CNC Machining in UHMW-PE
UHMW-PE is an advanced engineering plastic with exceptional toughness, chemical resistance, and wear-resistance characteristics that are even better than steel. UHMW-PE is widely used in the automotive and marine industries. Its low porosity and chemical inertness also make it food-safe.
About UHMW-PE for CNC Machining
Ultra-high Molecular Weight Polyethylene, or UHMW-PE for short, is a subset of HDPE (high-density polyethylene) compounds with some additional advantages. The material’s extremely long polymer chains help improve its overall toughness. It has a friction coefficient comparable to Teflon, but with better abrasion resistance. CNC machining in UHMW-PE is similar to machining other engineered plastics.
Application | Liners for chutes, chain guide profiles, dock bumper linings |
Advantages | Exceptional abrasion resistance, exceptional toughness, low friction coefficient |
Disadvantages | Not suitable for high temperatures and high levels of creep |
Lead Time | Lead time is generally a minimum of 3 days. However, this can increase depending on availability or if the parts are to be internationally manufactured. |
Price | $$ |
Tolerances | Machining tolerances of 0.010” (0.25 mm) are achievable. |
Wall Thickness | A minimum wall thickness of 0.03” (0.8 mm) is achievable. This can vary depending on the ratio of wall thickness to planar dimension. |
Max Part Size | The maximum size of the part is determined by the machines available and the complexity of the part. |
Generic UHMW-PE
CNC machining in UHMW-PE produces tough and abrasion-resistant parts, making it ideal for applications that are exposed to impact loads and abrasive materials. Common applications include wear plates and seals. UHMW-PE is susceptible to creep and is not ideal for applications in which the parts are under continuous stress.
| Tensile Strength, Yield (MPa) | Elongation at Break (%) | Hardness (Shore D) | Heat Deflection Temperature (°C) | Melting Point (°C) |
|---|---|---|---|---|
Tensile Strength, Yield (MPa) 40 | Elongation at Break (%) 300 | Hardness (Shore D) 66 | Heat Deflection Temperature (°C) 46.7 | Melting Point (°C) 135 |
Finishes
UHMW-PE’s low friction coefficient makes it inherently resistant to coatings since the slick surface is difficult to bond to. While it is best to leave UHMW-PE in its machined state, Xometry can custom finish UHMW-PE with a variety of finishes.
As Machined: This results in a finish with some visible tool marks and surface roughness comparable to 125 uin Ra finish.
Annealing: UHMW-PE can be heated to a temperature that removes internal stresses from machining and therefore increases part performance.
Bead Blast: UHMW-PE can be bead-blasted to remove any irregularities as a result of the cutting process.
Powder Coat: This can be used to introduce a surface layer of color into a part.
Cost-saving Design Tips
CNC machining in UHMW-PE produces lightweight and low-cost components. Listed below are some additional budget-preserving tips.
Sub-assemblies:UHMW-PE can be purchased as sheet or bar stock in varying sizes. It may be beneficial to design parts as separate components that can then be assembled into the final part. It must be noted that UHMW-PE does not work well with adhesives but can be welded.
Additional DFM best practices: These include designing consistent corner radii, designing for larger features instead of multiple smaller features, and using standard tolerances of +/- 0.010.” More tips can be found in our CNC Machining Design Guide.
