Material guide
Delrin vs Nylon for Bushings, Gears and Wear Parts
Delrin and nylon both make great bushings, gears and rollers, but nylon absorbs water and Delrin doesn't. Here's how they compare on strength, wear, moisture, tolerances and cost, and when to use each.
Choose Delrin (acetal) for precision parts and anything wet or humid: it barely absorbs water, so it holds tight tolerances. Choose nylon (especially cast or oil/MoS2-filled nylon) for heavy loads, impact, abrasion and big parts, where its toughness and lower cost in large sizes win and a little dimensional change doesn't matter.
The short version
Delrin and nylon are the two workhorses for bushings, gears, rollers, sheaves and wear pads. The single biggest difference is water. Nylon absorbs moisture from the air and swells slightly, getting tougher but softer. Acetal stays dry, stiff and dimensionally stable. Most choices between them come down to whether the part needs precision or needs to take a beating.
| Delrin (acetal) | Nylon 6/6 and cast nylon 6 | |
|---|---|---|
| Moisture absorption | ~0.2% (very low) | ~2–3% in normal air, more when wet |
| Dimensional stability | Excellent | Fair; grows with humidity |
| Tensile strength | ~10,000 psi | ~11,000–12,000 psi dry; lower when wet |
| Impact toughness | Good | Excellent |
| Abrasion resistance | Good | Very good |
| Friction | Lower, very consistent | Low; much lower with oil or MoS2 fill |
| Max service temp | ~180°F (82°C) | ~200°F (93°C) |
| Large parts available | Limited by extruded stock | Cast nylon comes in very large sizes |
| Relative cost | $$ | $–$$ |
Typical values for unfilled stock shapes. Nylon properties vary a lot with grade and moisture; confirm with the datasheet for your grade.
Moisture: the deciding factor
As nylon absorbs water, it grows slightly and its stiffness drops while its toughness rises. A nylon bushing machined to a tight fit on a dry day can bind on a humid one, and a nylon gear can shift its mesh. Acetal doesn't do this, which is why it's the default for precision parts, anything submerged or washed down, and parts in climates with big humidity swings.
If you do use nylon in a precise part, allow extra running clearance and ask your supplier about conditioning or about cast nylon grades with lower moisture uptake.
Load, impact and wear
Nylon is tougher. It absorbs shock loads that can chip or crack acetal gear teeth, and it handles abrasive, dirty environments well. Cast nylon is also available in big rods, tubes and plates, so large sheaves, wheels, wear pads and crane pads are almost always nylon. Filled grades push it further: MoS2 for wear, oil-filled for heavily loaded, slow-moving bearings that run without grease.
Bushings and bearings
- Delrin: precise fit on smooth steel shafts, wet or washdown areas, food equipment, light to moderate loads at moderate speeds.
- Delrin AF (PTFE-filled): lower friction for dry-running bushings.
- Oil-filled or MoS2-filled cast nylon: heavy loads, slow speeds, dirty or outdoor equipment, large bushings and wear pads.
Gears
Acetal gears run quietly, hold their profile and mesh, and are a favorite for precision and small-to-medium gearing. Nylon gears are tougher, more forgiving of shock loads and misalignment, and common in heavier, slower drives. Mixing them (an acetal gear running against a nylon gear) is a common trick to reduce wear and noise.
When to choose each
Choose Delrin for
- Tight-tolerance bushings, rollers and fixtures
- Wet, humid and washdown environments
- Precision gears and cams
- Threads and press fits that must stay put
- Food and beverage equipment (FDA grades)
Choose nylon for
- Heavy loads, shock and impact
- Sheaves, wheels, crane and outrigger pads
- Large parts from cast nylon stock
- Abrasive or dirty environments
- Oil- or MoS2-filled self-lubricating bearings
Tip from the counter: when a nylon part "mysteriously" stops fitting, moisture is the first suspect. If the part has to hold a tight fit, acetal usually solves it.
See also Delrin vs acetal (homopolymer vs copolymer) and Delrin vs UHMW.
Common questions
Which is stronger, nylon or Delrin?
When dry, nylon 6/6 has similar or slightly higher tensile strength than Delrin and is tougher under impact. But nylon absorbs moisture, which makes it softer and less stiff in humid or wet conditions. In real-world service, Delrin keeps its stiffness and dimensions more consistently; nylon handles shock loads and abrasion better.
Is Delrin a form of nylon?
No. Delrin is acetal (polyoxymethylene). Nylon is a polyamide. They're both tough, slippery engineering plastics used for similar parts, which is why they get confused, but they're chemically different and behave differently around water.
Is Delrin a good bushing material?
Yes, especially for precise bushings running on smooth steel shafts in wet or humid conditions, because it barely absorbs water and holds its fit. For heavy loads, slow speeds or dirty environments, oil-filled or MoS2-filled cast nylon is often the better bushing material.
How much water does nylon absorb?
Nylon 6/6 can absorb around 2 to 3% water at typical room humidity and up to roughly 7 to 8% when fully saturated, growing slightly as it does. Acetal absorbs only about 0.2%. That's why nylon parts with tight tolerances can bind or loosen as humidity changes.
What is Nylatron?
Nylatron is a family of filled nylon grades. Nylatron GS contains molybdenum disulfide (MoS2) for better wear and lower friction; Nylatron NSM and other oil-filled cast nylons are made for heavily loaded, slow-moving bearings and wear pads. Other manufacturers sell similar MoS2- and oil-filled nylons under their own names.
Values in this guide are typical figures for common unfilled grades, for general comparison only. Properties vary by manufacturer, grade, filler, and shape. Before you specify, buy or machine a material for an application, check the manufacturer's datasheet and the material certifications for the exact grade you're getting, and confirm suitability with your supplier.
Who stocks and machines it
Distributors that stock these materials and shops that machine or fabricate them, from the Stock & Shape directory.
Acetal (Delrin)
- Cope Plastics – Hiawatha Hiawatha, IA
- Interstate Advanced Materials – Portland Portland, OR
- Laird Plastics – Orlando Orlando, FL
- Piedmont Plastics – Westchester Thornwood, NY
- Ehren-Haus Industries Fort Mill, SC
- J & N Metal Products Brazil, IN
- Maximum Industries Irving, TX
- Miles Products Brunswick, OH
Nylon
- Calsak Plastics – Minneapolis Blaine, MN
- Curbell Plastics – Hartford Windsor, CT
- Laird Plastics – Tampa Tampa, FL
- Piedmont Plastics – Salt Lake City Sandy, UT
- Arctic Manufacturing Services Anchorage, AK
- Grand Traverse Machine Co. Traverse City, MI
- Pilgrim Harp Avon Lake, OH
- Seastrom Mfg. Co. Twin Falls, ID