POM-C vs POM-H: Copolymer or Homopolymer — Which Acetal Should You Choose?

Where POM-C Wins

· Repeated exposure to hot water, weak alkalis, or cleaning agents

· Large-diameter rod and thick sections where centre porosity is a risk

· Parts with complex geometry where the wider processing window helps

· Food and medical applications where the copolymer grades dominate

· Any duty where hydrolytic stability outweighs peak strength

Matching Material to Duty

In day-to-day practice the differences are modest, and most applications are served perfectly well by either grade. The exceptions matter, though: a POM-H bushing running in a hot detergent wash line can develop surface cracks within months, while a POM-C gear under high fatigue load will wear faster than the homopolymer equivalent. If your part sees sustained heat with moisture or cleaning chemistry, choose the copolymer. If it sees dry, high-cycle mechanical load, choose the homopolymer. When in doubt, tell us the duty cycle and cleaning regime — the answer usually becomes obvious. NAGOMER stocks both chemistries in sheet and rod and machines finished parts to drawing.

One last practical note: both acetal grades take up a little moisture and should be stored in a dry, ventilated area away from direct sunlight. Machined parts benefit from annealing at around 140–150°C for a period matched to wall thickness, which relieves internal stress and markedly reduces the risk of cracking in service. It is a cheap step that prevents an expensive failure.

Related reading: POM Plastic Sheet Properties, POM Gears Design Guide, and Engineering Plastics for Food & Beverage Processing.