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Delrin Comparisons — POM-H vs. Acetal Copolymer, Nylon & PEEK

Delrin (POM-H acetal homopolymer) is most often compared to three materials: acetal copolymer (the alternative POM variant), nylon 66 (the other dominant precision plastic for gears and bearings), and PEEK (the premium engineering thermoplastic for demanding environments). Each comparison involves different trade-offs, and the right material depends on specific application requirements. This page links to the dedicated versus pages and summarizes the key differentiators for each comparison.

At a glance:

  • Delrin vs. acetal copolymer: same material family, different chain structure — hot water and porosity are the decision axes
  • Delrin vs. nylon 66: both excellent for gears; Delrin wins on dimensional stability in humidity, nylon wins on temperature range
  • Delrin vs. PEEK: Delrin is dramatically cheaper; PEEK wins above 185°F or in chemical resistance requirements
  • Delrin vs. UHMW-PE: UHMW is softer and more abrasion-resistant; Delrin is stiffer and more precise
  • Delrin vs. polycarbonate: Delrin has better chemical resistance and fatigue; PC has better impact and transparency

Delrin vs. Acetal Copolymer (POM-H vs. POM-C)

The most important comparison in the acetal family. Many engineers and purchasing groups treat these as interchangeable — they are not.

Choose Delrin (POM-H) when:

  • Gear tooth fatigue life is the governing design constraint
  • High-cycle snap-fit or fatigue-loaded parts
  • Maximum stiffness and heat deflection temperature within the acetal family
  • Print or specification calls out "Delrin" by name or requires POM-H specifically

Choose acetal copolymer when:

  • Hot water, steam, or sustained moisture exposure above 60°C
  • Large-diameter rod (>3") where centerline porosity is unacceptable
  • Alkaline chemical environments
  • FDA compliance without requiring specific "SA" grade designation

See the dedicated Delrin vs. acetal copolymer comparison for the complete analysis.

Delrin vs. Nylon 66 (PA66)

Nylon 66 and Delrin are the two most specified plastics for precision gears, bushings, and structural machined parts. They compete directly in most applications.

Choose Delrin when:

  • Dimensional stability in varying humidity is critical (instrumentation, precision mechanisms)
  • Lower moisture absorption is needed in the finished part
  • Wet-condition mechanical properties must remain predictable
  • Fatigue life is the primary constraint

Choose nylon 66 when:

  • Higher continuous service temperature (up to 250°F) is needed
  • Shock absorption and toughness take priority over stiffness
  • Moderate cost is the primary driver and humidity variation is acceptable
  • Part will be lubricated with oil or grease (nylon absorbs lubricant and performs well)

Delrin vs. PEEK

PEEK is the high-performance comparison: significantly more capable than Delrin in temperature and chemical resistance, but 10–15× more expensive.

Choose Delrin when:

  • Application temperature is below 185°F continuous
  • Cost is a primary consideration
  • Excellent machinability is important
  • Chemical environment is compatible with POM (no strong acids, no hot water above 60°C)

Choose PEEK when:

  • Temperature exceeds 200°F continuously
  • Strong chemical exposure (acids, aggressive solvents)
  • Regulatory requirements demand USP Class VI or higher (PEEK offers broader certifications)
  • V-0 flame rating is required

For the full high-performance comparison, see PEEK vs. Delrin.

Delrin vs. UHMW Polyethylene

UHMW-PE (ultra-high molecular weight polyethylene) is often a cost-driven alternative to Delrin in wear-strip and bearing applications.

Choose Delrin when: tight dimensional tolerances are required; high-load compressive applications (Delrin has 3–4× higher compressive strength); precision machined mechanical components.

Choose UHMW-PE when: maximum abrasion resistance in sliding contact; chemical inertness is primary; lower cost is the decision driver; noise and vibration damping matter.

Delrin vs. Polycarbonate (PC)

Choose Delrin when: fatigue life and chemical resistance matter; bearing and wear applications; gears and precision mechanisms.

Choose polycarbonate when: optical clarity is needed; impact resistance is the primary design driver; applications involving impact loads (guards, covers, transparent lenses).

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More related guides

Versus pages

Material hubs

Frequently asked questions — Delrin FAQ