Is Delrin the same as acetal?

Delrin is a brand of acetal homopolymer. 'Acetal' and 'POM' cover both homopolymer and copolymer grades, which are similar but not identical.

POM or nylon for gears?

POM absorbs almost no water, so it keeps its size, and has lower friction. Nylon is tougher and takes shock loads better but swells with moisture. For precise small gears POM is often preferred.

What temperature can POM take?

About 90–100 °C continuously and somewhat more for short periods. Above that, choose a higher-temperature plastic such as PEEK or PPS.

POM (Delrin, acetal): properties, machining and uses

POM, also called acetal or by the brand name Delrin, is a stiff, strong engineering plastic with low friction and very low moisture absorption. Parts keep their size, slide smoothly and machine to close tolerances, so POM is used for gears, bushes, rollers, clips and valve parts.

Quick facts

Type: Semi-crystalline engineering thermoplastic
Density: About 1.41 g/cm³
Tensile strength: About 60–70 MPa
Continuous use: Up to about 90–100 °C
Moisture absorption: Very low; sizes stay stable
Moulding shrinkage: About 1.8–2.2%

Homopolymer or copolymer?

	Homopolymer (e.g. Delrin)	Copolymer
Strength and stiffness	Slightly higher	Slightly lower
Chemical and hot-water resistance	Good	Better
Centre porosity in thick rods	More likely	Less likely
Typical use	Gears, high-load small parts	General parts, thick sections

Typical uses

Gears, sprockets and cams
Bushes, bearings and wear strips
Rollers, wheels and conveyor parts
Clips, fasteners and snap fits
Pump and valve parts, food-machine parts (food grades)

Working with it

Machines very well with sharp tools; holds close tolerances
Injection moulds well; allow for its high shrinkage
Hard to glue; use mechanical fixing or snap fits
Not for strong acids or long exposure to sunlight (unless UV stabilised)

Need parts made in POM (Delrin, acetal)?

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Questions

Is Delrin the same as acetal?: Delrin is a brand of acetal homopolymer. 'Acetal' and 'POM' cover both homopolymer and copolymer grades, which are similar but not identical.
POM or nylon for gears?: POM absorbs almost no water, so it keeps its size, and has lower friction. Nylon is tougher and takes shock loads better but swells with moisture. For precise small gears POM is often preferred.
What temperature can POM take?: About 90–100 °C continuously and somewhat more for short periods. Above that, choose a higher-temperature plastic such as PEEK or PPS.

The figures on this page are typical values for guidance, written by Diemeco from standard engineering practice. They are not a specification: confirm grades and properties with the relevant standard or the supplier's mill test certificate, and tolerances with your workshop. Last checked 15 October 2026.