UHMW Polyethylene (UHMW-PE)
Also: UHMW-PE, UHMWPE, UHMW polyethylene, ultra-high-molecular-weight polyethylene, PE 1000, PE-UHMW, TIVAR 1000, Polystone M, GUR (resin), reprocessed UHMW, cross-linked UHMWPE (implant), Dyneema / Spectra (UHMW fiber)
UHMW polyethylene: the most abrasion-resistant, impact-tough, slippery low-cost plastic, for wear strips, liners and guides. Soft and springy; not precise.
Sourcing UHMW parts or stock?
- Machine shops that work with plastics · 189
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- All U.S. manufacturers working with plastics · 1,204
At a glance
| Density | 0.93 g/cm³ (0.034 lb/in³) |
|---|---|
| Tensile strength | About 20 MPa (2.9 ksi) at yield; roughly 40 MPa (5.8 ksi) at break after the material draws out |
| Yield strength | About 20 MPa (2.9 ksi) tensile yield |
| Hardness | Shore D 60-66 |
| Elongation | 300% or more at break |
| Modulus of elasticity | 0.6-0.8 GPa (0.09-0.12 Msi) tensile |
| Thermal | Crystalline melt at about 130-138 °C (266-280 °F), but it does not flow; continuous service about 80 °C (180 °F); stays tough down to about -200 °C (-328 °F) |
| Composition | Linear polyethylene, (C2H4)n, with a molecular weight of roughly 3-7 million g/mol (ASTM D4020 sets the floor at about 3.1 million); unfilled, or with glass bead, oil, solid lubricant, UV or antistatic additives |
Typical values, Virgin natural compression-molded sheet (TIVAR 1000 type), unfilled, 23 °C (73 °F). Confirm against the mill certificate and the purchase spec.
- MachinabilityGood
- Cuts easily with sharp, high-rake tools, but it is soft, springy and grows with heat. Chips string, clamping distorts it, and ±0.13-0.25 mm (±0.005-0.010") is a realistic tolerance; tighter needs temperature control and a stress-relieved blank.
- WeldabilityPoor
- It does not flow when melted and resists every common solvent and most adhesives. Specialists hot-plate or extrusion weld it; bonding needs flame, plasma or corona treatment and a polyolefin adhesive. Countersunk screws in slotted holes are the standard joint.
- FormabilityFair
- Thin sheet cold-bends to gentle curves for chute and truck-bed liners, held by fasteners. Hot forming near the melt works but springs back (elastic memory); it is not a thermoforming sheet.
- Corrosion resistanceExcellent
- Resists nearly all acids, bases, salts and solvents at room temperature, absorbs no water, and does not rot. Strong oxidizing acids attack it, and aromatic and chlorinated hydrocarbons swell it when hot. Natural grades degrade in sunlight; use black UV-stabilized stock outdoors.
UHMW-PE is polyethylene with a molecular weight of several million (typically about 3 to 7 million g/mol), roughly ten times that of ordinary HDPE. The very long chains tangle so thoroughly that it resists sliding abrasion better than almost any other plastic, and better than carbon steel in producers' sand-slurry tests. It does not break in a notched impact test, has a low, self-lubricating coefficient of friction of about 0.1-0.2 against steel, and absorbs essentially no water. It is the standard material for chute and hopper liners, conveyor wear strips and guide rails, star wheels and timing screws, dock fenders and truck-bed liners.
The same long chains mean it will not flow when melted. UHMW cannot be injection molded, conventionally extruded or printed; it is compression molded into sheet and block or ram extruded into rod and profiles, then machined, sawn or waterjet cut. It is also weak by engineering-plastic standards (about 20 MPa, 3 ksi, at yield), has a modulus under 1 GPa and a thermal expansion near 150-200 um/m·K, so parts are designed as liners, pads and guides with slotted fastening, not as precision structure.
Grades split three ways: virgin natural (white, FDA-compliant), reprocessed (cheaper, off-color, fine for industrial wear), and modified grades with glass beads, oil or solid lubricants, UV stabilizers or antistatic fillers. Medical UHMWPE for joint-replacement bearings is a separate, tightly controlled product (ASTM F648, often cross-linked) and is not interchangeable with industrial stock.
Heat treatment
Not heat treated. Stock is stress relieved by the producer; for flat or precision machined parts, anneal between roughing and finishing at roughly 100-120 °C (212-250 °F), hold about 30 minutes per 6 mm (1/4") of thickness, and cool slowly while supported flat.
Tempers and conditions
- Virgin natural (white)
- Reprocessed (off-color, lower cost)
- Black UV-stabilized
- Glass-bead or ceramic-filled (abrasion)
- Oil-filled and solid-lubricant self-lubricating grades
- Antistatic and conductive
- FDA-compliant virgin grades
- Medical implant grade (ASTM F648)
Stock forms
- Compression-molded sheet and plate
- Block
- Ram-extruded rod
- Ram-extruded profiles (wear strips, guide rails)
- Skived film and adhesive-backed tape
- Powder
Relative cost
Tier 1 of 5. Close to HDPE per pound: roughly 1.2-2x for virgin natural, less for reprocessed. Filled and self-lubricating grades cost more; machining is quick.
Typical applications
- Chute, hopper, bin and truck-bed liners
- Conveyor wear strips, chain guides and guide rails
- Star wheels, timing screws and change parts in bottling and packaging
- Dock fenders, bumper pads and crane outrigger pads
- Food-processing cutting surfaces, scrapers and guides
- Low-friction slide pads and bearing strips
- Joint-replacement bearing surfaces (implant grade only)
Process compatibility
How UHMW takes each process, and what to specify. Each process links to its own guide and to the shops that do it.
| Process | Rating | Notes |
|---|---|---|
| CNC Machining | GoodGood | The usual way to make UHMW parts; cuts fast, but hold realistic tolerances and let parts reach room temperature before measuring. |
| CNC Milling | GoodGood | Routed and milled from sheet at high feed with sharp one- or two-flute cutters; vacuum or screw hold-down, not heavy clamps. |
| CNC Turning | GoodGood | Bushings, rollers and wheels from ram-extruded rod; expect stringy chips and some size recovery after the cut. |
| Gear Cutting | FairFair | Low-load gears and sprockets for wet, dirty or abrasive conveyors; tooth strength and size stability are low, so use nylon or acetal where load or precision matter. |
| Waterjet Cutting | ExcellentExcellent | A standard way to profile thick UHMW plate: no heat, no melt, clean enough edges for wear parts. |
| Laser Cutting | PoorPoor | The cut melts and re-fuses into a rough, rounded edge and the material can flame; thin sheet only. Waterjet or rout instead. |
| Injection Molding | Not recommendedNot recommended | Its melt is too viscous to flow; UHMW is compression molded and ram extruded. Use HDPE or nylon if the part must be molded. |
| FDM 3D Printing | Not recommendedNot recommended | Will not extrude through a nozzle. Print a nylon prototype and machine UHMW for the real part. |
| Vibratory Finishing | FairFair | Knocks down the fuzzy burrs UHMW leaves on small parts; hand deburring with a scraper is often faster on large parts. |
| Bead Blasting | PoorPoor | Too soft and tough to blast usefully: media embeds and the finish barely changes. |
Compare UHMW
Design and sourcing tips
- Design for expansion: at about 150-200 um/m·K, a 2 m (6.5 ft) liner grows about 12-16 mm (1/2-5/8") over a 40 °C swing. Use slotted holes and countersunk screws, and never glue a long strip down.
- Specify virgin natural for food contact and reprocessed for industrial wear where colour and FDA status do not matter; the price difference is real.
- Tolerance it like wood, not like acetal: ±0.25 mm (±0.010") on general dimensions, with any tighter feature called out separately.
- Keep bearing loads, speeds and temperatures modest; UHMW softens as it heats and wears fast above about 80 °C (180 °F).
- Specify black UV-stabilized UHMW for outdoor or sunlit parts.
- If the part must be molded, bonded or welded, choose HDPE or nylon instead; UHMW gives up processability for wear resistance.
Frequently asked questions
- What is UHMW used for?
- Wear and slide surfaces: chute and hopper liners, conveyor wear strips and chain guides, star wheels, timing screws, dock fenders, cutting and scraping surfaces in food plants, and outrigger pads. It is chosen where sliding abrasion, impact and low friction matter more than strength or precision.
- What is the difference between UHMW and HDPE?
- Both are polyethylene. UHMW chains are roughly ten times longer, which makes it several times more abrasion-resistant, much tougher in impact and slightly more slippery. The cost is processability: HDPE molds, extrudes, welds and thermoforms easily, while UHMW can only be compression molded, ram extruded and machined. Use HDPE for tanks, boards and molded parts; UHMW for wear.
- Can UHMW be glued?
- Not reliably. Its low surface energy rejects most adhesives, and it resists all common solvents. Bonding needs a surface treatment (flame, plasma or corona) and an adhesive made for polyolefins, and even then the joint is weaker than the plastic. Countersunk screws in slotted holes are the normal method; adhesive-backed UHMW tape is sold for thin linings.
- Can UHMW be injection molded?
- No. Its melt viscosity is so high that it does not flow through a gate or runner. Sheet and block are compression molded, rod and profiles are ram extruded, and parts are machined from those shapes. If a molded polyethylene part is needed, HDPE is the substitute.
- Is UHMW food safe?
- Virgin natural UHMW grades that comply with FDA 21 CFR 177.1520 are widely used in food and beverage processing. Reprocessed and many colored or filled grades are not food-contact compliant, so specify virgin FDA-compliant material on the RFQ and ask for the certificate.
Processes that commonly use it
Related materials
Where to verify these values
- Mitsubishi Chemical Advanced Materials TIVAR stock-shape data
- Röchling Polystone M sheet data and Celanese GUR resin data sheets
- ASTM D4020 and ASTM F648
- ASTM D638 (tensile) and producer sand-slurry abrasion data
