Differences Between Acetal and UHMW Acetal (polyoxymethylene or POM) is a high strength, low friction engineering plastic that has excellent wear properties in both wet and dry environments. Acetal is chemically resistant to hydrocarbons, solvents, and neutral chemicals. Easy to machine, acetal makes an outstanding choice for applications that require complex, tight tolerances. UHMW (ultra high molecular weight polyethylene) is an extremely tough plastic with high abrasion and wear resistance. The versatility of polyethylene has made it a popular plastic for countless industrial applications that require durability, low friction, and chemical resistance. Applications include wear strips, chain guides, packaging machinery parts, and marine dock fender pads. Acetal Material Characteristics Easy to machine Good chemical resistance Strong and stiff Easy to fabricate Good for friction and wear Good electrical insulation Sealing Prototyping Good for bearings Acetal Applications: Bearings and bushings Pump and valve parts Manifolds Gears Jigs and fixtures Food processing and other packaging machinery parts Wear pads Electrical components Acetal Common Brands Delrin®, SUSTARIN®, TECAFORM® UHMW Material Characteristics Good chemical resistance Impact resistant Easy to fabricate Good for friction and wear Good for bearings Easy to machine UHMW Applications: Chute, hopper, and truck bed liners Wear strips and guide rails Star wheels and idler sprockets High speed conveyors Packaging machinery parts Food processing machinery parts Bumpers, pile guards, and dock fenders UHMW Common Brands Polystone® M, GUR®, Tivar® Typical properties of ACETAL and UHMW UNITS ASTM TEST HOMOPOLYMER ACETAL COPOLYMER ACETAL UHMW-PE Tensile strength psi D638 10,000 9,800 3,100 Flexural modulus psi D790 420,000 370,000 110,000 Izod impact (notched) ft-lbs/in of notch D256 1.5 1.0 18.0* Heat deflection temperature @ 264 psi °F D648 257 230 - Maximum continuous service temperature in air °F 185 195 180 Water absorption (immersion 24 hours) % D570 0.25 0.20 slight Coefficient of linear thermal expansion in/in/ °Fx10-5 D696 6.8 6.1 11.1 Coefficient of friction (dynamic) 0.20 0.21 0.10 - 0.20 Values may vary according to brand name. Please ask your Curbell Plastics representative for more specific information about an individual brand. * Double-15° notch