Polyoxymethylene (POM)

Polyoxymethylene (POM, also called polyacetal, polyformaldehyde) is a highly molecular thermoplastic material. It is often used as an engineering grade plastic, especially for precision parts, due to its high degree of stiffness, low friction coefficient, as well as dimensional and thermal stability.

Surface energy and contact angle

POM or polyacetal is a thermoplastic with very good sliding properties and a low surface energy of 45,5 mN/m which cannot be bonded well without surface treatment. Only a chemical modification of the surface leads to good adhesion values. Plasma treatment can increase adhesion by a factor of 10.

The chart shows the increase in bond strength of five samples – one set have been simply cleaned, the second set have been plasma treated. They were bonded with a two part methyl methacryate adhesive, although other adhesive chemistries can be tested, including epoxy structural adhesives and cyanoacrylate adhesives.

POM is extremely solid, hard and stiff in a wide temperature range. It maintains its high ductility up to -40 °C (-40 °F) and has excellent abrasion and heat resistance, a low friction coefficient, good electrical, dielectrical and lubricant properties, and permits only minimal water absorption. In many cases, it can replace metal.

POM is processed via injection molding, extrusion, extrusion blow molding or machining.

• Gear wheels, sliding elements, guide elements, housing components, spring elements, chains, screws, nuts, fan wheels, pump parts, valve bodies
• Electrical engineering: insulators, coil bodies, plug connectors
• Vehicle manufacturing: steering column (e. g. levers for lights, indicators), window regulators, door lock systems, sockets
• Furniture making: locks, handles, hinges or curtain rails
• Clothing: zip fasteners