Both materials are sold under trademarked names that are used interchangeably with their generic designations. Getting this right on drawings and purchase orders prevents confusion. [1][2]
| Trade Name | Generic Name | Chemical Family | Trademark Owner | Key Detectable Grade |
|---|---|---|---|---|
| TIVAR® | UHMW PE (Ultra-High Molecular Weight Polyethylene) | Polyethylene | Mitsubishi Chemical Advanced Materials (formerly Quadrant EPP) | TIVAR® VMX (visual + metal + x-ray) |
| Delrin® | Acetal homopolymer (POM-H / Polyoxymethylene) | Polyoxymethylene (POM) | DuPont (now manufactured by Celanese) | Delrin® FG500MXD (metal + x-ray) |
For engineers coming from metals: both of these materials are dramatically weaker and softer than even 6061-T6 aluminum (45 ksi tensile). They are specified not for structural strength but for low friction, wear resistance, chemical inertness, FDA compliance, light weight, and noise reduction. Think of them as wear components and guide surfaces, not load-bearing structure. [1][2]
If you're used to specifying 6061-T6 aluminum, these numbers may look shockingly low. That's normal. Engineering plastics are not metal replacements for structural load. They replace metal where friction, weight, corrosion, noise, or FDA compliance are the governing requirements.
Toggle between properties to compare UHMW PE, Delrin, and 6061-T6 aluminum as a metal reference point. [1][2][3]
UHMW PE (ultra-high molecular weight polyethylene) is defined as polyethylene with a molecular weight of 3.1 million or higher. It has the highest impact strength of any thermoplastic; in standard notched Izod tests, specimens often do not break. It is self-lubricating, non-toxic, and has essentially zero moisture absorption. Its coefficient of friction (0.10–0.22 against steel) is among the lowest of any solid material, comparable to PTFE (Teflon®) but with dramatically better abrasion resistance. [1]
The trade-off: UHMW is soft and spongy compared to Delrin. It has poor dimensional stability (high coefficient of thermal expansion), does not machine as cleanly (it tends to produce stringy chips rather than crisp ones), and cannot hold tight tolerances as well. It also has a lower maximum service temperature (180°F vs 250°F for Delrin). It does, however, float in water (density 0.93 g/cm³), which matters in certain marine and water treatment applications.
Delrin is an acetal homopolymer (POM-H) that behaves more like a metal than a typical plastic. It has high stiffness, excellent dimensional stability, low moisture absorption, and machines with crisp, clean chips similar to free-machining brass. Its surface finish out of the machine is smooth and consistent, which is why it is the preferred material for precision gears, bearings, bushings, valve seats, and any component where tight tolerances and smooth sliding surfaces are critical. [2]
Delrin's coefficient of friction (0.20–0.35) is slightly higher than UHMW's, but its surface is harder and more dimensionally stable, so it produces a smoother, more predictable sliding interface in precision mechanisms. Its higher stiffness means parts don't flex or deform under load the way UHMW does. It also handles higher temperatures (continuous service to 250°F / 121°C vs 180°F / 82°C for UHMW).
In food processing and pharmaceutical manufacturing, broken plastic components can contaminate the product stream. Industry quality systems require that any plastic component in the processing zone be detectable by the inline inspection equipment (metal detectors and/or x-ray systems) installed on the production line. [4]
| Property | TIVAR® VMX (UHMW) | Delrin® FG500MXD (POM-H) |
|---|---|---|
| Detection methods |
Visual (blue + metal detector + x-ray
|
Metal detector + x-ray
|
| Color |
Blue (Visually distinct)
|
Blue (Food industry standard)
|
| FDA compliant? |
Yes - 21 CFR §177.1520
|
Yes - 21 CFR §177.2480
|
| EU 10/2011 compliant? |
Yes
|
Yes
|
| 3-A Dairy approved? |
Yes (Natural)
|
Check spesific grade
|
| Impact resistance |
Excellent (No break)
|
Good
|
| Machinability |
Fair (Stringy)
|
Excellent (Crisp)
|
| Best for |
Wear surfaces, Liners, scrapers, guides
|
Gears, bushings, rollers, valve seats
|
All values for standard virgin grades at room temperature.6061-T6 aluminum included as a metal reference point.[1][2][3]
| Property | UHMW PE | Delrin (POM-H) | 6061-T6 (ref) |
|---|---|---|---|
| Tensile strength |
5,800 psi
40 MPa
|
10,000 psi
69 MPa
|
45,000 psi
310 MPa
|
| Yield strength |
3,100 psi
21 MPa
|
10,000 psi
69 MPa
|
40,000 psi
276 MPa
|
| Elongation at break | 350% | 25–75% | 12% |
| Flexural modulus |
110,000 psi
760 MPa
|
420,000 psi
2,900 MPa
|
10,000,000 psi
69,000 MPa
|
| Coefficient of friction (vs steel) | 0.10 – 0.22 | 0.20 – 0.35 | 0.47 (dry) |
| Hardness | Shore D 62–66 | Rockwell M80 / Shore D 83 | Brinell 95 |
| Impact strength (Izod, notched) | No break | 1.3 ft·lb/in | N/A (ductile metal) |
| Density | 0.93 g/cm³ (floats) | 1.41 g/cm³ | 2.70 g/cm³ |
| Water absorption (24 hr) | <0.01% | 0.20% | 0% |
| Max continuous service temp. | 180°F / 82°C | 250°F / 121°C | 350°F / 177°C |
| CTE (linear) |
110 µin/in·°F
(very high)
|
47 µin/in·°F | 13.1 µin/in·°F |
| FDA compliant (virgin)? | Yes | Yes (select grades) | N/A |
| Creep resistance | Poor — deforms under sustained load | Excellent | Excellent |
| Machinability | Fair — stringy, spongy | Excellent — crisp chips | Excellent |
| Relative material cost | $ | $$ | $$ |
Our team at C&W machines both UHMW PE and Delrin regularly for food processing, packaging, and conveyance OEMs. We stock common grades including FDA-compliant and detectable versions, and can advise on material selection for your specific application.
