A Guide to PI CNC Machining

Key Takeaways

• PI offers exceptional heat resistance, mechanical strength, and dimensional stability across extreme temperatures.

• Its high purity, low outgassing, and wear resistance make it ideal for semiconductor, aerospace, and vacuum applications.

• Moisture absorption and limited stock sizes should be considered when selecting PI for precision components.

Overview

PI (polyimide) is a super engineering plastic with exceptional heat resistance. Unlike PEEK or PPS, PI is non-thermoplastic and does not melt when exposed to heat, allowing it to maintain high mechanical strength even at elevated temperatures.

Its continuous use temperature is 300°C, with short-term tolerance up to 400°C. It can also perform at the opposite extreme, remaining functional down to -270°C. PI has a low coefficient of thermal expansion, giving it excellent dimensional stability across a wide range of temperatures. Its strong sliding performance and wear resistance make it well suited for long-term use in sliding components operating in high-heat environments.

High purity and low outgassing make PI a common choice in semiconductor manufacturing equipment, vacuum systems, and aerospace components.

Key Characteristics

• Excellent mechanical strength and wear resistance

• Excellent heat resistance

• Non-thermoplastic

• Electrical insulation

• Usable at cryogenic temperatures

• Excellent dimensional stability across temperature changes

• High purity and low outgassing

Types of PI

In addition to the standard grade, PI is available in several specialty grades with enhanced or added properties.

• Standard grade

• Antistatic grade

• Graphite-compounded grade

• PTFE-compounded grade

• Molybdenum disulfide-compounded grade

Material Selection Notes

PI absorbs moisture, which can cause changes in both dimensions and material properties. Standard stock sizes are also limited, so it may not always be possible to source material in the exact size needed for a given part.

• Moisture absorption

• Limited standard stock sizes

PI CNC Machining at Yumoto Electric

Yumoto Electric manufactures custom PI machined parts starting from a single piece. We have experience with over 200 materials, including metals such as aluminum alloys, stainless steel, molybdenum, and titanium; and engineering plastics including PEEK, POM, and MC Nylon.

If you’re unsure about material selection or machining methods, we offer complimentary consultations to help optimize your design and production. For any questions, please feel free to contact us.