PFA Rod

PFA is perfluoroalkoxy - a fully fluorinated melt-processable fluoropolymer, and the short way to describe it is PTFE's chemical resistance in a material you can actually melt-process, weld and see through. Specific gravity 2.15, continuous service to about 500F, and effectively inert to everything short of molten alkali metals and elemental fluorine.

Why pay the premium over PTFE? Three real reasons. It is melt-processable, so it can be welded, heat-sealed and lined into shapes PTFE cannot. It creeps far less than PTFE under sustained load, which matters for a seal or a gasket that has to stay put. And it is far less permeable and translucent to transparent in thin section, so you can see the contents of a line. Against FEP, PFA runs hotter - roughly 500F continuous against FEP's 400F - and has better creep resistance and stress-crack resistance. If none of those three things matters to your part, PTFE is cheaper and we will tell you so.

Published figures: tensile strength around 4,000 psi, elongation at break 300 percent, Shore D hardness around 60, melting point 582 to 590F, continuous service about 500F. Electrically it is excellent and stable - dielectric constant about 2.1 and dissipation factor under 0.0003 across a wide frequency range, with dielectric strength in the hundreds of volts per mil. Thermal expansion is high, as it is for all the fluoropolymers.

Where rod goes: turned fittings and bushings, valve stems and seats, insulating standoffs, seal and gasket blanks, and high-purity semiconductor components machined to size.

Machining notes: it machines much like PTFE - very sharp tools, high rake, light cuts, and plenty of support, because it is soft and will push away from the cutter and spring back. It creeps, so a part clamped hard will take a set. Nothing much sticks to it, so bonding needs surface etching or treatment. It is also degraded by ionizing radiation, which is worth knowing if the part lives in a radiation field - that is one place where cross-linked polystyrene or a polyimide is a better answer.

On FDA and food contact we differ from most of the industry, and here is exactly why. 21 CFR 177.1550 covers perfluorocarbon resins and lists two chemistries. Paragraph (a)(1) is the PTFE and FEP chemistry. Paragraph (a)(2) is PFA - and paragraph (f) limits the (a)(2) chemistry "to use as coatings or components of coatings for articles intended for repeated food-contact use". Solid molded PFA articles are not what that clears. Compliance also depends on extractives testing of the finished article, so it cannot transfer to a billet somebody sawed into plate. Plenty of distributors publish a blanket PFA food-contact claim anyway; we do not. If you need a cleared food-contact fluoropolymer, ask us about PTFE or FEP and we will tell you what the certificate actually covers.

One safety point that genuinely matters. Overheated fluoropolymers give off hydrogen fluoride and other decomposition products, and the exposure is a real occupational hazard - this is the same mechanism behind what is called polymer fume fever. Do not let it reach its decomposition range on a tool, do not smoke near the dust or chips, and use local exhaust. Ask us for the manufacturer's Safety Data Sheet and work to it rather than to this paragraph.