Guides / Sourcing
Autoclave, EtO, Gamma and VHP: What Each One Does to a PEEK Part
September 26, 2026
Sources: manufacturer datasheets and published standards. See editorial standards.
A device team rarely picks a sterilization method to suit the plastic. The method is set by the hospital’s central sterile workflow, the device’s own validation, or a specific concern such as heat sensitive components elsewhere in the assembly, and the PEEK part has to hold up to whatever that method turns out to be. The methods do not treat PEEK the same way, and a part spec that names a grade but not a sterilization cycle is missing the variable that decides whether the part lasts.
Steam Autoclave: PEEK’s Strongest Method
Steam autoclave, typically at 121 to 134 degrees C, is where unfilled PEEK performs best of the common medical polymers. It resists hydrolysis far better than PEI or polysulfone, both of which lose strength measurably over repeated steam cycles. A well specified unfilled PEEK part can run hundreds of autoclave cycles with no meaningful change in strength or fit, which is the main reason reusable PEEK hardware exists in the first place. The wider chemical resistance picture, autoclave included, is in PEEK chemical resistance.
Ethylene Oxide: The Residual Is the Real Concern
EtO sterilizes at a lower temperature than autoclave, which makes it common for components that cannot take steam heat. PEEK itself tolerates the EtO exposure without much issue. The concern is residual ethylene oxide and its byproducts absorbing into the material and needing to off gas afterward. Aeration time is not a fixed number, it depends on the part’s wall thickness and geometry, and it has to be validated for the specific part rather than copied from a similar one. This is a validation and documentation question as much as a material one, and it belongs in the device’s own sterilization validation, not assumed from the resin datasheet alone.
Gamma: Dose Limits Are Grade Specific, Not PEEK’s Weak Point
Gamma irradiation is where some other polymers, notably certain grades of polypropylene and PTFE, show visible embrittlement or discoloration at typical sterilization doses. PEEK holds up comparatively well against a standard gamma dose. That said, “PEEK tolerates gamma well” is not a blanket pass for every PEEK grade at every dose. Filled and bearing grades, and any grade exposed to a nonstandard or repeated gamma dose, should be checked against the resin supplier’s own irradiation data before it is assumed safe, the same way any dose sensitive component would be checked.
Vaporized Hydrogen Peroxide: A Lower Temperature Alternative
VHP is used where a device cannot take EtO’s cycle time or autoclave’s heat, often for assemblies with sensitive electronics or coatings alongside the PEEK component. PEEK is chemically resistant to hydrogen peroxide at the concentrations VHP uses, so the polymer itself is not the limiting factor. As with EtO, the practical questions are about the whole assembly, not the plastic alone: does the chamber cycle reach every surface, and does the assembly’s other materials tolerate the exposure as well as the PEEK does.
Comparing the Four Methods
| Method | Effect on PEEK | Main thing to check |
|---|---|---|
| Steam autoclave | Minimal degradation across hundreds of cycles | Confirm cycle temperature and count against the resin datasheet |
| Ethylene oxide (EtO) | Little direct effect on the polymer | Residual aeration time, validated per part geometry |
| Gamma irradiation | Generally tolerant compared with other polymers | Dose limit checked per grade, not assumed from PEEK generally |
| Vaporized hydrogen peroxide (VHP) | Chemically resistant at typical concentrations | Chamber exposure reaching every surface of the part |
What Changes Over Repeated Cycles, Not the First One
A part that survives one cycle of any of these methods usually survives the first ten. The failures that show up in the field are almost always a cumulative effect: hundreds of autoclave cycles on a part that was never stress relieved after machining, or a gamma dose applied a second time because the part was resterilized after an initial failed shipment. Stress relief before the part enters service reduces the first kind of failure; see annealing PEEK parts for how that step fits into the process.
What to Put on the RFQ
Name the sterilization method, the cycle temperature or dose, and the expected number of cycles over the part’s service life. A shop quoting blind on “medical grade, autoclavable” without those numbers is quoting a different part than the one that actually needs to ship.
Send the drawing with the sterilization method and cycle count, and we match you with shops that already ask these questions before they quote.
Frequently asked questions
Is autoclave the best sterilization method for PEEK parts?
For repeated use PEEK components it usually is. Unfilled PEEK resists the steam and heat of autoclave far better than PEI or polysulfone, which is why reusable PEEK hardware is built around that cycle rather than around EtO or gamma.
Does gamma sterilization degrade PEEK?
Less than it degrades many other polymers, but dose limits are still grade specific and should be checked against the resin supplier's data rather than assumed safe by default, especially for filled or bearing grades.
What happens if EtO residuals are not aerated properly on a PEEK part?
Ethylene oxide can remain absorbed in the material and off gas later, which is a documentation and validation issue rather than a PEEK weakness specifically. Aeration time has to be validated per part geometry and wall thickness, not assumed from a generic cycle.
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