PAI Plastic Machining

Your guide to PAI Plastic Machining



High performance amorphous thermoplastic

Often used instead of metal where there are weight restrictions

Considered the highest performing thermoplastic

PAI has good machinability, but can be hard to source in the UK. There are several other engineering plastics that have similar attributes and yet offer significantly better value for money. Please call our engineering team to chat through your project.

This guide will take you through the main attributes, common applications, notes for designers and suitable finishing and treatments, as well as UK stock sizes and property tables. Don't forget to bookmark the page so you can refer back later.

If you are interested in PAI machined parts, please scroll to the bottom of the page for more information about our service and to request a quote.

PAI Guide: Properties, Applications and Design Considerations


What is PAI?

PAI (Polyamide-imide) is a high performance amorphous thermoplastic which is often used in place of metal components where there are weight restrictions. 

PAI plastic is considered the highest performing thermoplastic. It is available in a number of grades (such as carbon-fibre reinforced, glass-fibre reinforced, PTFE-filled, graphite-filled, unfilled, wear resistant, high strength, low friction) with varying characteristics.

PAI is generally considered to have good machinability.

You may also see PAI referred to as:

  • Tecator®
  • Torlon®
  • Duratron® PAI
Industry Examples: Electrical | Aerospace | Pharmaceutical | Automotive
Typical Components & Applications: Switches/plug components | Bearings | Bushes | Sliding rollers | Insulating parts | Housings | Support rings | Seals | Pistons | Valves | Electrical connectors | Gears | Other components that are subject to high mechanical strength
Main Attributes:
  • High service temperature in air (up to around 260°C continuously)
  • Good UV resistance
  • Excellent dimensional stability
  • Low coefficient of linear thermal expansion
  • High creep resistance
  • Yellow to brown colour
  • Excellent chemical resistance (except strong alkali, oxidising acids & nitrogen containing solvents)
  • Excellent electrical properties
  • High cost
  • Flame resistant
  • High impact strength
  • Can be bonded
  • Low moisture absorption

Note For Designers:

PAI is more expensive than other thermoplastics and not readily available in the UK and so generally only recommended where the outstanding properties are required. It's also worth noting that PAI often requires post-curing (such as heat treating) to achieve maximum wear and chemical resistance which needs to be factored into time and cost.

In most cases, another thermoplastic is likely to be suitable. Have a look at our Polycarbonate and PSU pages to see if these may be suitable alternatives. Otherwise, please feel free to call our Estimation team who will be happy to talk through your options.

Can we meet your PAI plastic machining needs? Contact us now
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Further Reading & Resources

Polymer Database

Science Direct


PAI Plastic Machined Parts


Penta Precision provides the following plastic PAI machining services: 
  • CNC milling
  • CNC turning
  • Prototypes and batch runs
  • Insert installation
  • Part marking
  • Manual milling
  • Manual turning
  • Machining design advice
  • Design for manufacture service

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Plastic Machining


Plastic Machining


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