POM / Delrin vs Nylon (PA6)
POM (Delrin) and Nylon (PA6) are the two default machinable engineering plastics, and the choice usually comes down to dimensional stability versus toughness. The deciding question is almost always how much moisture and impact the part will see.
The verdict
Choose POM / Delrin when you need tight, stable tolerances, low consistent friction and clean machinability — precision gears, bushings and wear parts in dry or wet service. Choose Nylon (PA6) when the part takes impact, abrasion or shock, when you need to weld or bond it, or when cost is critical. The split: POM for stability, Nylon for toughness and wear.
Side-by-side data
| Property | POM / Delrin | Nylon (PA6) |
|---|---|---|
| Category | Engineering Plastic | Engineering Plastic |
| Density (g/cm³) | 1.41 | 1.14 |
| Tensile strength (MPa) | 70 | 80 |
| Yield strength (MPa) | 65 | 80 |
| Elongation (%) | 40 | 50 |
| Hardness | R120 | R120 |
| Max service temp (°C) | 90 | 110 |
| Machinability | ●●●●● | ●●●●● |
| Corrosion resistance | ●●●●● | ●●●●● |
| Relative cost | ●●●●● | ●●●●● |
| Thermal cond. (W/m·K) | 0.31 | 0.25 |
| Typically used for | Precision low-friction machined parts | Gears, bushings & wear parts |
Which should you choose?
Choose POM / Delrin if…
- You need tight tolerances that hold — POM barely absorbs moisture, so parts stay dimensionally stable in humid or wet service.
- The part is a precision gear, bushing or sliding element needing low, consistent friction and good fatigue/creep resistance.
- You're machining to a fine finish — Delrin cuts cleanly and predictably with low scrap, even on complex geometry.
- Stiffness and hardness matter more than impact toughness, and loads are steady rather than shock.
- You want self-lubricating behavior without filler additives.
Choose Nylon (PA6) if…
- The part takes impact or shock loading — PA6 is far tougher and more forgiving than the notch-sensitive, brittle-failing POM.
- Abrasion and sliding wear dominate, especially against metal — Nylon wears very well and tolerates occasional dry running.
- You can run filled or oil-impregnated grades (MoS2 or oil-filled PA6) to extend life in bushings, wear pads and rollers.
- Budget matters: PA6 is generally cheaper stock, and it welds and bonds far more readily than POM.
- You need higher short-term temperature capability and good resistance to oils and greases.
Key differences that matter
- Moisture is the deciding factor: PA6 absorbs water, which swells parts and shifts dimensions and stiffness — POM stays dimensionally stable, which is why precision gears default to Delrin.
- Toughness vs. stiffness: Nylon is tougher and absorbs impact; POM is stiffer and stronger in fatigue but notch-sensitive and can fail more abruptly.
- Machinability favors POM: Delrin is one of the easiest plastics to machine to tight tolerance with a clean finish; Nylon is grabbier and more affected by its moisture state.
- Bonding and welding favor Nylon: POM's low surface energy makes it notoriously hard to glue or paint, while PA6 welds and bonds far more readily.
- Wear and cost: Nylon (especially filled grades) excels at abrasion and is usually cheaper; POM gives lower, more consistent friction for self-lubricating motion parts.
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Open the Material SelectorGet a Quote →Frequently asked questions
Is POM / Delrin stronger than Nylon (PA6)?
It depends on the metric. Dry POM is stiffer, harder and has better fatigue and creep resistance, so it 'feels' stronger for precision loaded parts. But Nylon is significantly tougher with higher impact strength, so it wins where shock, snagging or sudden loads occur. POM is also notch-sensitive and can fail abruptly.
Which is cheaper, Delrin or Nylon?
Nylon (PA6) is usually the cheaper raw material and stock shape. POM commands a premium, partly for its machinability and stability. For high-volume machined precision parts, though, POM's faster, cleaner cutting and lower scrap rate can offset the higher material cost.
Which one absorbs water, and why does it matter?
Nylon (PA6) absorbs a meaningful amount of moisture; POM absorbs very little. As PA6 takes on water it swells, loosens tolerances and becomes tougher but less stiff. That's the main reason precision gears, bushings and tight-fit parts in humid or wet service default to Delrin.
Can I glue, weld or paint these plastics?
Nylon bonds, welds and paints relatively well. POM is the opposite — its low surface energy makes adhesives and coatings adhere poorly without aggressive surface treatment. If your design relies on bonding, welding or painting, lean toward Nylon or plan for mechanical fastening with POM.
Which is better for gears and bushings?
Both are classic choices. Use POM/Delrin for precision gears needing tight tolerances, low stable friction and dimensional stability. Use Nylon for gears and bushings that see impact, abrasion or run lubricated — especially filled or oil-impregnated PA6 grades that boost wear life.
Property values are typical/nominal figures for early-stage guidance only and vary by temper, grade, supplier and heat treatment. Confirm critical specifications against a certified datasheet or with an mfgiq engineer before production.