Cotton Phenolic Rod

Cotton phenolic rod is the go-to non-metallic bushing blank for engineers replacing bronze or cast iron in bearing, wear, and electrical-isolation applications — delivering compressive strength over 36,000 psi, self-lubricating cotton fiber structure, and full NEMA LI 1 Grade C or CE compliance in diameters from ½" through 12".

TL;DR — Cotton Phenolic Rod Quick Facts

Standard Sizes — Cotton Phenolic Rod

Per NEMA LI 1 (Industrial Laminated Thermosetting Products):

Commonly stocked diameters: ½, ⅝, ¾, ⅞, 1, 1¼, 1½, 1¾, 2, 2½, 3, 3½, 4, 5, 6, 7, 8, 9, 10, 12 inches.

All tolerances are unilateral positive (oversize) to preserve material for finish turning and boring. Ovality permitted up to 1% of nominal diameter for rods ≤4" diameter.

Cut-to-length service available; minimum cut quantity applies for lengths under 6 inches.

Properties Relevant to Rod Form

Cotton phenolic rod is compression-molded from cotton woven fabric plies impregnated with resol or novolac phenolic resin. The laminated structure runs perpendicular to the rod axis (fabric planes are radial), which optimizes compressive and hoop strength — the loading mode in a bushing or sleeve bearing.

Grade C is the structural workhorse — maximum compressive and flexural strength for bearing and gear applications. Grade CE adds electrical insulating performance while retaining most of the mechanical values of C; select CE when the bushing must also act as an electrical barrier (e.g., insulated motor mounts, pump-shaft isolators on cathodically protected equipment).

For the full property datasheet including water absorption, chemical resistance, and thermal expansion, see the Cotton Phenolic properties page.

Typical Applications — Rod Form

Cotton phenolic rod is almost exclusively machined into rotational or sliding components:

Bushings and sleeve bearings — The primary use. Cotton phenolic bushings replace bronze SAE 660 in applications involving water, dilute acids, caustics, or food-grade lubricant environments where metal contamination is unacceptable. The self-lubricating fiber structure supports dry or oil-impregnated running at moderate PV values (up to ~15,000 psi·ft/min dry, higher with oil impregnation).

Shaft spacers and standoffs — Precision-turned spacers on rotating assemblies, insulating electrolytic corrosion pathways between dissimilar metals on marine shafting.

Wear pads and guide bushings — Turned cylindrical guides for hydraulic cylinder rods, press ram guides, and linear slide bushings where metal-to-metal contact would cause galling.

Gear blanks — Small-diameter rod up to 3" is machined into spur gear blanks for quiet, self-lubricating power transmission in lightly loaded drives (printing machinery, textile equipment, food processing).

Electrical insulating pins and standoffs — Grade CE rod turned into terminal studs, bus bar standoffs, and insulating pins where voltage isolation up to 600 V is required.

Brake and clutch components — Insulating sleeves on electromagnetic clutch-brake assemblies where electrical isolation between actuator and friction face is required.

For a comprehensive application guide by industry, see Cotton Phenolic Applications.

Machining Notes — Rod

Cotton phenolic rod machines well on conventional and CNC turning centers, but the glass-and-cotton-fiber reinforcement demands attention to tooling and hazard control.

Tooling: Use sharp carbide-tipped or solid-carbide tooling. High-speed steel dulls quickly against the abrasive fiber. PCD (polycrystalline diamond) tooling extends tool life in production environments.

Cutting parameters (turning):

• Surface speed: 400–600 SFM
• Feed rate: 0.003–0.008 IPR for roughing; 0.001–0.003 IPR for finishing
• Depth of cut: Up to 0.100" roughing; 0.005"–0.020" finishing
• Coolant: Dry or light mist preferred; flood coolant can cause hygroscopic swelling in thin-wall sections

Boring: Use a sharp boring bar with zero or slightly negative rake. Feed slowly on the final pass — phenolic springs back ~0.001"–0.002" after boring, so undercut by this amount and measure after tool withdrawal before accepting the bore dimension.

Ovality and concentricity: Rough-turn the OD first to remove as-received ovality, then finish bore the ID to maintain concentricity. Do not bore directly from as-received rod in precision bushing work.

Dust and fume control: Cotton phenolic dust is a respiratory hazard. Install localized exhaust ventilation at the cutting zone. Operators must wear NIOSH-rated P100 respirators. No open flames — phenolic dust is combustible.

Parting off: Carbide parting blade, moderate feed. Support the workpiece close to the parting zone to prevent chatter-induced cracking through the rod cross-section.

For detailed tooling specifications, flood-coolant guidance, and surface finish guidance, see the Cotton Phenolic Machining Guide.

Standards and Compliance

Request a Certificate of Conformance (C of C) on every order. For MIL-spec applications, specify the full documentation set at order entry — retroactive certification is not available.

More related guides

Applications

• Bushings & Bearings — Material Selector
• Electrical Insulation — Phenolic & Laminate Options

Industries

• Aerospace Plastics
• General Industrial Plastics

Compare materials

• Cotton vs. Linen Phenolic
• Cotton vs. Canvas Phenolic
• Nylon vs. Cotton Phenolic

Other cotton phenolic forms

• Cotton Phenolic Sheet
• Cotton Phenolic Tube