Precautions for CNC machining PEEK

PEEK is a semi-crystalline thermoplastic that can operate continuously at temperatures up to 250°C while also having high chemical resistance, but certain acids, such as sulfuric acid, can dissolve the material. These properties of PEEK make it ideal for use in the medical, aerospace, semiconductor, and oil and gas industries.

CNC machining is a commonly used way to process PEEK, but some skills need to be paid attention to when machining.


PEEK is a processable thermoplastic, but important steps must be taken before, during and after processing to provide the best possible end product.


Annealing is a process performed on PEEK bar to relieve stress and reduce stress and the likelihood of surface cracking of the PEEK material during processing. Annealed PEEK is also less likely to deform. Depending on the time required for processing, multiple annealing stages may be required.

2.Cutting Tools

In most cases, silicon carbide tools can be used to machine PEEK. If PEEK is reinforced with carbon fiber, or if particularly tight tolerances are required, diamond tools should be used. It also prevents contamination if the cutting tool used is not for metal.


PEEK does not exotherm and must be cooled during processing to prevent deformation and cracking. Except for medical components, standard liquid coolants can be used. Medical parts, PEEK materials must be cooled with compressed air, as liquid coolants can affect the biocompatibility of PEEK.


PEEK is less stretchable than other plastics, so deep drilling can cause cracks.

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