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Implant and Instrument Materials, Grade by Grade
The standard on the drawing, the condition of the bar and the certificate that comes with it. The cross designations below are what a supplier's material buyer works from.
Standards are public material standards. They describe what a part can be released against, never a promise from a shop or from us.
Designations across ASTM, ISO and UNS
ISO 5832 parts and their ASTM counterparts are close but not identical. Name the one you release against and let the supplier buy to it.
| Material | ASTM | ISO | UNS | Usual condition | Typical use |
|---|---|---|---|---|---|
| Ti-6Al-4V ELI | F136 | ISO 5832-3 | R56401 | Annealed bar and wire | Implant |
| Ti-6Al-4V | F1472 | ISO 5832-3 | R56400 | Annealed bar and plate | Implant and instrument |
| CP titanium Grade 2 | F67 | ISO 5832-2 | R50400 | Annealed | Implant, cranial and dental |
| CP titanium Grade 4 | F67 | ISO 5832-2 | R50700 | Annealed or cold worked | Dental implants and abutments |
| 316L and 316LVM | F138, F139 | ISO 5832-1 | S31673 | Annealed or cold worked | Temporary implants, instruments |
| CoCrMo, wrought | F1537 | ISO 5832-12 | R31537 to R31539 | Annealed, warm or hot worked | Joint components, spinal rods |
| CoCrMo, cast | F75 | ISO 5832-4 | R30075 | As cast or HIP, machined after | Cast joint components |
| 17-4 PH stainless | A564 | ISO 7153-1 | S17400 | Condition A, aged H900 to H1150 | Reusable instruments |
| 420 stainless | A276 | ISO 7153-1 | S42000 | Hardened and tempered | Blades, jaws, cutting instruments |
| Nitinol | F2063 | n/a | n/a | Superelastic or shape set | Implant and instrument |
| PEEK, implant grade | F2026 | n/a | n/a | Rod and plate | Spinal cages, trials |
| UHMWPE | F648 | ISO 5834-2 | n/a | Ram extruded or compression molded | Bearing inserts and liners |
The machining side of each grade is on the home page table and in titanium, 316L and PEEK compared. For the alloy itself: Ti-6Al-4V.
Three families, three different purchases
The same shop may cut all three, but the bar, the certificate and the questions are different.
Implant grades
Released to a surgical implant standard such as ASTM F136, F138, F1537 or F2026. The standard sets chemistry, mechanical properties and often microstructure and inclusion limits. Bar comes with a certificate tied to the heat.
Common grades: Ti-6Al-4V ELI, CP titanium, 316LVM, CoCrMo, PEEK, UHMWPE, nitinol
Reusable instrument grades
Chosen to hold an edge, resist wear and survive repeated cleaning and steam sterilization. Hardness and heat treat condition matter more than implant chemistry. ISO 7153-1 lists the metals used for surgical instruments.
Common grades: 17-4 PH, 420, 440A, 304, 316L, Ti-6Al-4V
Device and equipment grades
Housings, robotic structure, fixtures and diagnostic hardware with limited or no patient contact. Ordinary commercial grades, still with a certificate and lot traceability if the device file asks for it.
Common grades: 6061 and 7075 aluminum, 303 and 304 stainless, PPSU, PEI, acetal, PTFE
More on single grades: 17-4 PH and 420 for instruments, cobalt chrome to ASTM F1537, nitinol components and PPSU, PEI and acetal.
What the mill certificate should show
The certificate is half of what you pay for in an implant bar. Read it against the standard before the first lot is cut, not after.
- Standard and revisionThe material standard with its year, for example ASTM F136 and the edition it was certified to. Revisions change limits.
- Heat or lot numberThe number that is carried through every operation to your finished lot. Without it, traceability stops at the stockist.
- ChemistryMeasured values, including interstitials on titanium. F136 ELI caps oxygen at 0.13 percent and iron at 0.25 percent, which is what ELI means.
- Mechanical propertiesTensile strength, yield strength, elongation and reduction of area from the heat, against the minimums in the standard.
- Microstructure and inclusionsWhere the standard requires it: titanium microstructure, grain size and inclusion rating for 316LVM, freedom from alpha case.
- Melt and process routeVacuum melting for 316LVM and the process route for cobalt chrome, since the standard depends on them.
- Certificate typeEN 10204 3.1 or the mill equivalent, signed by the producer. A distributor certificate should attach the original, not replace it.
A material standard is not a biocompatibility claim
Releasing bar to ASTM F136 tells you the chemistry and properties of the metal. It does not tell you the finished part is biocompatible. ISO 10993-1 evaluates the device in its final form, after machining, cleaning, passivation, marking and packaging, and that evaluation belongs to the device maker.
Three machining choices feed straight into it. The coolant and cutting oil, because residues have to be removed and the cleaning validated against them. The cleaning agents, because they are residues too. And the marking and surface treatments, because they change the surface the body sees.
So the material line on the drawing is not the end of the material conversation. Ask the supplier which coolant it runs on implant work, whether it is dedicated to medical parts and what the cleaning process removes. Our supplier checks record which materials and finishing steps a shop says it runs. Coolant, cleaning and residue limits are part of your own qualification.
The standard for each implant alloy is published by ASTM, for example ASTM F136 for Ti-6Al-4V ELI.
Questions about materials
Do I need Ti-6Al-4V ELI or will standard Ti-6Al-4V do?
ELI to ASTM F136 is the usual choice for implants, because the lower interstitial content improves fracture toughness. Standard Ti-6Al-4V to F1472 is used for some implants and many instruments. It machines the same way, so the price difference is material and certificate, not machining.
Can a supplier substitute a grade it has in stock?
Not without your approval. On a device component the material and its standard are part of the design output, so a substitution is a change that goes through your change control, even when the grades are close equivalents.
Is 17-4 PH an implant material?
No. It is an instrument material, valued for strength and hardness after aging. Implant stainless is 316L or 316LVM to ASTM F138, and most permanent implants use titanium or cobalt chrome.
Who is responsible for biocompatibility?
The device maker. A material released to an implant standard is a starting point, but ISO 10993-1 evaluates the finished device, including residues from machining, cleaning and marking. Tell the supplier which coolants and cleaning agents your evaluation assumed.
Grade and standard decided?
Send the drawing with the material standard on it. We match it with up to 3 suppliers that run that grade and reply within 24 business hours. The route after the bar: processes. Where each grade ends up: applications.