Guides / Sourcing
The PEEK Aerospace Drawing Checklist
September 26, 2026
Sources: manufacturer datasheets and published standards. See editorial standards.
A PEEK drawing that would be complete for an industrial part is often missing exactly the lines that matter in aerospace. None of what follows is exotic. It is a short list of details that change the quote, change what the shop plans for, and change whether the part comes back right the first time.
Most of these gaps do not show up as a rejected part. They show up as a follow-up email asking a question that should have been on the drawing, a quote that assumes the wrong grade, or a part that measures correctly in the shop and wrong once it is installed. Closing them at the drawing stage costs nothing and saves the round trip.
Grade
Name the grade, not just “PEEK.” Unfilled, GF30 or CF30 machine differently, expand differently and carry load differently, and a drawing that just says PEEK leaves the shop guessing at a decision that belongs to the design, not the quote. The trade-offs between grades are covered in which PEEK grade to specify.
Tolerance, with the temperature it applies at
This is the line most PEEK drawings skip, and it is the one that causes the most disputes later. PEEK expands roughly four times more than steel per degree, so a tight fit specified without a service temperature is only half specified. State the temperature a critical dimension has to hold at, not just the tolerance. The reasoning, and realistic tolerance numbers to start from, are in PEEK machining tolerances.
Stress relief callout
If the part has thin walls, a deep pocket, a long slender shape or a bore that has to hold roundness, say so and call for stress relief between roughing and finishing. Leaving this off does not make the part cheaper; it just moves the stress relief step into service, where it shows up as warping instead of as a line item on the quote.
Traceability and AS9100, if the program needs it
Where your quality flow-down requires it, say so explicitly: AS9100 shop, material lot traceable to the resin producer, certificate of conformance supplied with the parts. Where it is not a program requirement, ask for traceability anyway. It costs the shop nothing to provide and it is the detail that actually protects you if a lot is ever questioned. What the certificate does and does not cover on its own is worth reading before you write the requirement, in AS9100 and PEEK machining.
Surface finish
State it as a number, not a word. “Smooth” means different things to different shops. Ra 0.8 µm is a normal finishing pass; Ra 0.4 µm needs a sharp polished tool and light passes, and filled grades will show fibre at the surface regardless of how fine the finish is.
Flammability, smoke and toxicity, only where it applies
FST testing is a real requirement for materials used in a pressurized cabin interior, where occupant safety in a fire scenario is the entire point of the test. It is not a blanket aerospace requirement. A bracket in an unpressurized bay, a piece of ground support equipment, or a fixture used in manufacturing does not need FST testing unless a specific program specification calls for it on that part. Asking for FST data on a part that will never see the cabin adds cost and lead time for a test that answers a question nobody is asking. Asking for it on a part that will sit in the cabin, and not asking, is the opposite mistake. Check the installation location before writing the requirement either way.
Putting it together
A complete PEEK aerospace drawing answers six questions before the shop ever quotes it: which grade, what tolerance at what temperature, whether stress relief is called for, what traceability the program needs, what surface finish in a number, and whether FST applies to where the part actually lives. Six lines, and most of the disputes that come up after a part ships trace back to one of them being missing rather than to the shop doing something wrong.
None of these six require a redesign or a long specification review. They are lines an engineer who has machined PEEK before writes automatically and a shop that has not seen much of it forgets to ask about until the quote is already wrong. Getting them onto the drawing before the RFQ goes out is the cheapest step in the whole process.
The general version of this checklist, for any PEEK part, is in our guide to custom PEEK parts.
Send the drawing with these six answered, and we match you with shops that will quote it accurately the first time instead of asking the same six questions back over email.
Frequently asked questions
Does every PEEK aerospace part need FST testing?
No. Flame, smoke and toxicity testing is a cabin-interior requirement tied to occupant safety in an enclosed space. A bracket or bushing outside the cabin, in an unpressurized bay or on ground support equipment, does not carry that requirement unless a specific program spec calls for it.
What is the single most useful line to add to a PEEK aerospace drawing?
The temperature at which a critical tolerance applies. PEEK expands roughly four times more than steel per degree, so a tight fit specified without a temperature is not fully specified, whatever else the drawing says.
Do I need to specify AS9100 on every PEEK aerospace RFQ?
Only where your program's quality flow-down requires it, typically flight hardware under a manufacturer's own quality system. For non-flight parts, traceability and inspection requirements written out explicitly often matter more than the certificate itself.
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