POM (Acetal) Sheets and Rods: Properties, Uses and Selection

30 October, 2026 | Admin

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Short answer: POM (polyoxymethylene, also called
acetal) is a stiff, low-friction, dimensionally stable engineering
plastic. It is the usual choice for precision gears, bushes, rollers,
guides and valve parts where parts must hold their size. It is weaker
against strong acids and unsuitable for high heat.

POM machines beautifully and keeps tight tolerances, which is why it
is so common in precision mechanical parts.

Free engineering tools

Plastic weight calculator — Work out the weight of POM sheets, rods and tubes in kg
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Table of Contents

Homopolymer and copolymer

POM comes as a homopolymer and as a copolymer. The homopolymer is
generally somewhat stiffer and harder. The copolymer usually resists
chemicals and hot water better and has a more uniform centre. Properties
vary by manufacturer, so choose based on the datasheet and your
conditions.

Key advantages

high stiffness and strength for a plastic
low friction and good wear resistance
very low moisture absorption, so it holds its dimensions
excellent machinability and surface finish
good fatigue resistance, so it suits repeating loads

Limits

not suitable for strong acids and strong oxidising agents
operating temperature is moderate
it is not UV stable unless protected
it is hard to bond with ordinary adhesives

Typical uses

Application	Why POM
Precision gears	Stiff, accurate, low wear
Bushes and bearings	Low friction
Rollers and guide rails	Stable and smooth
Valve and pump parts	Dimensional stability
Jigs and fixtures	Machines accurately

POM or nylon?

Nylon is tougher and absorbs impact better but takes up moisture and
changes size. POM is stiffer, more stable and slides better, but is less
tolerant of impact. For precision and wet environments, POM often wins.
For tough, shock-loaded parts, nylon may be better. See nylon guide.

Machining tips

Use sharp tools and good chip clearance. POM can build internal
stress, so for tight tolerance parts rough-machine, allow stress to
relax, then finish.

What to send

Form (sheet or rod), size, copolymer or homopolymer, application,
temperature, chemical contact and quantity. Diode Trading EST supplies
POM sheets and rods in Saudi Arabia, and every order ships with a
Material Test Certificate. request a quote

Getting a quotation

Send a short brief with your sizes, quantity, and delivery location
in Saudi Arabia, and we will reply with availability, lead time and a
quotation. If you are unsure of the right grade, describe the working
conditions and we will help you choose.

Tolerances and stress

POM holds close tolerances because it takes up almost no moisture.
But thick POM stock can contain internal stress from manufacture. When
you machine away a lot of material from one side, the part can warp
slightly. For precision parts, rough machine all faces, leave a small
allowance, let the part rest, then finish. Sharp internal corners also
concentrate stress, so add a small radius.

Common mistakes to avoid

using POM in strong acid or strong oxidising environments
using it outdoors for long periods without protection
choosing it for parts that must absorb heavy shock, where nylon is
tougher
trying to bond it with ordinary glue instead of fixing it
mechanically

Questions to ask your
supplier

Is the rod or sheet copolymer or homopolymer? Is it stress-relieved
(annealed)? What is the tolerance on the thickness or diameter? Can I
have a sample offcut to test machining before ordering a large
quantity?

Examples of good POM
applications

A cam follower, a precision guide roller, a pump impeller for
non-aggressive fluids, a spring-clip, a food machinery gear (in suitable
grades) and a valve seat all take advantage of POM’s stiffness, low
friction and stable size. In each case the part is small to medium, runs
at moderate temperature and does not see strong acid.

FAQ

What is POM? Polyoxymethylene, a stiff, low-friction
engineering plastic also called acetal.

Is POM the same as Delrin? Delrin is a brand name of
a POM. The material family is the same.

Does POM absorb water? Very little, which is why it
holds its dimensions.

Can POM be used outdoors? Only with protection, as
UV can degrade it.

Products related to this article

Diode Trading EST supplies these Engineering Plastics from stock in Dammam, with delivery across Saudi Arabia and the GCC.

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