When you're designing a gear assembly — especially one where multiple gears mate together and need to run quietly over a long service life — the material choice is critical. Get it wrong and you get noise, premature wear, dimensional drift, or all three.
POM (polyoxymethylene, also known as acetal or Delrin) is one of the most commonly specified materials for precision plastic gears. Here's why.
Low friction without lubrication
POM has relatively low friction compared with many general-purpose plastics. In a well-designed gear mesh, that can support smoother motion and lower wear. Whether lubrication is still needed depends on load, speed, temperature, mating material, and service-life targets.
Dimensional stability
Gears need to hold their geometry. If a tooth deforms even slightly under load, the mesh gets sloppy, noise increases, and wear accelerates.
POM generally absorbs less moisture than many nylon grades, which can make its dimensions easier to control in changing humidity. A molded gear still needs correct material conditioning, tool design, shrinkage allowance, and process control.
Wear resistance
In gear-on-gear applications, the material takes a beating. POM is often chosen over general-purpose plastics because its wear behavior suits sliding and gear contact. The actual life advantage must be tested in the real assembly; load, tooth geometry, speed, lubrication, and the mating gear can change the result.
Quiet operation
This is where POM can help in products used near people. A well-designed POM gear mesh can run quietly compared with harder material pairings. In robotic arms, height-adjustable desks, and medical beds, that quietness is a functional requirement, not just a nice-to-have.
When POM is NOT the right choice
POM isn't universal. It's not great for:
- Temperatures beyond the selected grade's continuous-use range. Higher-temperature polymers or metal may be a better fit.
- Extreme impact loads. Polycarbonate or nylon might absorb shock better.
- UV exposure without stabilizers. Untreated POM degrades in sunlight.
A real example
We've produced POM gears across multiple specs for use in robotic arms, robots, height-adjustable desks, and automatic medical beds. The combination of complex geometry (multiple tooth profiles in one mold), multi-gear mating precision, and the requirement for silent, wear-resistant operation is exactly what POM is built for.
The takeaway: when an application needs precise mating, quiet operation, and controlled wear, POM is worth evaluating early — then validating in the real load case before production.
Next step
Turning an idea into a shipped product?
Send a drawing, sketch, or sample. A real engineer reviews it — usually within a business day, no commitment.