HUASHENG PRECISION · Updated September 17, 2026
PEEK vs PEI (ULTEM): A Grade-Based Machining Selection Guide
PEEK and PEI are material families, not interchangeable specifications. Compare the actual stock grade, reinforcement and exposure conditions before choosing a machined part material. ULTEM is SABIC’s brand for a family of PEI materials, including specialised formulations.
Review the requirements
Swipe horizontally to read the table.
| Decision | PEEK candidate | PEI / ULTEM candidate |
|---|---|---|
| Grade and reinforcement | Identify the exact supplier grade and whether unfilled, glass-filled or carbon-filled. | Identify the exact PEI or blend grade; do not treat all ULTEM grades as unfilled PEI. |
| Heat and load together | Check the grade data for the relevant test method, time and load. | Compare data under matching conditions; a single temperature figure is not a part design limit. |
| Cleaning or sterilization | Provide chemical, concentration, temperature and planned cycles for grade-specific review. | Review the intended grade and cycle conditions; healthcare grades cannot be reduced to one universal cycle limit. |
| Appearance | Confirm colour, filler and acceptable machining marks on the actual stock. | Where translucency matters, confirm grade, wall thickness and the required optical outcome. |
| Cost of the machined part | Compare stock availability, bought size, machining, scrap and required documentation. | Compare the same geometry and quantity; a fixed family-to-family price ratio is not reliable. |
Read comparable datasheet values
A continuous-use rating, a short-term heat-deflection result and a glass-transition temperature describe different things. Do not rank materials by mixing those figures. Record the property, method and test conditions beside each candidate grade; obtain supplier clarification where the intended exposure is not covered.
Specify machined-stock provenance
Name the stock producer, grade, reinforcement and any substitutions permitted. A resin datasheet does not identify the provenance or condition of a supplied rod or plate. Include required material documentation and ask how the proposed stock will be identified in the quotation.
Example: a cleaned instrument housing
If the design needs a housing to withstand repeated cleaning, list the cleaner and the complete cleaning cycle before discussing PEEK versus PEI. Identify fastening loads, wall geometry and appearance requirements as separate checks. Qualification belongs to the finished design; no unlimited cleaning or sterilization life is assumed here.
Make the quotation comparison usable
Send the same drawing revision and quantity for both candidate grades. Ask for any changes to stock size, machining approach, finish or inspection to be identified. If the design has not approved a substitution, mark the alternative as a comparison option rather than permission to change the order.
Primary technical references
References do not imply that we hold a certification or approval. Check the named grade and applicable conditions.
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