Acetal (polyoxymethylene) is a semi-crystalline thermoplastic that is available in both copolymer and homopolymer grades (Delrin®), in addition to several filled Delrin® grades. Acetal is easy to machine and offers good dimensional stability, high strength, and stiffness.
As a semi-crystalline material, Acetal is also characterized by a low coefficient of friction and good wear properties-especially in wet environments.
Because Acetal absorbs minimal amounts of moisture, its physical properties remain constant in a variety of environments. Low moisture absorption results in excellent dimensional stability for close-tolerance machined parts. In high moisture or submerged application, Acetal bearings outperform nylon 4 to 1. Acetal is ideally suited for close tolerance mechanical parts and electrical insulators which require strength and stiffness. It also offers resistance to a wide range of chemicals including many solvents.
PMI machines both homopolymer and copolymer grades of Acetal including enhanced bearing grade materials. Acetron® GP POM-C Acetal is porosity-free and is an excellent choice for general purpose grade. For slightly higher mechanical properties we offer and machine the homopolymer Acetal products. For improved frictional properties, PTFE-enhanced Acetron® AF products are offered.
Notable Material Features
- High mechanical strength, dimensional stability, and rigidity
- Very low moisture absorption
- Good wear and abrasion resistance
- Wide range of chemical resistance (including hydrocarbons, neutral chemicals, and many solvents)
- Natural lubricity
Grades Of Acetal
Acetal Copolymer (unfilled)
The copolymer grade offers excellent performance at a slightly lower cost than Delrin®. Acetal copolymer may exhibit center line porosity, but porosity-free material is available. Certain grades are FDA, USDA, NSF, Canada AG and 3-A Dairy compliant. Low stress levels and high strength assure flatness and dimensional stability up to a maximum continuous service temperature of 180°F.