Acetal resins (polyoxymethylene or POM) are engineering thermoplastics based on formaldehyde polymerization technology. These highly crystalline resins are strong, rigid and have a low coefficient of friction against metals, acetals and other plastics. They are creep resistant so they are good for parts where dimensional stability is important.
Acetal resins have high tensile strength, stiffness, resilience, fatigue endurance and moderate toughness. Acetals have high resistance to organic solvents, excellent dimensional stability, a low coefficient of friction and outstanding abrasion resistance among thermoplastics.
Acetals’ resistance to creep is excellent. Moisture, lubricants and solvents including gasoline and gasohol have little effect on this property, which is important in parts incorporating self-threading screws or interference fits.
Good electrical properties qualify these materials for electrical applications requiring long-term stability. Acetal copolymers retain much of their toughness through a broad temperature range and are among the most creepresistant of the crystalline thermoplastics. A low moistureabsorption characteristic permits molded parts to serve reliably in environments involving humidity variations.