PAI Rod - 30% Glass, Compression Molded (Torlon 5530)

Polyamide-imide, PAI, is the highest-performing melt-processable thermoplastic there is. It holds more strength and stiffness at 500F than most plastics have at room temperature, it creeps almost not at all, and it machines to tight tolerance. It is also expensive and slow to make - every stock shape goes through a multi-week cure cycle before it ships - which is why it is specified only where nothing cheaper survives.

This is the compression-molded 30 percent glass grade, and the reason to choose it over the extruded 5030 is direction. Compression molding leaves the glass fiber randomly oriented, so properties are much closer to equal in every axis, where extruded stock is measurably anisotropic. It is also the route to thick plate and large geometry that extrusion cannot produce.

Published figures: tensile strength 15,000 psi, flexural strength 20,000 psi, compressive strength 27,000 psi, notched Izod 0.7 ft-lb/in, Rockwell E85, heat deflection 520F at 264 psi, coefficient of thermal expansion 2.6 x 10-5 per F, water absorption 0.3 percent at 24 hours. Specific gravity 1.61. So you give up roughly a third of the extruded grade's strength to get it equally in all directions.

Be aware where these figures come from. They are stock-shape figures off supplier tables rather than a manufacturer datasheet - we could not obtain a primary datasheet with test methods for this grade, and the one modulus figure in circulation is published as flexural by one source and tensile by another. There is also no resin datasheet behind this grade to compare them against, because it is not a resin grade. Treat them as typical supplier data, and if your part depends on a number, ask us and we will get the mill certificate.

A naming point that matters more here than on the other three. "5530" is not a resin grade in the resin producer's current catalog at all - it is a shape maker's designation for compression-molded stock made from the 5030 glass-filled resin. So the honest description is compression-molded 30 percent glass-filled PAI, with "Torlon 5530" as the name the trade uses for it.

Temperature, which is the reason to buy it: glass transition is 527F and it is the same for every grade, because it is a property of the polymer rather than the filler. Long-term continuous service in air is 500F. Heat deflection at 264 psi runs 520 to 532F depending on grade. Note that PAI is amorphous - it does NOT melt at 527F, and a datasheet row reading "melt point 527F" is a mislabeled glass transition.

Machining notes. Positive-geometry ground-periphery inserts, fine-grain C-2 carbide for short runs and polycrystalline diamond for production, tight tolerance or any of the reinforced grades - all four grades are abrasive and will move your tool offsets over a long run. Unlike most of the laminates, PAI DOES want flood coolant for single-point threading, for drilling holes under an inch, and for tapping; deep-hole drilling without enough coolant cracks the part. Use 360 degree chuck pressure and soft or pie jaws on thin-wall tube. Excessive tool rubbing tears material out and looks exactly like localized porosity on an inspection report.

Torlon is a registered trademark of Syensqo and we are not affiliated with or endorsed by them. The generic name is polyamide-imide, PAI - not polyamide, which is nylon, and not polyimide, a different family.