Polyoxymethylene ( POM) is a crystalline polymer
consisting of chains
of a repeating methylene group and oxygen atom (this block is in fact called oxymethylene), forming a plastic material that is highly resistant and relatively inexpensive.
It is also known under the trade names of Zellamid 900, Delrin, Tecaform, Kepital, KEMATAL, Ertacetal and Berlin.
The acetal resins (name of the finished product formed by polyoxymethylenes) are ideal substitutes for precision metal parts (watch gears), levers, bearings, screws
, pipe fittings, hinges
, diving equipment, parts of valves for dispensing hot and cold water, and components for the automotive, telecommunications and transport sectors.
The use of these resins has its advantages and disadvantages:
Advantages: When not reinforced, and in particular in the case of homopolymers, they become extremely rigid plastics. They also possess good mechanical resistance and hardness, and good dimensional stability as they absorb little moisture.
Disadvantages: The main limitation is the ease of combustion with the production of toxic fumes. Non-stabilised products are also attacked by UV rays.