Acetal polymers, referred to chemically as PolyOxyMethylene, are semi-crystalline engineering themoplastics made by the polymerization of formaldehyde. They have physical properties that are not available with metals or most other plastics; high mechanical strength and rigidity, low coefficients of friction, low moisture absorption, excellent dimensional stability, fatigue endurance, and resistance to abrasion and creep. These materials are also resistant to a wide range of solvents and have good electrical properties.