TORLON® is the Solvay brand name for polyamide-imide or PAI. Polyamide-imides demonstrate exceptional mechanical, thermal and chemical resistance properties making them well suited to severe environmental service. PAIs have exceptionally high heat performance with a continuous service temperature of 260°C or 500°F and are inherently flame resistant. They are known to have the highest strength and stiffness at higher temperatures of any thermoplastic. Torlon resists wear, creep and is also extremely durable from cryogenic temperatures to 275°C (535°F). Additionally it exhibits a low Coefficient of Linear Thermal expansion. PAI is an amorphous material that does not have a melting point but rather a Tg or glass transition temperature of 280°C (537°F).
Parts made of Torlon® PAI perform under conditions generally considered extreme for most other thermoplastics because they exhibit superior toughness throughout its temperature operating range. Superior toughness when applied to plastics means that material has the ability to absorb energy and plastically deform without fracturing. Another way to think about toughness is also the materials resistance to fracture when stressed. Parts machined from Torlon® stock shapes are known to exhibit greater compressive strength and higher impact resistance than most engineered plastics that are available in the marketplace today.
Another great thing about Torlon® PAI is the chemical resistance that it can bring to the table for your application. It can withstand exposure to both strong acids and organic solvents. It also resists stress cracking in inorganic salt solutions, alkalis, acids and some oils. PAIs are virtually unaffected by aliphatic and aromatic hydrocarbons as well as both chlorinated and fluorinated hydrocarbons, and most acids at moderate temperatures. However, the polymer may be damaged by saturated steam, strong bases, and some high-temperature acid systems.
Torlon® PAI is available in a variety of grades including various unreinforced, glass-fiber filled, carbon fiber reinforced and wear resistant grades. These resins are sold at a relatively low molecular weight so they can be melt processed by extrusion, or compression/injection molding. Some of the more popular grades are 4203, 4301 and 5030. Torlon® 4203 is known for high dielectric strength and thus impressive insulation properties. It is externally brown in color with a unique yellowish core and is commonly used in Baffle and Confinement fasteners, IC Test Sockets and Handlers. Torlon® 4301 extruded PAI is primarily used for wear and friction parts. It offers a very low expansion rate, low coefficient of friction and exhibits little or no slip-stick in use. Torlon® 4301’s flexural modulus of 1,000,000 psi is higher than most other advanced engineering plastics. This grade excels in severe service wear applications such as non- lubricated bearings, seals, bearing cages and reciprocating compressor parts. The Torlon® 5030 grade is a high modulus polyamide-imide. It contains 30% glass fibers and is recommended for high load structural parts as well as electrical insulators and thermal insulators and fasteners. 5030 offers a 50% lower CLTE than the 4203 grade of Torlon®.
Extruded polyamide-imide stock shapes must be post cured for 30 days at temperatures up to 260°C or 500°F. During the post cure the molecular weight increases through chain extension and the material gets stronger and more chemically resistant. Post curing also helps with moisture removal and stress relief before machining finished components.
The grades of Torlon® PAI are used in numerous applications for their versatility from coatings for magnetic wire to molded and machined hardware. Torlon® fasteners such as screws, nuts, bolts, bushings, bearings, and seals are used for high performance solutions in various industries including aerospace, semiconductor and the oil and gas industries. So the next time you have an application that you are looking to improve performance consider using Torlon® PAI and think of Craftech. We are here to help you with your prints, parts and engineering problems!