Explore Delrin and Its Material Properties

What Is Delrin?

Delrin® is DuPont’s trade name for polyoxymethylene homopolymer (POM-H) — one of the most widely specified engineering thermoplastics in the world. Known generically as an acetal homopolymer, Delrin® combines high mechanical strength, exceptional dimensional stability, low friction, outstanding wear resistance, and excellent fatigue endurance in a material that machines with the precision of metal but at a fraction of its weight.

First commercialized by DuPont in 1960, Delrin® has become a go-to material for engineers designing precision mechanical components that must perform reliably under demanding loads, wear conditions, and environmental exposures — in industries ranging from automotive and electronics to medical devices and industrial equipment.

Key Material Properties of Delrin® (POM-H)

High Strength and Stiffness: Delrin® is the stiffest unreinforced engineering thermoplastic available — with tensile strength typically in the range of 68–72 MPa and a flexural modulus of approximately 2,800–3,100 MPa. Its strength is retained over a wide operating temperature range of -40°C to 120°C.

Low Friction and High Wear Resistance: Delrin®’s naturally smooth, low-energy surface provides a low coefficient of friction without requiring external lubrication — essential for gears, bearings, and sliding mechanisms that must operate quietly and efficiently with minimal wear over long service lives.

Excellent Dimensional Stability: Delrin® has very low moisture absorption (< 0.25%), meaning components maintain their dimensions in humid or wet environments — unlike nylon, which can swell significantly with moisture uptake.

Fatigue and Creep Resistance: Delrin® exhibits outstanding resistance to cyclic fatigue — sustaining millions of load cycles without crack initiation — making it an ideal choice for snap-fit closures, springs, and cyclically loaded mechanical elements.

Chemical Resistance: Delrin® resists hydrocarbons, solvents, alcohols, neutral chemicals, and motor fuels. It is susceptible to strong mineral acids, oxidizing agents, and chlorinated solvents.

Machinability: Delrin® is one of the easiest engineering plastics to machine — turning, milling, drilling, and threading cleanly to tight tolerances with standard metal-working tooling and practices.

POM-H vs. POM-C: Homopolymer vs. Copolymer Acetal

Delrin® (POM-H homopolymer) offers superior room-temperature mechanical strength, stiffness, and hardness compared to acetal copolymer (POM-C). However, copolymer acetal provides better thermal stability at continuously elevated temperatures, improved resistance to hot water and alkaline environments, and lower centerline porosity in thick sections — making it the preferred choice for some chemical processing and hot-water applications. For the most demanding mechanical performance, Delrin® (POM-H) remains the benchmark.

Testing of Delrin® (POM) Materials

Tensile Testing (ASTM D638): Standard characterization of tensile strength, elongation, and modulus. Testing at both room and elevated temperatures is important for applications subject to thermal exposure.

Flexural Testing (ASTM D790): Bending stiffness and flexural strength for structural and semi-structural components.

Fatigue Testing (ASTM D7791): S-N curve generation for snap-fit and cyclically loaded applications.

Wear and Friction Testing (ASTM D3702, G99): Tribological performance characterization for bearings, gears, and sliding mechanisms.

Creep Testing (ASTM D2990): Long-term dimensional stability under sustained mechanical load — critical for structural and assembly retention applications.

Water Absorption (ASTM D570): Confirming Delrin®’s dimensional stability advantage over nylon under humid and immersion conditions.

Impact Testing (ASTM D256 — Izod): Notched impact resistance for design of snap-fit features and shock-exposed components.

Flammability (UL 94, ASTM D635): Standard-grade Delrin® is UL 94 HB-rated; flame-retardant grades that achieve V-0 are available for electrical and electronic applications.

Industry Applications

Automotive: Door lock and window lift mechanisms, fuel sender units, gear selector bushings, seatbelt components, and fluid system connectors use Delrin® for its combination of strength, fatigue endurance, low friction, and fuel/oil resistance.

Electronics and Electrical: Connector housings, switch components, coil bobbins, and precision electronic device housings specify Delrin® for its dimensional stability, electrical insulation properties, and ease of precision molding.

Industrial Machinery: Conveyor system components, pump internals, valve seats, metering system gears, and wear strips use Delrin® wherever metal replacement with a self-lubricating, dimensionally stable polymer provides cost or performance advantages.

Medical Devices: Delrin® medical-grade materials are used for drug-delivery device components, surgical instrument handles, and diagnostic equipment housings — where dimensional precision, sterilization compatibility, and regulatory compliance are required.

Consumer Products: Zippers, buckles, snap closures, fountain pen mechanisms, and precision consumer device components use Delrin® for its tactile quality, durability, and snap-fit performance.

Conclusion

Delrin® (POM-H) — combining high tensile strength, low friction, exceptional dimensional stability, fatigue endurance, and ease of machining — stands as the benchmark unreinforced engineering thermoplastic for precision mechanical components across automotive, electronics, industrial, medical, and consumer applications. Selecting the right acetal grade for the geometry, thermal environment, and chemical exposure of an application is what determines whether a component delivers long-term dimensional precision, wear resistance, and load-bearing reliability — making material specification as critical as design itself. When paired with comprehensive testing under ASTM-standardized mechanical, tribological, thermal, and environmental protocols, Delrin® components can be fully characterized and validated to meet the most demanding performance and regulatory requirements.

Why Choose Infinita Lab for Delrin® / POM Testing?

Infinita Lab offers comprehensive Delrin® and acetal (POM) testing services across its network of 2,000+ accredited labs in the USA, covering mechanical, tribological, thermal, and environmental characterization. From advanced metrology to standardized ASTM testing, we give clients unmatched flexibility and scale — you’re not limited by geography, facility, or methodology.

Looking for a trusted partner to achieve your research goals? Schedule a meeting with us, send us a request, or call us at (888) 878-3090 to learn more about our services and how we can support you. Request a Quote.

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