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ULTEM CNC Machining

Get instant quotes on custom ULTEM machined parts with our Online CNC Machining Service. Make quick turn prototypes and production parts in days with free standard shipping on all US orders. ISO 9001:2015, ISO 13485, and AS9100D certified. ITAR registered.

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ULTEM CNC Machining

ULTEM, or polyetherimide (PEI), is a high-performance engineering thermoplastic with various beneficial properties. These include high strength and stiffness, high temperature and chemical resilience, exceptional electrical insulating properties, biocompatibility, and great machinability via CNC machining. ULTEM is primarily available in amber (natural) and black.

ULTEM is an amorphous thermoplastic that can continuously operate at temperatures up to 340°F and has a UL94 V-0 flammability rating. Having one of the highest dielectric strengths of any commercially available thermoplastic, ULTEM is excellent when used as an electrical insulator. CNC machining in ULTEM is a common way to manufacture parts for use in extreme environments that require mechanical strength, electrical insulation, and/or high-temperature resistance. Applications include components for the medical, aerospace, and automotive industries.

ULTEM at a Glance


Electrical insulators, reusable medical devices, underwater connection components, and structural components


Hydrophobic, biocompatible, exceptional dielectric strength, flame retardant


High cost, notch sensitive, incompatible with strong bases and some halogenated solvents

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.




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 ULTEM 1000

Machining ULTEM 1000 allows for a wide array of applications that take advantage of this material’s exceptional properties. Thanks to it's high strength and ability to operate at high temperatures; it is a great material for aerospace applications. It is also hydrophobic and stable when exposed to steam or boiling water, making it suitable for components in reusable medical devices. While generally resistant to a broad range of chemicals, care does need to be taken with certain types, such as strong bases and some halogenated solvents, which can attack the material. ULTEM 1000 is also known for it's exceptional dielectric strength, making it one of the best options for demanding electrical applications.

General ULTEM 1000 Properties
Tensile Strength, Yield (MPa)Elongation at Break (%)Hardness (Rockwell M)Heat Deflection Temperature (°C)Glass Transition Temperature (°C)
Tensile Strength, Yield (MPa)

90-110 MPa

Elongation at Break (%)


Hardness (Rockwell M)


Heat Deflection Temperature (°C)


Glass Transition Temperature (°C)


ULTEM 2300

ULTEM 2300 is a 30% glass-filled grade of ULTEM. The glass fibers in the material help enhance its dimensional stability, rigidity, and tensile strength. Like other grades of ULTEM, it can perform continuously under very high temperatures making it an excellent option for applications that involve high levels of heat and require strength, such as with structural components used in aircraft.

ULTEM 2300 Properties
Tensile Strength, Yield (MPa)Elongation at Break (%)Hardness (Rockwell M)Heat Deflection Temperature (°C)Glass Transition Temperature (°C)
Tensile Strength, Yield (MPa)


Elongation at Break (%)


Hardness (Rockwell M)


Heat Deflection Temperature (°C)


Glass Transition Temperature (°C)



ULTEM parts are available in a natural translucent to opaque amber color, depending on grade. Black is also available.

As Machined: ULTEM is easily machined and can achieve smooth surface finishes comparable to 125 uin Ra finish or better. 

Bead Blast: Any undesirable tool marks may be removed by mechanically abrading the surface with glass beads.

    Amber colored part

    Cost-saving Design Tips

    Due to the material’s relatively high cost when compared to other plastics, overhead manufacturing costs should be minimized. You can achieve this by following CNC design best practices, such as minimizing complex geometry and appropriate use of internal corner radii. Other design strategies can be found in our CNC Machining Design Guide.

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