Guides / Sourcing
PEEK or Torlon: Which One Belongs on an Aerospace Drawing
September 26, 2026
Sources: manufacturer datasheets and published standards. See editorial standards.
PEEK and Torlon show up on the same shortlist often enough that the choice between them is worth making on purpose rather than by habit. Both are high-performance thermoplastics that hold up where nylon and acetal cannot, and both get specified into aerospace hardware regularly. They are not interchangeable, and the honest version of the comparison has real trade-offs on both sides.
What each material is
PEEK (polyether ether ketone) is a semi-crystalline thermoplastic, easy to machine on standard equipment, with no post-machining cure required. Torlon is the trade name for PAI (polyamide-imide), an amorphous thermoplastic that machines well but is typically supplied, or processed after machining, through a staged thermal post-cure that develops its final mechanical properties.
Where Torlon wins
Strength and stiffness, especially hot. Torlon grades commonly reach tensile strengths well above unfilled PEEK, and the gap holds up as temperature rises. For a part under real load at elevated temperature, Torlon usually has more margin.
Creep resistance under sustained load. PAI resists creep better than PEEK at a given stress and temperature, which matters on a part that stays loaded for long periods rather than cycling.
Wear grades. Torlon’s wear-grade compounds are a mainstay in bearing and bushing applications that see both load and sliding motion at temperature.
Where PEEK wins
Cost. PEEK resin costs a fraction of Torlon’s, and the gap widens once you count Torlon’s post-cure step. For parts where PEEK’s margin is already adequate, paying for Torlon buys strength the design does not need.
No post-cure schedule. A PEEK part is finished when it comes off the machine. A Torlon part, depending on thickness, can spend days in a staged post-cure oven before it reaches its rated properties. That is real lead time on a program that is usually already tight.
Easier machining. PEEK cuts cleanly with less tool wear and fewer process controls. Torlon machines well too, but the post-cure dependency means a shop has to plan the whole job around an oven cycle, not just a spindle.
Moisture behavior. PEEK absorbs very little moisture and holds its dimensions in humid storage or service. Torlon is more moisture sensitive and often needs conditioning before it is considered dimensionally stable, which is an extra step PEEK skips.
Side by side
| PEEK (unfilled) | Torlon (PAI, typical grade) | |
|---|---|---|
| Tensile strength, room temp | 90 to 100 MPa | Roughly 150 to 190 MPa depending on grade |
| Continuous service temperature | About 250°C | About 250 to 270°C, higher for short excursions |
| Post-machining cure | None | Staged thermal post-cure, can run days on thick sections |
| Relative resin cost | Baseline | Several times higher |
| Moisture sensitivity | Low, around 0.1 to 0.5% | Higher, conditioning often specified |
| Typical lead time impact | Standard machining schedule | Extended by the cure cycle |
Numbers are typical published figures and vary by specific grade and supplier lot. Full PEEK figures, including what each property changes on a part, are in PEEK material properties.
Making the call
The decision usually comes down to one question: does the part need Torlon’s extra strength and temperature margin badly enough to pay for the resin and the schedule it brings with it? If the load case, the temperature and the creep exposure sit comfortably inside what CF30 or GF30 PEEK can carry, PEEK is the cheaper and faster part to get built, and PEEK machining cost covers what drives that price beyond the resin itself. If the part runs hot and loaded for long periods, or the design already assumes PAI-level strength, Torlon earns its price.
What does not make sense is specifying Torlon on every high-performance plastic callout because it sounds like the safer choice on paper. It is the safer choice for a specific set of conditions, and the cost and schedule it brings are real enough to check the condition before writing the spec.
Send the drawing with the load case and the service temperature, and we match you with shops that can quote either material and tell you honestly which one the part actually needs.
Frequently asked questions
Is Torlon always stronger than PEEK?
At a given temperature, most Torlon (PAI) grades beat unfilled and filled PEEK on tensile strength and stiffness, especially as temperature climbs. The gap narrows against PEEK's own filled grades, but it does not close.
Why does Torlon cost more than PEEK for the same part?
Two reasons stack together: the resin itself costs more, and most Torlon parts need a post-machining thermal cure that can run for days depending on section thickness. That cure adds oven time and lead time on top of the material price.
Can a shop just swap Torlon in for PEEK on an existing drawing?
Not without checking the design intent. Torlon needs its post-cure schedule built into the process, is more moisture sensitive, and costs enough more that swapping it in without a reason usually means someone specified it out of habit rather than need.
Need a quote for this part?
Send the drawing. We match you with up to 3 shops that cut your PEEK grade and reply within 24 business hours.
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