FR-4 Flame-Retardant Glass Epoxy — Rod

FR4 rod is a solid round bar made from NEMA FR-4 flame-retardant glass-epoxy laminate — woven fiberglass cloth impregnated with brominated epoxy resin and cured under heat and pressure. It provides 65,000 psi tensile strength, Rockwell M115 hardness, and a UL 94 V-0 flame rating, making it the preferred glass-epoxy rod for turned insulating components in fire-safety-critical applications.

Ready Plastics stocks FR4 glass-epoxy rod in standard diameters as cut-to-length pieces. Contact us for current size availability and pricing.

FR4 rod is turned and bored using carbide tooling. The woven fiberglass reinforcement is abrasive, so carbide inserts are strongly preferred over high-speed steel. Moderate cutting speeds, positive rake angles, and thorough chip clearance maintain dimensional accuracy and minimize edge chipping. Dust and fiber extraction are essential for operator safety.

FR-4 rod and G-10 rod share essentially identical mechanical properties — both are NEMA glass-epoxy laminates. The key distinction is flame rating: FR-4 is certified UL 94 V-0 (self-extinguishing), while G-10 is rated 94HB. Specify FR-4 wherever UL listing, fire codes, or safety standards require a self-extinguishing material.

FR4 rod is used for insulating bushings, standoffs, spacers, guide pins, and structural supports in UL-listed switchgear, motor controls, relay panels, and electronic assemblies. Its 65,000 psi tensile strength, 0.10% moisture absorption, and UL 94 V-0 rating make it a standard choice wherever both mechanical performance and fire safety are required.