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Precision Plastic and Composite CNC Machining

Best Heat Resistant Plastic for CNC Machining

May 5th, 2022

High temperature machined plastic parts

Many applications and industries require plastic parts and components machined from heat-resistant polymers. These plastic materials must stand up to harsh environments, extreme temperatures, and repeated use without degradation of performance. However, choosing the best high-temperature plastic for your planned use can sometimes be challenging.

Upland Fab is here to help. Our team of highly trained machinists can explain how high-temperature plastics are defined and walk you through common plastic materials used to machine parts for high-heat applications.

Three Factors for Defining High-Temperature Thermoplastics & Thermosets

Numerous elements impact the temperature resistance of any given polymer intended for CNC machining, such as the plastic’s underlying chemistry, any possible additives, and the material’s strength. However, three main factors are used to determine the heat resistance of any given plastic material:

  1. Heat Deflection Temperature (HDT). Also known as a heat distortion temperature, HDT refers to the temperature at which a plastic material deforms under a load. HDT is critical as it impacts decisions made at the design, engineering, and manufacturing stages.
  2. Glass Transition Temperature (Tg). Tg denotes the temperature where an amorphous plastic becomes viscous and rubbery instead of brittle and hard. It will always be lower than the polymer’s melting temperature (Tm), provided the Tm exists.
  3. Continuous Use Temperature (CUT). Sometimes called the continuous service temperature, CUT outlines the maximum high temp a plastic can be used continuously without degrading its mechanical properties over the component’s lifespan.

Plastic Material to Withstand High-Heat Applications

The top consideration for selecting a high-temp plastic material for CNC machining is the conditions of your planned application. Corrosive settings, load requirements, the amount of high-heat exposure, and much more can all impact which plastic is your best choice. If you’re not sure what challenges are involved in your application, let us help.


Vespel is a high-achieving plastic with excellent resistance to temperatures up to 300°C. Due to the plastic material’s dimensional stability, minimal outgassing, and chemical resistance, it’s a good fit for extreme environments. Because of these and other characteristics, Vespel is often used to manufacture:

  • Aerospace components
  • Semiconductors
  • Transportation technology.

While Vespel creates durable and high-quality components, it is tough to machine. Always work with an experienced machinist if you choose Vespel Polymide for CNC machining.


Components machined from Torlon are strong, resistant to deformation, and can withstand temperatures up to 500°F. It exhibits a high level of dimensional stability and is a popular polymer choice for many industries. Some common applications of Torlon are:

  • Transmission seal rings
  • Aircraft and spacecraft components
  • Wind turbine parts.

Like Vespel, Torlon is extremely difficult to machine. The stresses in the plastic material must be adequately managed to avoid critical flaws in the finished product. As moisture absorption must be controlled during handling, dry machining is recommended when working with Torlon polymers.

Polyeteretherketone (PEEK)

High-performing and exceptionally versatile, PEEK is a popular choice for cost-effective heat-resistant plastic material. It creates plastic parts that are strong and stand up to continuous use. A few examples of PEEK applications include, but are not limited to:

  • Consumer electronics
  • Seal rings and manifolds
  • Food and beverage packaging.

It is important to consult with an expert when manufacturing PEEK plastic parts as filled grades of PEEK are easily stressed during CNC machining. Precisely controlled processes are required to anticipate and manage these stresses.


Ultem is generally considered one of the best performing plastics with high-heat resistance. Its popularity comes from its excellent strength, stiffness, and ability to maintain high dimensional stability at temperatures up to 200°C. Many applications seek out Ultem to manufacture:

  • Medical devices
  • Electrical connectors
  • Semiconductor equipment.

Unlike some other plastic materials, Ultem components can be applied in applications involving hot water and steam over periods of extended use. FDA-compliant Ultem grades are also available, making it ideal for food and beverage packaging. Multi-axis CNC machining is best for handling this high-temp plastic.

Teflon® (PTFE)

Teflon is a versatile and popular plastic for manufacturing custom components across many industries. It is resistant to temperatures up to 500°F, has a low coefficient of friction, and features excellent dimensional stability, allowing it to stand up against a wide range of conditions. Some examples of Teflon applications include:

  • Electrical gauges and fittings
  • Construction components
  • Aerospace parts.

Teflon often experiences dimensional changes during CNC machining, and certain techniques must be utilized to handle the material properly. Because it is softer than other polymers, burrs can often be an issue for Teflon CNC machining. Cryogenic deburring can be a solution.

Expert Assistance in Selecting the Right High-Heat Polymer for CNC Machining

With over fifty years of experience CNC machining heat-resistant plastic materials for high-temp applications, Upland Fab is your top source for unparalleled industry knowledge and expert machining capabilities. We work with you to understand your planned application, design your part, and select the best high-heat polymer for your specific component and industry.

Contact us to learn more about our heat-resistant plastic material options, CNC milling services, or CNC turning capabilities. Request a quote to begin manufacturing a plastic part that can withstand high heat.
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