Round Rod in PPE FR 3048 mm gray

Round rod in PPE FR in gray is the turning blank for flame retardant parts: insulators, spacers, bushings and fasteners in environments where fire rating is a hard requirement rather than a bonus. The material is a modified polyphenylene ether with the flame retardant built into the polymer; there is no surface layer that can wear off, the property runs through the whole cross section no matter how much you turn away. That simplifies both production and quality work.

The fire performance in numbers: V0 according to UL 94, the strictest class on the scale, plus documentation according to FAR 25.853, the aviation requirement for flammability of cabin materials; the standard sets limits on both ignitability and burn time. Smoke development is low, which in enclosed spaces such as aircraft cabins and railcars weighs at least as heavily as the flame retardant itself; it is rarely the flames that make the cabin environment dangerous first, it is the smoke.

The density is 1.1 g/cm³. That makes the grade one of the lightest flame retardant engineering plastics, an argument that carries real weight in vehicles where every gram counts over the whole service life. Water absorption is at the same time very low; turned parts hold their dimensions whatever the season and the humidity, and the material's good electrical insulation makes it a natural choice for insulators and feedthroughs.

The dimensions give away the grade's home market. The rods come in 12.7 and 19.05 mm diameter, that is half an inch and three quarters of an inch respectively, and the length 3048 mm corresponds to ten feet. The material is made for an international aerospace industry that still counts in inches; if you design in millimeters, you simply start from the raw dimension and turn it down to the size you want. Ten feet gives plenty of blank length per rod, and cut pieces take up little room in the material rack.

Typical parts in Swedish industry: electrical insulators and feedthroughs, spacer sleeves in panels, guide pins, threaded fasteners and small mechanical components at subcontractors to the aerospace, rail and bus industries. The gray color is often asked for in visible interior parts where black reads as too hard against the rest of the fittings, or where fitters need to tell material grades apart quickly. The parts being light as well makes them easier to mount high up in car bodies and panels.

PPE FR is rewarding to machine. The grade is turned, milled, drilled and tapped with ordinary sharp tools and holds tight tolerances thanks to the low moisture movement; commercial PPE is also modified precisely so that it behaves well in the machine. Maximum operating temperature is 85 °C, enough for interiors and electronics but worth checking near heat sources. Keep the material away from aromatic solvents, both when cleaning and when bonding; polyphenylene ether is sensitive there, and mechanical fastening is the safe joining route.

Compare it with POM or PA and those grades are both tougher and cheaper, but they burn, and in vehicle interiors that is usually disqualifying in itself. Flame retardant PC is an alternative where impact strength matters more, at the cost of higher density. With a requirement list of fire rating, low weight and electrical insulation, PPE FR holds up very well in the comparison.

The same grade is also available in black, and as sheet for milled blanks. We cut the rods on request through CTS, our cut-to-size service; exact mechanical and electrical values along with fire certificates are in the manufacturer's TDS.

Do you want a data sheet or fire certificates before you settle the material choice? Get in touch with us.