CuSn8 / C52100 Bronze Bearing Bushing
CuSn8 / C52100 Bronze Bearing Bushing
High-Performance Self-Lubricating Bronze Bushing Solutions & Technologies. Minimize downtime, extend service life, and reduce costs for dynamic applications.
CuSn8 / C52100 Bronze Bearing Bushing
Overview
CuSn8 is a solid-solution strengthened copper alloy — a phosphor bronze with approximately 8% tin. The relatively high tin content gives the alloy high strength combined with adequate electrical and thermal conductivity, good spring characteristics, reliable wear resistance and good sliding behaviour. These attributes make it a common base material for plain bearings, sleeve bushings and slide bearings that must operate under load, in contaminated environments, or where maintenance access is limited.
When supplied as cold-rolled strip and formed into a thin-walled cylinder, CuSn8 becomes the standard material for wrapped bronze bushings — bearings that use a pattern of lubrication pockets or oil holes to store and distribute grease across the sliding surface.
High strength
Yield strength up to about 700 MPa in spring temper, supporting heavy radial and oscillating loads.
Wear resistance
Tin and phosphorus content harden the alloy and extend service life under sliding contact.
Corrosion resistance
Good resistance to seawater, industrial atmospheres and many non-oxidizing media.
Sliding behaviour
Works with grease or oil films and tolerates contaminated, dusty conditions.
Material Identification & Equivalent Standards
CuSn8 is referenced under several national and international designation systems. The equivalents below describe the same family of phosphor bronze:
Wrapped bronze bushings produced from cold-rolled CuSn8 strip are generally manufactured and inspected to plain-bearing standards such as ISO 3547 and DIN 1494 for dimensions, tolerances and verification.
Chemical Composition (mass %)
| Element | Cu | Sn | P | Zn | Fe | Ni | Pb |
|---|---|---|---|---|---|---|---|
| Content | remainder | 7.5 – 8.5 | 0.01 – 0.40 | ≤ 0.20 | ≤ 0.10 | ≤ 0.20 | ≤ 0.02 |
The composition is consistent with RoHS requirements for electrical and electronic components and with ELV requirements for the automotive sector, with lead and other restricted elements held to low maximum limits.
Physical Properties
| Property | Value | Unit |
|---|---|---|
| Melting point | 1040 | °C |
| Density | 8.8 | g/cm³ |
| Specific heat capacity, cp (20 °C) | 0.377 | kJ/(kg·K) |
| Young’s modulus | 115 | GPa |
| Thermal conductivity | 67 | W/(m·K) |
| Electrical conductivity (soft condition) | ≥ 7.5 / ≥ 13 | MS/m / % IACS |
| Coefficient of thermal expansion, α (20–300 °C) | 18.5 | × 10⁻⁶ /K |
The stated electrical conductivity applies to the soft (annealed) condition. Conductivity is influenced by chemical composition, the degree of cold deformation and grain size; higher deformation and finer grains reduce conductivity.
Mechanical Properties by Temper
The alloy is supplied in a range of cold-rolled tempers. The table below lists representative values for strip; exact limits depend on thickness and product form.
| Condition | Tensile strength Rm (MPa) | Yield strength Rp0.2 (MPa) | Elongation A50 (%) | Hardness HV |
|---|---|---|---|---|
| Annealed (soft) | 370 – 450 | ≤ 300 | ≥ 50 | 90 – 120 |
| Quarter-hard | 450 – 550 | ≥ 280 | ≥ 20 | 135 – 175 |
| Half-hard | 540 – 630 | ≥ 460 | ≥ 13 | 170 – 200 |
| Hard | 600 – 690 | ≥ 530 | ≥ 5 | 190 – 220 |
| Extra-hard | 660 – 750 | ≥ 620 | ≥ 3 | 210 – 240 |
| Spring | ≥ 740 | ≥ 700 | ≥ 2 | ≥ 230 |
Bend behaviour is described by the ratio r = x · t for thickness t ≤ 0.5 mm, evaluated for bending axes transverse and parallel to the rolling direction. Higher tempers require larger minimum bend radii.
Fabrication Characteristics
| Process | Assessment |
|---|---|
| Cold formability | good |
| Hot formability | limited (not generally recommended) |
| Soft soldering | good |
| Brazing | good |
| Oxyacetylene welding | fair |
| Gas-shielded arc welding | good |
| Resistance welding | good |
| Machinability | limited (not generally recommended) |
Corrosion Resistance
Resistant to
- Natural and industrial atmospheres, as well as maritime air
- Potable and service water at moderate flow rates
- Seawater and marine environments
- Non-oxidizing acids, alkaline solutions and neutral saline solutions
Not resistant to
- Ammonia, halides, cyanides and hydrogen-sulfide atmospheres or solutions
- Oxidizing acids
Compared with many copper alloys, phosphor bronze shows improved resistance to seawater and to pitting corrosion, which supports its use in marine and outdoor equipment.
Wrapped Bronze Bushing Construction
A wrapped CuSn8 bushing is produced by rolling cold-formed, homogeneous bronze strip into a thin-walled sleeve and calibrating it to precise dimensions. The working surface is formed with a pattern of diamond-shaped or circular lubrication pockets, optionally combined with oil holes.
During assembly the pockets are filled with grease or oil, which acts as a reservoir that builds a lubrication film at the start of motion and sustains it during operation. This design reduces running friction and extends relubrication intervals. In contaminated environments the pockets also trap abrasive particles, limiting their contact with the shaft.
Thin wall
Low installed height saves space and reduces component weight versus solid cast bushings.
Lubrication storage
Pockets and holes retain grease, supporting long service intervals.
Contaminant control
Pocket geometry captures dirt and dust away from the sliding interface.
Cost efficiency
Rolled construction reduces material use relative to machined solid bushings.
Application Sectors
Automotive
Suspension linkages, steering columns, transmission bushings, relays, conductor and contact springs, retaining clamps.
Agricultural machinery
Tractor hinge bushings, harvester cutter-bar pivots, tillage wheel hubs operating in mud and dust.
Construction & heavy equipment
Excavator bucket hinges, crane sheave bushings, forklift steering axles under shock loads.
Mining & quarrying
Crusher eccentric shafts, dozer track tensioners in abrasive, high-impact duty.
Marine engineering
Propeller-shaft bushings, winches and anchor-handling equipment exposed to seawater.
Industrial machinery
Gearbox supports, hydraulic piston rods, conveyor rollers, presses and general mechanical engineering.
The combination of load capacity, wear resistance and corrosion resistance makes CuSn8 bushings suitable for low-speed, high-load and oscillating movements where access for maintenance is limited.
Typical Performance Parameters
The values below are representative for wrapped CuSn8 bronze bushings and should be confirmed against the specific product design, lubrication and shaft condition.
| Parameter | Typical range |
|---|---|
| Static specific load | ≤ 120 N/mm² |
| Dynamic specific load | ≤ 40 N/mm² |
| Sliding speed | ≤ 2.5 m/s |
| Friction coefficient (lubricated) | ≈ 0.08 – 0.15 |
| Temperature range | ≈ −40 °C to +200 °C (lubricant dependent) |
| Shaft recommendation | Hardened steel, surface roughness ≤ Ra 0.8 µm, tolerance e7/f7 |
Selection & Design Guidance
Material temper
Choose a softer temper (annealed to half-hard) when forming, flanging or spring action is required; choose a harder temper (hard to spring) when maximum strength and wear resistance are needed and formability is less critical.
Geometry & lubrication pattern
Select wall thickness and pocket/hole pattern according to the expected load, speed and contamination level. Diamond pockets suit general grease retention; perforated or oil-hole patterns help in heavily contaminated or high-speed duty.
Mounting & maintenance
- Apply grease during installation; use a press-fit mandrel and chamfered housing and shaft for alignment.
- Apply a thin film of grease to the outer surface to ease press-fitting.
- Relubricate on a schedule suited to duty; pockets extend the interval but do not remove the need entirely.
- Inspect periodically for wear in high-load or contaminated service.
Frequently Asked Questions
What is CuSn8 / C52100 bronze?
CuSn8 is a solid-solution strengthened copper alloy (phosphor bronze) containing about 8% tin, listed as UNS C52100, EN CW453K, ISO CuSn8, DIN 2.1030 and BS PB104. The tin content provides high strength, wear resistance and good sliding properties.
Which standards apply to CuSn8 bronze bushings?
The alloy is covered by UNS C52100, EN CW453K, ISO CuSn8, DIN 2.1030 and BS PB104. Wrapped bushings are generally produced and inspected to plain-bearing standards such as ISO 3547 and DIN 1494.
Where are wrapped CuSn8 bronze bushings used?
In automotive suspension and transmission parts, agricultural hinges, construction and mining pivots, marine shafts and winches, and industrial gearboxes, cylinders and conveyors.
What loads and speeds can they handle?
Typical wrapped CuSn8 bushings are rated for static load up to about 120 N/mm², dynamic load up to about 40 N/mm², sliding speed up to about 2.5 m/s and lubricated friction around 0.08–0.15.
Is the CuSn8 composition RoHS and ELV compliant?
The specified composition is consistent with RoHS for electrical and electronic components and with ELV for the automotive sector, keeping restricted elements such as lead at low maximum limits.
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