Delrin 100AF Plate, PTFE Fiber Filled

Acetal homopolymer with PTFE fiber dispersed through it - the premium bearing and wear plate in the acetal family, and the one specified when a part has to run dry against metal and keep running. The PTFE drops dynamic friction against steel to about 0.19 and transfers to the mating surface, so it lubricates both sides.

Published figures: tensile strength 8,000 psi, flexural modulus 445,000 psi, Rockwell M85 and R115, melting point 347F, continuous service to 180F unloaded, water absorption 0.2 percent at 24 hours and 1 percent at saturation. Specific gravity is 1.50 against the unfilled 1.42, so it weighs about 6 percent more per square foot - worth knowing on a freight quote.

Where it goes: bearings and bushings machined from plate, wear strips and slides, thrust washers, cams and gears running unlubricated, and any sliding part where the alternative is oiling something you cannot get at.

The trade against the unfilled grade is strength for friction: 8,000 psi tensile against about 10,000, and it is softer at M85 against M94. If the part is structural rather than sliding, the unfilled plate is the better and cheaper answer.

No food-contact claim is made on this grade, and that is not caution for its own sake. The FDA acetal sections clear the resin and a short list of adjuvants; the filler in this grade is not among them. Published compliance charts list the filled acetal grades as not FDA compliant. If you need a food-contact acetal, ask us about the unfilled or a purpose-built food grade and we will tell you what the certificate actually covers.

The warning worth more than any number on this page: CHLORINE ATTACKS ACETAL AT 3 TO 5 PPM. That is ordinary municipal tap water and ordinary sanitizing concentration. Acetal in a chlorinated circuit, a pool system or a sanitized wash-down line will craze and fail, and almost nobody prints this. Strong acids and strong bases attack it too, and the homopolymer's window is the narrower one. If chlorine is anywhere in the application, ask us before you machine it.

Machining notes. It is among the easiest engineering plastics to machine well and takes a genuinely fine finish - sharp tools, positive rake, generous chip clearance, coolant optional on light cuts. Thermal expansion is high for a plastic, so a part machined warm measures differently cold; let heavy sections normalize before the finishing cut. Homopolymer is the harder and more brittle of the two acetals, so inside corners want a radius.

Safety, and this is specific rather than boilerplate. Acetal evolves FORMALDEHYDE above 446F and also on contact with strong acids or strong bases. OSHA's permissible exposure limit is 0.75 ppm over eight hours with a 2 ppm short-term cap, and it is a sensitizer, so repeat exposure matters. Keep tools from overheating the cut, use local exhaust, and never let acetal swarf mix with PVC, because halogenated polymers can trigger sudden formaldehyde release from it. Ask us for the manufacturer's Safety Data Sheet and work to it rather than to this paragraph.

How this is sold: by the square foot, cut to the size you need. The mills supply plate in full sheets and we cut from them, so give us the dimensions and we will quote the cut piece rather than making you buy a whole sheet.