Sheet in POM H 1000x500 mm black

A sheet in POM H is acetal in homopolymer form. The difference from the copolymer version POM C lies in the chain structure: the homopolymer has a more regular molecular order, which makes the material harder, stiffer and somewhat stronger mechanically. In exchange, POM C is somewhat tougher and takes hot water environments better. Both are still acetal and share the same basic profile of low friction, good machinability and excellent dimensional stability. The choice mostly comes down to the load picture and the chemical environment.

The density is 1.42 g/cm³. The material handles continuous duty around 105 degrees and works all the way down to minus 50, which is a considerably wider cold range than many other engineering plastics. Water uptake stays at about 0.85 percent, low enough for a machined part to keep its dimensions even in a damp industrial environment. The flammability rating is HB according to UL 94. For parts that have to work both in a cold outdoor environment and in warm machine rooms the temperature range is a strong property, and POM H is often the choice when a plastic part has to cope with the normal operating environment of the workshop all year round.

Mechanically POM H stands out through a high yield strength and high hardness, combined with still good toughness. The material turns and mills exceptionally well, often with a clearly better surface finish straight from the tool than most other plastics. The chip breaks short, thread cutting works well and small parts can be taken out to tight tolerances. The coefficient of friction is low, wear resistance is good, and the material does not absorb water in any amount that affects the dimensions. Combined with proper oil lubrication, POM H is one of the most proven materials for moving plastic parts in industry, and has been the standard for precision gears for decades.

The sheet format is used a great deal for mechanical components where precision and wear resistance are decisive: gears, racks, bearings, slide bushings, the slide strips of a conveyor track, mechanical parts in pumps and valves, roller holders, cams in packaging machines and the frame in various precision instruments. The electronics and optics industries also use POM H when an insulating, dimensionally and thermally stable component is needed. In the food industry there are food approved versions such as FG; standard POM belongs in more industrial environments. In medical technology the material is used for instrument housings and mechanical parts where repeated sterilization may be involved.

Chemically POM H takes gasoline, oils, greases, alcohol and most aliphatic solvents without trouble. The material is sensitive to strong acids, strong oxidizing agents and strong bases, however. Long term UV exposure outdoors without a stabilizer breaks down the surface. For outdoor use, choose a carbon black pigmented or UV stabilized version. Chlorinated hot water can also cause problems over time; there POM C is the safer choice, since the copolymer structure resists hydrolysis better.

The natural color is white or bone white. We also stock a black version with carbon black. The sheets are cut and milled to drawing and delivered either in raw size or in finished dimensions. The thickness program covers everything from thin panels for shims and spacers up to heavy sheets for milling larger mechanical components. At heavy dimensions and tight tolerance requirements we can also heat treat blanks before final machining to release any internal stress and secure the dimensional accuracy.

The difference between POM H and POM C usually comes down to a trade-off. If you need the highest stiffness and hardness, choose POM H. If the part is exposed to long term hot water, high humidity or a risk of stress corrosion, POM C is the safer choice. For gears and precision parts in a dry industrial environment the choice often lands on POM H. For many constructions POM H is also a natural step down from PA in machining cost and dimensional stability, even if the tensile strength sits a little below a cast PA part. For designers looking for maximum surface finish straight from the lathe, POM H together with POM C are the two materials that consistently give the best result without polishing or post machining, which shows clearly on small precision parts such as sensor housings and optical components. If you are unsure which one suits your application, just get in touch and we will go through the requirements together.

Black 1000x500 mm in homopolymer, hard and stiff, for sliding parts where marks are not to show.