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Engineering Plastic

POM / Delrin

POM (acetal), best known as Delrin, is a semi-crystalline engineering plastic prized for dimensional stability, stiffness, and a naturally low-friction surface. At 1.41 g/cm3 with 70 MPa tensile strength and R120 hardness, it machines like a soft metal and holds tight tolerances, making it the default choice for precision low-friction parts.

How POM / Delrin machines

Among the most machinable plastics at 4.5/5, POM cuts cleanly with sharp tools, leaves crisp threads and chips freely without gumming. It is dimensionally stable, so parts hold tolerance after machining. Watch frictional heat on deep cuts; acetal softens near its 90 C limit and can outgas formaldehyde if overheated, so keep tools sharp and feeds steady.

Manufacturing & processing

POM is processed by CNC machining from rod and plate, or injection molded for volume parts. It does not glue or solvent-weld well, so design for mechanical fastening, snap-fits, or press-fit assembly. It is not suited to bonding-dependent joints; threaded inserts and self-tapping screws work reliably.

Typical applications

POM excels at precision gears, bearings, bushings, cams, rollers, valve components, and small mechanical parts where low friction and wear resistance matter. Its stiffness and stability suit insulators, manifolds, and snap-together housings. Common in automotive, conveyor, and consumer-mechanism parts that must run dry without lubrication.

When to choose it

Choose POM when you need a stiff, dimensionally stable plastic that machines to tight tolerances and slides with low friction unlubricated. Pick nylon instead for higher impact and toughness, or PEEK when temperatures exceed 90 C. Avoid POM where strong solvent bonding or service above its temperature limit is required.

Suitable surface finishes

Common finishes for POM / Delrin: bead blasting, powder coating. Use the finish selector →

FAQ

Is Delrin the same as POM acetal?
Delrin is DuPont's brand of POM homopolymer. Generic acetal includes both homopolymer and copolymer grades. They share the same 1.41 g/cm3 density, low friction, and excellent machinability; homopolymer is slightly stiffer and stronger, while copolymer resists centerline porosity and hot-water exposure better.
Why does machined Delrin smell during cutting?
Overheating acetal can release formaldehyde, producing a sharp odor. It signals that frictional heat is near the 90 C service limit. Keep tools sharp, use steady feeds, and provide chip clearance or air blast to keep cutting temperature down and avoid degrading the surface.
Can POM parts be glued together?
Not reliably. POM's low-friction, chemically inert surface resists most adhesives and does not solvent-weld. Design for mechanical assembly instead, using screws, threaded inserts, snap-fits, or press fits. If bonding is unavoidable, surface treatment is required and joint strength stays limited.

Property values are typical/nominal for early guidance and vary by temper, grade, supplier and heat treatment. Confirm critical specs against a certified datasheet or with an mfgiq engineer.