Comparison between HDPE, UHMW and acetal for custom machined technical parts

HDPE, UHMW or acetal (Delrin)?

Three sheets of opaque plastic, often black or white, all three "wear-resistant" according to the catalogs… No wonder we're regularly asked which one to choose. And yet HDPE, UHMW and acetal (Delrin) fill three quite distinct niches.

In a sentence: UHMW slides and endures abrasion, HDPE is the economical workhorse for wet and food environments, and acetal is the precision plastic for mechanical parts. Here's how to tell them apart for real.

HDPE

The all-rounder for wet environments

High-density polyethylene: non-toxic, non-staining, very low moisture absorption. It washes and sanitizes without complaint — hence its top spot in food processing, marine environments and tanks.

  • Thicknesses: 1/8″, 1/4″, 3/8″, 1/2″
  • Colors: black and natural white
  • Melting point: 260 °F

UHMW

The sliding and abrasion specialist

Ultra-high-molecular-weight polyethylene (Tivar equivalent): waxy self-lubricating surface, very low friction, exceptional resistance to sliding wear. It works quietly against metal, even in the cold.

  • Thicknesses: 3/8″ and 1/2″
  • Colors: black and natural white
  • Melting point: 275 °F

Acetal (Delrin)

The rigid precision plastic

Polyoxymethylene (POM, Acetron GP equivalent): the densest and by far the most rigid of the three. Low friction, excellent dimensional stability — it's the material for parts that pivot, mesh or must stay precise.

  • Thicknesses: 1/8″, 3/16″, 1/4″
  • Color: black
  • Melting point: 320 °F

How are these three plastics cut at Laseo?

Good news: no need to choose a process, all three go through CNC routing. Unlike acrylic, these polymers are not laser-cut — the CNC bit gives smooth edges and excellent precision, with small holding tabs that come off with a light deburring.

MaterialCutting tolerancePart size (min – max)
HDPE±0.005″1.000″ × 2.000″ – 35.000″ × 47.000″
UHMW±0.005″1.000″ × 2.000″ – 35.000″ × 47.000″
Acetal±0.009″1.000″ × 2.000″ – 35.000″ × 47.000″

All three also accept tapping (M4 up to 1/2-20 UNF depending on thickness) and hole countersinking — handy for screwing directly into the part without added hardware.

The numbers that set them apart

A glance at the elastic modulus is enough to understand why these three materials aren't interchangeable: acetal is about 5 times more rigid than UHMW.

Property HDPE UHMW Acetal (Delrin)
Density59.9 lb/ft³58.0 lb/ft³86.4 lb/ft³
Elastic modulus≈174 ksi≈80 ksi≈380–490 ksi
Tensile strengthn/a6 ksi10 ksi
Elongation at break≈400%≈300%≈25%
Melting point260 °F275 °F320 °F
Thicknesses offered1/8″ to 1/2″3/8″, 1/2″1/8″, 3/16″, 1/4″
StrengthHygiene, wet environmentsSliding, abrasion, impactsRigidity, precision

Values taken from our data sheets — the detail by thickness is on the HDPE, UHMW and acetal sheets.

Which material for which project?

Your projectOur verdict
Conveyor wear strips and guides, slide railsUHMW — self-lubricating, it slides silently against metal and lasts a long time
Snow-dump box, chute or hopper linerUHMW — abrasion and the Canadian cold don't faze it
Food-processing board or surfaceHDPE — non-toxic, non-staining, washes and sanitizes easily
Tank walls, marine or car-wash partsHDPE — very low moisture absorption, insensitive to common cleaners
Gears, bushings, pulleys, mechanical slidesAcetal — rigid and low-friction, it holds precise fits
Shop jigs and fixtures that must not "move"Acetal — its dimensional stability is the best of the three

The classic trap

Grabbing HDPE "because it's the same" for a tight-fitting mechanical part: with a modulus roughly 2 to 3 times lower than acetal, the part flexes and slop sets in. Conversely, using acetal in a pure abrasive sliding application means paying for rigidity you don't need — UHMW will survive it better. When in doubt, send us your drawing: the instant quote lets you compare all three materials in a few clicks.

Need a transparent part instead?

If your project calls for transparency — display case, machine guard, protective screen — the match is instead between acrylic and polycarbonate. We compare them in detail in our guide Acrylic or polycarbonate?

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