Sheet in POM LF 1000x500 mm black

Sheet in POM LF is an acetal plastic modified with a built-in solid lubricant. The abbreviation LF stands for low friction and refers to the material being internally lubricated straight from the factory. The additive lowers the coefficient of friction against steel and other plastics, and improves wear resistance in applications where the part has to slide dry or with only occasional lubrication. That means a sliding component can be designed entirely without external lubricant, which is valuable in clean rooms, food environments and in equipment where oil must not come into contact with the product.

The density is 1.45 g/cm³ and the continuous service temperature reaches up to 100 degrees. The lowest working temperature is about -20 degrees. Water absorption stops around 0.7 percent, lower than for standard POM, which keeps dimensional stability good even in a damp environment. The fire rating is HB according to UL 94. The low water absorption is one of the reasons the sheets hold their tolerances even with temperature swings and humid air in unlimited operation.

POM LF differs from PTFE-filled POM on one important point. Here the lubrication is mixed straight into the polymer as an internal lubricant in compound form, which gives a more even friction behavior over time and often somewhat better wear resistance at slightly higher load. It is made to combine the stiffness and dimensional stability of POM with a sliding surface that needs no ongoing maintenance. The PV value in dry running is higher than for standard POM, and the friction behavior is stable over a long service life without the lubricating effect fading.

In sheet form the material goes straight into milling of slide plates, guide rails, wear surfaces, slide strips and wear washers in packaging machines, conveyors, assembly equipment and food production. POM LF is also often used as a slide block in hydraulic cylinders, as a wear coating in cams and guide elements, and as a sliding surface in assembly fixtures where moving parts have to work quietly and cleanly. In the textile and paper industry the material is common as a guide rail for belts and straps; quiet running is a bonus in environments where noise from conveyors would otherwise become a work environment problem.

Machining follows the POM tradition. The material is milled, turned, drilled and cut with standard tools for plastic or brass. The chips are short and clean, the surface comes out glossy and dimensionally safe, and thermal linear expansion is around 0.11 mm per meter and degree. Keep that in mind for press fits against steel or aluminum, especially if the operating temperature varies. Use sharp tools with a positive rake angle; dull edges heat the material and spoil the sliding surface on the finished component.

POM LF glues badly and is not practical to weld; parts are mounted with screws, clamps or a mechanical fitting. To make use of the low friction the sliding surface does not need to be thick. A thin sheet can be used as a screwed-on wear surface against steel, or as a complete component where the bearing and load-carrying functions are combined. That opens up design solutions where only the wearing zone is POM LF while the rest of the part is metal or another plastic.

Chemically the material handles most organic solvents, mineral oils, fuels, weak acids and alcohol. Strong acids, concentrated bases and oxidizing agents such as chlorine solutions should be avoided in longer contact. The natural color can be gray or blackish depending on the character of the additive, and the material is not UV stable for long outdoor exposure. When you choose a mating surface, hardened or ground steel works best; soft metal wears the sliding surface down faster.

Choosing between POM LF and POM H+PTFE is often a small-scale difference and is governed by the load picture of the part. POM H+PTFE gives very low friction at light loads and low surface speed. POM LF tends to take slightly higher PV values and longer dry running without losing the wearing surface. For slide plates with constant movement and moderate load, POM LF is often a reliable choice. In the same way POM LF is particularly suitable where one and the same part combines a load-carrying and a sliding function, since the stiffness and strength of the material are not sacrificed for the sliding property.

Black sheet 1000x500 mm in electrically conductive acetal, for parts that have to lead static charge away.

The sheets are supplied in standard thicknesses and format sizes, cut to order, and in larger volumes they can also be pre-cut into finished blanks. When choosing the right POM grade it is always the actual operating environment of the part that decides; a sliding surface in food production makes different demands than a wear strip in a punching machine. If you are unsure which grade matches your application, get in touch with a sketch or a description of the function and we will come back with a proposal for grade and dimension that suits your design.