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CNC Machining in PEEK

PEEK or polyetheretherketone is an advanced engineering plastic with a long list of beneficial properties. These include resilience at high temperatures, abrasion resistance, biocompatibility, resistance to ultra-high vacuum, and exceptional chemical resistance.

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About PEEK for CNC Machining

PEEK is a semi-crystalline thermoplastic that can continuously operate at temperatures up to 260°C while also being highly chemical resistant. It must be noted, however, that some acids like sulphuric acid will dissolve the material. CNC machining in PEEK is a common way to manufacture parts for use in extreme environments that require mechanical strength, chemical stability, and/or high-temperature resistance. Applications include components for the medical, aerospace, and automotive industries.

PEEK at a Glance

Generic PEEK

CNC machining in PEEK allows for a wide array of applications that take advantage of this material’s exceptional properties. PEEK has very few downsides when compared to other engineering plastics. One advantage that sets it apart is its heat resistance. It can operate at high temperatures for longer than most other plastics. Additionally, PEEK is hydrophobic, so it does not readily absorb water, and it also outgasses very little under vacuum conditions. This stability is a great asset. PEEK’s uses include medical applications for temporary implants all the way to aerospace components exposed to extreme vacuum.

General PC Properties
Tensile Strength, Yield (MPa)Elongation at Break (%)Hardness (Shore D)Heat Deflection Temperature (°C)Glass Transition Temperature (°C)

65-120

1.5-110

62-89

182-210

143-155

Finishes

PEEK parts are naturally an opaque grey. Given PEEK’s polymeric structure, paints and coatings are difficult to bond to its surface. However, thanks to its inherent chemical resistance, it is often acceptable to leave parts as machined.

  • As Machined: PEEK is easily machined and can achieve smooth surface finishes comparable to 125 uin Ra finish. 
  • Bead Blast: Any undesirable tool marks may be removed via mechanically abrading the surface with glass beads.
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Cost-saving Design Tips

Due to the material’s high cost, manufacturing overhead costs must be minimized. One method to help manage the cost of CNC machining in PEEK is by requesting annealing during fabrication. This may reduce surface and internal cracking, which will reduce scrap rate and reduce overall costs for the manufacturer. Other design strategies can be found in our CNC Machining Design Guide.

    CNC machining design tip
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