PL · engineering plastic
Ultra-High Molecular Weight Polyethylene
Cuts easily but badly: it is soft, it moves under clamping and it produces a continuous string of swarf that has to be managed. Nobody specifies it for a tolerance.
Quoting this material
- Typical lead time
- 7–12 working days
- Condition
- Compression moulded sheet or rod
- Achievable finish
- Ra 3.2 µm typical · Ra 1.6 µm best
Machined in-house to your drawing: see the precision CNC machining service and the machine and inspection capability it runs on.
Machinability
Our own 1–10 shop ranking, not a published index: 10 is free-cutting brass C360, 1 is Inconel 718. It ranks how a material behaves on the floor - cycle time, chip control and tool life together. Where a published index exists it is quoted in the note.
Cuts easily but badly: it is soft, it moves under clamping and it produces a continuous string of swarf that has to be managed. Nobody specifies it for a tolerance.
Properties as supplied
| Parameter | Value | Unit |
|---|---|---|
| Tensile strength | 22 | MPa |
| Modulus of elasticity | 0.8 | GPa |
| Hardness | 62 | Shore D |
| Continuous service temperature | 80 | °C |
| Thermal conductivity | 0.4 | W/m·K |
| Density | 0.93 | g/cm³ |
Hardness, tensile and thermal figures are typical published values for the condition stated. Actual mill certificates govern; send the specification with the drawing and we confirm against the certificate before the material is cut.
Condition
Compression moulded sheet or rod
Heat treatment
No heat treatment. If anything the material is annealed by the supplier to reduce the residual stress from compression moulding, because a machined UHMW part will otherwise bow.
Achievable surface finish
Ra 3.2 µm
Ra 1.6 µm
A sawn or machined surface is normal; a polished one is not achievable in a way that survives handling.
Tooling and cutting parameters
Cutting speed
- 300–700 m/min (very sharp uncoated carbide)
Feed
- 0.15–0.40 mm/rev turning · 0.15–0.40 mm/tooth milling
Tooling
- Very sharp uncoated carbide with a high rake; nothing else works
Coolant
- Air blast
Starting points for carbide on a rigid setup, not a guarantee. The right numbers depend on the machine, the toolholder and the fixturing - ask and we will say what we would actually run.
Typical applications
- Wear strips and guide rails
- Conveyor and chute liners
- Food processing surfaces
- Chain guides and sprocket wear parts
- Impact-resistant liners
DFM notes for this grade
- The best abrasion resistance of the common plastics and a very low friction coefficient, which is why it lines chutes and guides rather than carrying load
- It cannot hold a tolerance: thermal expansion is high, it creeps under load and it deflects under clamping. Specify it for what it does, not for a dimension
- The swarf is a long continuous string - plan the chip handling or it will wrap the tool and the operator
Questions buyers ask
- Why use UHMW-PE rather than a steel wear plate?
- Because it does not need lubrication and it does not damage what slides on it. A steel chute liner wears the material it handles; a UHMW liner lets wet or abrasive product slide without sticking or scoring, which is why it lines food and bulk handling equipment.
- Can it be machined to a flatness tolerance?
- Not meaningfully. It will conform to whatever it is clamped against and then relax. If a flat surface is required, the plate is usually stress relieved by the supplier and then skimmed in the fixture it will be bolted to.
Grades we would quote instead
POM-C (Acetal Copolymer)
8/10The best-machining plastic in this catalogue: it produces clean chips, holds a tolerance without drama and takes a fine finish.
PTFE
7/10Soft and easy to cut, but it deforms under clamping pressure and creeps after machining, so holding a tolerance is harder than the cutting suggests.
Nylon 6/6 (PA66)
6/10Machines well when dry, but it absorbs moisture from the air and grows - which is the opposite of what most machined parts are expected to do.