Sealing Products

Plain Bearings & Bushings

Sliding bearings for rotary and linear motion — every size and material, from standard bushings to custom-machined sleeves.

Overview

Unmatched strength and longevity in sliding motion

Plain bearings (also called sliding bearings or bushings) are the simplest and often the most reliable solution for supporting loads in rotating or linear motion applications. They operate on the principle of a sliding contact between two surfaces — a shaft and a bore — separated by a thin film of lubricant or a low-friction bearing material that eliminates direct metal-to-metal contact.

The concept is not new: Babbitt metal, invented in 1839, was the bearing material that made the industrial revolution's steam-powered machinery possible. Since then, bearing materials have evolved dramatically — today's self-lubricating PTFE composite, filament-wound fiberglass, and sintered bronze bearings deliver performance that Babbitt-era engineers couldn't have imagined.

The distinction between a long-running bearing and one that fails in months comes down to material quality, dimensional precision, and alloy composition — not the appearance of the part. We supply bearings in every size and material, from standard DIN catalogue dimensions to custom-machined sleeves and flanged bushings.

Clearance is everything: Plain bearing clearance must be matched to shaft tolerances, operating speed, temperature, and lubricant viscosity. Too tight and the bearing generates heat and seizes. Too loose and the shaft wanders, creating edge loading that destroys the bearing in days. When replacing a bearing, always measure the worn shaft and housing bore before ordering.

Design Reference

Selection parameters

Material selection by application

Material	PV Limit (MPa·m/s)	Best Application	Limitations
Bronze (CuSn, CuPb)	1.5–3.0	Heavily loaded, well-lubricated. Hydraulic cylinders, construction equipment pins, marine.	Requires good lubrication. Galvanic compatibility must be considered with shaft material.
Bronze + graphite plugs	1.0–2.0	Oscillating motion, slow-speed high-load. Excavator linkages, agricultural pivots, press tooling.	Not suitable for continuous rotation. Graphite degrades if flooded with incompatible lubricants.
PTFE composite	0.1–0.3	Dry running, food contact, chemical environments, low loads. Maintenance-free operation.	Low load capacity. Not suitable for heavy impact loads. PTFE cold-flows under sustained high pressure.
PTFE + fiberglass filament-wound	0.3–0.5	Structural bushings with PTFE bearing surface. Higher load capacity than PTFE sheet. Osmotic pump rods, water-lubricated applications.	More expensive. Minimum bore size constraints from winding process.
Polymer composite (Iglidur, Igus type)	0.2–0.6	Light-duty, maintenance-free, cost-effective. Automation, conveyor pivots, small oscillating assemblies.	Lower load and temperature capacity than metal. Good option when replacing greased bronze in light service.
Bimetal (steel backing + bronze/Babbitt overlay)	3.0–6.0	Engine main and connecting rod bearings, high-speed rotating shafts, turbomachinery. Hydrodynamic film lubrication required.	Requires continuous pressurized oil supply. Fails rapidly if oil supply is lost.

PV = pressure × velocity (MPa × m/s). The PV limit is the maximum combined load that the bearing material can sustain without generating destructive heat. Always verify with the manufacturer's data for the specific grade.

↗ Technymon Plain Bearing Technical Reference

Lubrication regimes

Regime	Condition	Typical Materials
Hydrodynamic (full film)	Continuous rotation at speed. Pressurized oil supply maintains full separation of bearing and shaft surfaces.	Bimetal bearings. No direct contact — longest bearing life if oil supply maintained.
Boundary lubrication	Start-stop, slow oscillation, or intermittent motion where full film cannot develop. Metal-to-metal contact occurs at peaks.	Bronze + graphite, PTFE composite, polymer composites. Material must tolerate intermittent contact.
Dry running (no lubricant)	Applications where contamination of lubricant is unacceptable, or where re-lubrication is impossible.	PTFE composite, carbon-graphite, specialty polymers. Significantly lower load and speed limits apply.

Materials

Available bearing materials

CuSn8 Bronze

Up to +180°C

Standard tin bronze for general industrial use. Good corrosion resistance, compatible with mineral oil lubrication. Most widely used plain bearing alloy.

CuPb24Sn Bronze

Up to +150°C

Lead-bronze for higher load capacity and conformability. Engine applications, heavy machinery. Lead content provides emergency run-dry capability.

Sintered Bronze (oil-impregnated)

Up to +120°C

Self-lubricating — oil stored in porous structure is released during operation. No external lubrication required for moderate loads and speeds.

Bronze + Graphite Plugs

Up to +300°C

High-temperature or contaminated environments where oil lubrication degrades or is impractical. Excellent for oscillating pins and bushings in heavy equipment.

PTFE Composite

–200°C to +260°C

Maintenance-free, chemically inert. Food and pharmaceutical equipment, outdoor exposed applications, clean-room environments.

Filament-Wound PTFE/Glass

–200°C to +200°C

Higher load capacity than PTFE sheet. Water-lubricated or dry running structural bushings. Pumps, marine, chemical processing.

Polymer Composite (PA, POM, PEEK)

Up to +250°C (PEEK)

Light-duty maintenance-free applications. PA and POM for everyday automation and conveyor use. PEEK for high-temperature or chemical environments.

Bimetal (Steel + Overlay)

Application-specific

Heavy rotating machinery, diesel engine bearings. Steel structural backing with Babbitt, copper-lead, or aluminum alloy bearing surface. Maximum load capacity.

Need plain bearings for your application?

Send us shaft diameter, housing bore, load, speed, and operating environment — we'll specify the right material and supply in the exact dimensions you need.

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