — the shop builds to your spec; verification of the design against intended use is yours.

Things to specify on the drawing

• Material grade with full spec (e.g. "Ti-6Al-4V ELI per ASTM F136")
• Surface finish callout on every critical surface
• Passivation requirement and standard (if stainless)
• "Free of cutting fluid residue" if applicable
• Cleaning + packaging requirements (cleanroom-packed, individually bagged, etc.)

Ginwate machines Ti-6Al-4V, 316L, PEEK, and other biocompatible materials with full lot traceability and passivation. See the 316L medical housing case study or request a quote.