Round Rod in POM LF Nano 1000 mm black

A round rod in POM LF Nano is acetal with friction modification, meant for turned parts that have to slide against steel without lubrication. LF stands for low friction; the additive is nanoscale and is worked into the polymer during manufacture, so the sliding properties run through the whole cross section of the rod and not only in the surface. The grade complements standard POM where the demands on dry sliding surfaces are higher than unfilled acetal can handle.

The base is POM, the same material as our ordinary acetal rod, with everything that follows from it: high stiffness, low moisture absorption, fine dimensional stability and a machinability that has made POM the standard choice in automatic lathes. The density of POM is around 1.41 g/cm³, which gives steady, vibration damped parts.

The dimensional stability is worth underlining. Where nylon grows by a few tenths of a percent in a humid environment, POM stays put, and that is often the whole reason POM is chosen for bushings and guide sleeves with tight fits. A part turned to size in January still holds the size in August, in particular in premises without climate control.

The difference against standard POM sits in the friction. Unfilled POM already slides well against steel, but in continuous dry running, at higher surface speeds or where jerky motion disturbs the process, a friction modified grade takes over. Think of conveyor screws that run around the clock, or actuators that creep slowly under load; those are the operating cases that motivate a modified grade. Exact friction and wear values are given in the manufacturer's data sheet.

Slip-stick deserves an explanation. When the static friction is clearly higher than the dynamic one, the movement jerks into motion instead of sliding smoothly, which is heard as squealing and felt as juddering in slow movements. Friction modified grades even out the difference between the two, and it is in exactly those slow, heavy movements that they do the most good. The phenomenon rarely disappears with more grease; the material choice is the durable solution.

The nano additive separates the grade from older solutions. Oil filled and PTFE filled acetal grades have been around for a long time and they work, but coarser fillers leave their mark on strength and surface finish; a nanoscale modification is, according to the grade description, the manufacturer's way of reaching the sliding properties with less effect on the base material. In the lathe the rod behaves like ordinary POM.

Typical parts are bushings and plain bearings in conveyors and packaging machines, guide sleeves, rollers, gears with a small module, slide elements and spacers under movement. In short the same family of parts as for ordinary POM, but in the situations where the bearing has to run dry for a long time. Rollers and running wheels in lighter door systems are another area where quiet, dry motion is appreciated.

Dry running also places demands on the mating surface. A ground steel surface with an even finish gives the lowest friction and the least wear; the rule of thumb we usually start from is a surface roughness around Ra 0.2 to 0.8 for plain bearings in plastic.

The turning is just as productive as for standard acetal. The surface comes out bright straight from the machine, the chip is dry and easy to handle, and standard tools in HSS or carbide are plenty. Avoid overheating at high spindle speeds; POM melts around 165 °C and the chip should be dry, not smeary. Gluing is, just as for all POM, not a good idea, so choose a mechanical fastener or threaded inserts.

The rod is supplied in meter lengths.

Wondering about diameter, PV value or the choice between POM grades? Give us a call, we will help you work the numbers on the choice.