POM (Polyoxymethylene, Delrin): low friction and high wear resistance

POM, also known as acetal or polyacetal, is the plastic for moving parts. It is hard, stiff, and dimensionally stable, with a smooth surface and low friction against steel and against itself. This allows it to run smoothly without lubrication and wear slowly. It absorbs virtually no moisture, which keeps dimensions stable. QDP chooses POM for gears, sliding parts, and hinged components.

Because of the combination of three properties. The coefficient of friction is low, so parts move smoothly over each other without grease. The material is wear-resistant, so that smoothness lasts for years. And it is dimensionally stable because it hardly absorbs moisture, so the tooth shape stays as it was. Few other plastics have all three at once, and certainly not in this price range. QDP therefore uses POM as standard for moving parts.

A lot: approximately 1.8 to 2.5 percent, together with PP and HDPE the highest among common materials. Moreover, it continues to shrink afterward, so the size continues to change for the first days after production. For a gear with a tight fit, this is decisive because the mold must be built to exactly the right final size. That's why you measure at a fixed moment after molding. QDP documents this measurement moment in the quality agreement.

Hardly at all, and that's the price of the smooth surface that makes the material so suitable for moving parts. Glue and paint hardly adhere to it without aggressive pretreatment. In practice, connections are therefore made by snapping, screwing, or clamping, and text is placed in the mold instead of printing on it. QDP incorporates the connection and the marking into the part.

To most, yes. Oils, greases, fuels, alcohols and the usual solvents do not affect it, making it suitable for machine parts and parts in an oil bath. The exceptions are strong acids and prolonged exposure to chlorinated water, which affect the material. For swimming pool and dosing applications, this requires extra attention, especially for long-term contact. QDP checks the usage environment before fixing the material selection.

For the moving interior of products: gears, bearing bushes, sliding blocks, rollers, hinges, spring parts, dosing mechanisms and closures. It is also commonly found in pumps, valves and measuring equipment. Wherever a part must move smoothly and for years without lubrication, this is the starting point. Often it is out of sight in the product, exactly where the movement happens. QDP injection molds POM among others for dosing and moving parts.