XXX rod is the solid round-bar form of NEMA Grade XXX paper-phenolic laminate — a thermoset composite produced by impregnating high-grade paper with a specially formulated phenolic resin and curing under heat and pressure into a machinable cylindrical stock. Grade XXX uses a higher-quality paper and resin system than XX, delivering significantly better dielectric performance under humid conditions, making XXX rod the preferred paper-phenolic grade for electrical service in environments where moisture exposure is expected.
XXX rod delivers tensile strength of 14,000 psi, flexural strength of 16,000 psi, and compressive strength of 26,000 psi. Rockwell hardness reaches M105 and shear strength is approximately 11,000 psi. Water absorption over 24 hours is approximately 1.8% — about half that of Grade XX. The material carries a UL 94HB flammability rating and operates continuously up to 250°F (121°C). Dielectric strength is approximately 650 V/mil short-time at 1/16″ thickness, with markedly better insulation resistance after humid conditioning than XX. These properties make XXX rod a reliable choice for terminal posts, insulating bushings, and electrical hardware in radio-frequency and low-humidity-tolerance applications.
Standards & compliance. XXX rod conforms to NEMA LI-1 Grade XXX and meets defense specification MIL-I-24768/13 (Type PBG). Test methods follow ASTM D709. Ready Plastics stocks XXX rod in standard diameters; request a custom cut or contact us for availability.
Sister grades. For lower-cost paper-phenolic where peak humid-condition electrical performance is not required, Grade XX paper-phenolic rod is the standard choice. For higher impact resistance, step up to Grade C cotton-phenolic rod or Grade CE cotton-phenolic rod. When higher mechanical strength and significantly better dielectric performance under all conditions are needed, see G-10 glass-epoxy rod.
