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.
| Material | Cutting tolerance | Part 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) |
|---|---|---|---|
| Density | 59.9 lb/ft³ | 58.0 lb/ft³ | 86.4 lb/ft³ |
| Elastic modulus | ≈174 ksi | ≈80 ksi | ≈380–490 ksi |
| Tensile strength | n/a | 6 ksi | 10 ksi |
| Elongation at break | ≈400% | ≈300% | ≈25% |
| Melting point | 260 °F | 275 °F | 320 °F |
| Thicknesses offered | 1/8″ to 1/2″ | 3/8″, 1/2″ | 1/8″, 3/16″, 1/4″ |
| Strength | Hygiene, wet environments | Sliding, abrasion, impacts | Rigidity, 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 project | Our verdict |
|---|---|
| Conveyor wear strips and guides, slide rails | UHMW — self-lubricating, it slides silently against metal and lasts a long time |
| Snow-dump box, chute or hopper liner | UHMW — abrasion and the Canadian cold don't faze it |
| Food-processing board or surface | HDPE — non-toxic, non-staining, washes and sanitizes easily |
| Tank walls, marine or car-wash parts | HDPE — very low moisture absorption, insensitive to common cleaners |
| Gears, bushings, pulleys, mechanical slides | Acetal — 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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