Polyoxymethylene
Polyoxymethylene (POM) is commonly known as acetal. It is a widely used semi-crystalline engineering polymer because of its excellent balance of rigidity, toughness and dimensional stability.
There are two basic types of polyacetal available.
Acetal Homopolymer – manufactured by Dupont with the trade name Delrin acetal resin – has higher mechanical strength, stiffness, hardness and creep resistance as well as a lower thermal expansion rate and often it also presents a better wear resistance than the acetal copolymer grade.
Acetal Copolymer
Acetal copolymer is more resistant against hydrolysis, strong alkalis and thermal-oxidative degradation than the acetal homopolymer
Polyacetal, POM, has valuable properties, which include:
• High stiffness, strength and hardness
• Excellent impact strength down to minus 40 degrees C
• Excellent fatigue strength
• Low moisture absorption
• Outstanding tribological properties
• Superior chemical resistance to solvents
• Easy processing
• High mould shrinkage
By nature of its chemical composition, polyacetals are not available as Flame retardant grades. They burn readily with an almost invisible flame and noxious gas.
Polyacetal, POM has the lowest wear of all thermoplastics at room temperature. This coupled with excellent dimensional stability when moulded make acetals the natural choice for cams, slides, gears and bearings. Filled grades with PTFE, silicon oil and aramid fibre can be used to further enhance wear and friction properties.
Polyacetal, POM, is not UV resistant and outdoor applications must be stabilised, normally with active carbon black.
Typical applications for Polyacetal include:
• Friction bearings
• Gears
• Spring elements
• Housing parts
• Rollers
• Friction strips
• Plugs
• Insulators
• Snap fit connectors
• Seals
Polyacetal, POM, can easily be processed by Injection Moulding, and ProPlastix can advise on all your specific applications.
