A Guide to PET (Polyethylene terephthalate) CNC Machining

Key Takeaways

• PET offers excellent dimensional stability, low moisture absorption, and high clarity for both mechanical and transparent applications.

• Glass fiber-reinforced PET provides enhanced heat resistance, cold resistance, and mechanical performance for demanding environments.

• PET is susceptible to hydrolysis and has lower strength than many engineering plastics, making grade selection important.

Characteristics of PET

PET (polyethylene terephthalate) is a thermoplastic with excellent dimensional stability.

It comes in two broad categories:

• Amorphous grades (A-PET and G-PET)

• Crystalline grades (C-PET)

*PET in this article refers to crystalline PET.

PET has a transparent or white appearance with high clarity, and like acrylic, it is often selected for covers, displays, and similar applications due to its transparent nature.

It also offers strong mechanical performance and good wear resistance, making it suitable for mechanical components as well. The glass fiber-reinforced grade adds significant heat resistance, with a continuous use temperature of 150°C and a heat deflection temperature of 240°C. Cold resistance is also strong, with the material maintaining its strength down to -60°C.

Key Points

• High clarity

• Excellent chemical resistance

• Excellent heat resistance (glass fiber reinforced grade)

• Excellent cold resistance (glass fiber reinforced grade)

• Electrical insulation

• Low moisture absorption

• Excellent mechanical strength

Types of PET

In addition to the standard grade, crystalline PET is available in several specialty grades with enhanced performance characteristics.

• Standard grade

• Glass fiber reinforced grade

• PTFE-compounded grade

Material Selection Notes

PET is susceptible to hydrolysis in hot water and acidic or alkaline environments. The standard grade also sits on the lower end of the strength spectrum for engineering plastics, so depending on the application, the glass fiber reinforced grade may be the better choice for mechanical components.

• Prone to hydrolysis in hot water and acidic or alkaline environments

• Lower strength compared to other engineering plastics

PET CNC Machining at Yumoto Electric

Yumoto Electric manufactures custom PET 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.