Polyacetal - POM (PolyOxyMethylene) is a high crystalline thermoplastic with a high level of stability and rigidity as well as good sliding properties and wear resistance with a low level of moisture absorption. Its good dimensional stability, exceptional fatigue resistance and excellent machining properties make Polyacetal a versatile design material also for complex components. It satisfies high surface finish requirements and offer better surface hardness, toughness and excellent solvent and gasoline resistance.
A High Degree of crystallinity makes acetals stiffer and stronger than most thermoplastics, yet they are tough at ambient and low temperature, good dimensional stability is a key property.
Acetals absorb little water, minimizing its effect on their physical properties.
There are two basic types of acetal resins; Homo-polymer and Copolymer.
The homo-polymersâ€™ strength properties tend to be slightly higher than those of the copolymers. Delrin is a homo-polymer Polyacetal. Delrin has higher (short term) heat deflection temperatures than copolymers, but their continuous useÂ temperature is 85Â°C (185Â°F) compared to 100Â°C (212Â°F) for copolymers. The homo-polymers tend to have somewhat greater surface hardness, higher degree of density and a slightly lower coefficient of friction.
The copolymers, compared to homo-polymers, tend to absorb less water, are more resistant to hydrolysis and have superior processing characteristics. Copolymers, however, have higher impact toughness, greater wear resistance and thermal / chemical resistance.
Acetals are mostly used in applications where excellent surface finish & accuracy with good dimensional stability are required. These are also preferred as a good material for food & pharmaceutical, chemical & oil industries.