What is POM (Polyoxymethylene)? Properties, Types, and Applications

What is POM?

POM (Polyoxymethylene), also known as acetal resin or polyacetal, is a high-performance engineering plastic. Compared with general-purpose plastics, POM provides superior heat resistance and mechanical strength, making it suitable for a wide range of industrial applications.

POM is a crystalline thermoplastic resin made up primarily of repeating (-CH2O-) units. There are two main types: which is formed from molecular chains of polyoxymethylene linked by formaldehyde, and copolymer, which is made by combining trioxane (a formaldehyde trimer) with ethylene oxide or other monomers.

Well-known examples include DuPont’s Delrin® for homopolymer and Polyplastics’ Duracon® for copolymer.

Homopolymer (e.g., DuPont’s Delrin®)

• Formed entirely from identical monomer units.

• Its main chain is formed solely from carbon-oxygen bonds.

• Offers slightly higher crystallinity, strength, and rigidity.

Copolymer (e.g., Polyplastics’ Duracon®)

• A copolymer is a polymer made from different types of monomer units, most commonly two types.

• Exhibits better thermal stability and less degradation during molding.

• Lower crystallinity than homopolymers, resulting in improved flexibility but slightly reduced strength.

• Melting point and heat deflection temperature are about 10 °C lower than homopolymers, but practical heat resistance is largely equivalent.

Key Properties

• High mechanical strength, wear resistance, and chemical resistance

• Naturally self-lubricating with a low coefficient of friction, ideal for sliding parts

• Continuous service temperature for homopolymers: 85 °C

• Continuous service temperature for copolymers: 105 °C (can withstand short-term exposure up to approximately 150 °C)

• Excellent dimensional stability (low moisture absorption)

• Easy to machine with minimal burr formation (even if burrs form they are easy to remove)

• Makes POM ideal for precision parts, including components with small holes

Considerations When Choosing POM

• Not suitable for strong acids (e.g., hydrochloric acid, sulfuric acid).

• Poor bonding properties: adhesives are generally ineffective.

• Low weather resistance: prolonged outdoor use may cause discoloration or degradation.

• Flammability: burns with a blue flame and formaldehyde odor, making it unsuitable for use near open flames.

Typical Applications

• Automotive parts (e.g., fuel pump components)

• Bearings and sliding components

• Gears, pulleys, and switches

• Precision machine parts

• Consumer goods and everyday items

Available Colors & Sizes

Stock Colors

• Standard colors: White, Black, Yellow

Stock Sizes

• Round rods: φ4–φ250 mm

• Sheets/plates: Thickness from 0.2 mm up to 100 mm

Major Brands and Manufacturers

Development & Market Adoption

POM was first developed by DuPont in the early 1950s, with production beginning in 1960 under the trade name Delrin®. Soon after, other companies like Celanese (now Ticona) and Polyplastics introduced their own versions (e.g., Duracon®).

By the 1960s, POM’s high wear resistance made it a popular choice for bearings. Over time, its strength, self-lubricating properties, and affordability expanded its use into:

• Gears, screws, and fasteners

• Musical instruments (flutes, whistles)

• Electronics housings and modules

• Automotive components

Today, POM is a standard engineering plastic for applications requiring durability, strength, and precision.

Step Up Your Project with Yumoto Electric

Yumoto Electric delivers high-quality components fast, worldwide. We provide precision machining for a wide range of engineering plastics, including PEEK, PPS, MC Nylon, and POM.

If you’re unsure about material selection or machining methods, we offer complimentary consultations to help optimize your design and production. For any questions, please feel free to contact us.