POM-H vs. POM-C — What's the Difference?

POM-H (Polyoxymethylene Homopolymer) and POM-C (Polyoxymethylene Copolymer) are two types of polyacetal, a thermoplastic used in precision parts requiring high stiffness, low friction, and excellent dimensional stability. POM-H is characterized by its high mechanical strength, rigidity, and resilience at temperatures below its melting point. It is suitable for applications where strength is a critical factor, including gears, bearings, and structural components in machinery. POM-H's homopolymer structure contributes to its superior physical properties but makes it slightly less resistant to hot water and chemicals compared to POM-C.

POM-C, on the other hand, incorporates comonomer units in its polymer chain, enhancing its thermal stability and resistance to chemicals. This makes POM-C more suitable for applications involving high temperatures or exposure to harsh chemical environments. While it maintains many of the beneficial properties of POM-H, including low friction and good wear resistance, POM-C's mechanical strength and rigidity are slightly lower. Its enhanced chemical resistance makes it preferred for parts used in chemical processing, hot water applications, and where lower formaldehyde emissions are required.

The choice between POM-H and POM-C depends on the specific requirements of the application. POM-H's higher strength and rigidity make it ideal for mechanically stressed parts, while POM-C's better chemical resistance and thermal stability suit environments where these factors are more critical. Both types of POM offer excellent machinability and are widely used in the automotive, electrical, and consumer goods industries for a variety of components.

Manufacturers often select POM-H for its performance in precision applications where dimensional stability over a wide range of temperatures is necessary. Conversely, POM-C is chosen for components that may experience chemical exposure or need to operate in higher temperature ranges. Both materials are recognized for their durability and longevity in challenging environments.

In essence, while POM-H and POM-C share many properties characteristic of polyacetal plastics, including high strength, low friction, and excellent machinability, their differences in chemical composition lead to distinct advantages in mechanical strength for POM-H and in thermal and chemical resistance for POM-C. These distinctions guide engineers and designers in selecting the appropriate material based on the operational demands of the final product.