Torlon | polyamide-imide (PAI) – properties and applications

  • Torlon, also called polyamide-imide (PAI), is a thermoplastic with excellent chemical and physical properties that withstands extreme temperatures and other harsh conditions.
  • PAI is ideal for aerospace industry applications for its corrosive-resistance, wear-resistance, friction resistance and thermal stability characteristics. It is also easy to manufacture.
  • Apart from aerospace applications, the material also finds extensive use in bearings, gears, industrial parts, and oil & gas applications. Read on to find out more.

Do you know a thermoplastic as highly performing as Torlon®? The other name for this strong material is polyamide-imide (PAI). PAI’s excellent chemical and physical properties enable it to perform reliably under harsh conditions at temperatures of up to 260 degrees centigrade. With its outstanding creep and wear resistance, this material finds use in many industrial applications.

Torlon Properties

The high strength of this material is probably the best feature compared to other thermoplastics. Even when under extreme stress, the material still performs excellently at elevated temperatures. Another feature that engineers love about this material is self-lubrication. What this means is that you can use it in any environment. Devices that have lubrication challenges can use this material.

PAI has low coefficient of hygroscopic expansion and thermal expansion. Therefore, it does not change in shape even if the environment is thermally unstable.  You will also be pleased to note that Torlon is approved by many regulatory agencies. It passes most requirements for smoke density, emissions and flammability.

Applications of Torlon plastic

Very few materials match the high standards of Torlon. It outperforms most other materials (even some metals) and is one of the most resilient thermoplastics. With its versatility, it has the strength, insulation and toughness to offer solutions in a wide range of industries. Below are some of the key applications of Torlon.

1. Bearings

If you are interested in a cost effective and innovative design solution, you might want to try a Torlon bearing.

Corrosion is one of the worst enemies of bearings. PAI bearings can work in harsh environments contrary to common bearings. This includes areas such as swimming pools and seawater.

As a plastic, PAI is significantly lighter than metal. Compared to a steel bearing, this plastic bearing requires minimal energy and weight to move.

Even more suitable to the design engineer is the flexibility offered by PAI. Customized designs are easy to make from this material thus giving the engineer the flexibility to design the bearing around the equipment.

Metal bearings demand a lot of lubrication. This is a counter measure for heat, corrosion and friction. First, this material is corrosion-free. Second, there is no issue of metal-to-metal contact so you can forget about heat dissipation.

Other reasons why this material suits bearings include:

  • Noise control
  • High level of hygiene
  • Shock load absorption
  • Lower inertia
Torlon cam sprocket

Polimotor 2 cam sprocket fabricated from Torlon® 7130 PAI. Source: Solvay Specialty Polymers

2. Gears and sprockets

Similar to bearings, gears made from PAI are self-lubricating, low-weight and quiet in operation. Polymer gears have been in existence for years, but PAI is relatively new. Using it in a gear produces a component that not only works in extremely high temperatures, but also offers unmatched strength.

Gears are exposed to continual wear and friction conditions, a good reason why Torlon PAI gears are proving very popular.

Moulded Torlon® scraper blades used for aerospace applications. Source Solvay Specialty Polymers

3. Aerospace Applications

The material’s use in the aerospace industry is what made PAI popular. Materials in this industry need to meet very high standards. Some of these are:

  • Easily manufactured
  • Lightweight
  • Wear-resistant
  • Friction-resistant
  • Corrosive-resistant
  • Able to resist extreme temperatures
  • Able to resist low temperatures

The material has for a long time been the answer to these challenges. There are examples where the material has provided unmatched solutions in this industry.

Fastening screws: WorldWide Aviation Group, LLC needed screws that not only met the load-bearing requirements, but also lowered production requirements. Interference with the radar equipment signal was also an issue to avoid. Since metal screws did not meet these requirements, the company settled for Torlon 4203 screws.

Thermal Isolators:  The Boeing 787 needed hydraulic lines through its fuel tanks. The insulation for these lines had to be capable of handling the intense thermal energy. The natural choice for this application was Torlon 4203 PAI.

Air and Fuel Connects: Stainless steel connects in the F-16 were unsuitable because of lightning strikes. Torlon 4203 solved this problem because it can withstand constant vibrations and 400 degrees temperature.

These examples show why Torlon PAI is considered one of the toughest melt-processable materials.

4. Industrial Parts

This highly reliable thermoplastic is often recommended for precision components. From engine parts used in Formula 1 cars to precision parts in spaceships and many other uses, the material is suitable for wide range of challenging industrial requirements. Its resistance to wear and heat, coupled with incredible strength makes it ideal for extreme conditions.

5. Oil and Gas Applications

The oil and gas industry is also very harsh. Torlon PAI is a reliable material because it can handle extreme heat and pressure. This makes it the material of choice for connector bodies, compressor valves, seals and other components.

Other applications of the material are:

  • Compressor vanes
  • Sliding parts
  • Bushings
  • Transmission
  • Cams
  • Thrust washer

One Response to Torlon | polyamide-imide (PAI) – properties and applications

  1. Steven Weinberg says:

    I've found PAI (and PEI) great economical substitutes when many engineers think PEEK.

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