Self Lubricating Bronze Bushings for Maintenance-Free Operation
Self-lubricating bronze bushings are dense bronze components with graphite, MoS₂ or PTFE embedded in the matrix, so the bearing builds its own lubricating film while running. Across rolling mills, hydropower stations, marine deck equipment and oven conveyors, this construction replaces routine greasing with a stable transfer film and removes maintenance access as a recurring cost.
This page compares the three grades requested most often — CuSn10 tin bronze, C95400 aluminium bronze and graphite-plugged bronze — across load, temperature, lubrication regime and certification, then links operating conditions to the material that fits the duty cycle.
Years of industry experience
With decades of experience in the bearing industry, we excel in designing and manufacturing high-performance oilless bearings that offer reliable and durable solutions.
Customized solutions
We collaborate with our clients to create bearings that maximize efficiency and durability, considering size, material selection, and performance characteristics.
Trusted by global clients
Our consistent delivery of high-quality bronze bearings and exceptional customer service has fostered enduring partnerships with clients worldwide.
What Is a Self-Lubricating Bronze Bushing?
A self-lubricating bronze bushing is a plain bearing with solid lubricant held inside the bronze matrix. As the shaft rotates or oscillates, micro-quantities of that lubricant transfer to the contact surface and form a stable film, holding the coefficient of friction between 0.04 and 0.16 over long service intervals. Three production methods deliver this effect:
- Cast bronze body with machined lubricant pockets. Graphite or MoS₂ plugs are press-fitted into drilled cavities. Suited to high-load shafts and oscillating pivots where the load path stays predictable.
- Sintered bronze matrix impregnated with oil or PTFE. Impregnation happens under vacuum or pressure. Used in medium-load, variable-speed gearboxes and hydraulic actuators.
- Bimetal strip with a sintered bronze surface. Supplied as flat stock or cut washers, then formed into thrust washers, guide strips and split bearings.
All three share one operating principle: the lubricant film forms during running, so periodic re-lubrication is not required. The practical difference lies in load ceiling, temperature window and how the part responds to shock loading.
Comparing the Three Most Common Alloys
| Property | CuSn10 (Tin Bronze) | C95400 (Aluminium Bronze) | Graphite-Plugged Bronze |
|---|---|---|---|
| Key composition | 88–90 % Cu, 9–11 % Sn | ≈ 81 % Cu, 10–11 % Al, 4–5 % Fe, 4–5 % Ni | CuSn10 or C93200 base with graphite/MoS₂ plugs |
| Tensile strength | ≥ 280 MPa | ≥ 590 MPa | 280 – 480 MPa |
| Hardness | ≈ HB 80 | HB 170 – 210 | HB 60 – 100 |
| Max. operating temperature | ≈ 200 °C | ≈ 260 °C | ≈ 300 °C (intermittent) |
| Static load capacity | ≤ 60 N/mm² | ≤ 100 N/mm² | ≤ 80 N/mm² |
| Seawater corrosion | Good | Excellent | Good (depends on base alloy) |
| Friction coefficient | 0.10 – 0.16 | 0.12 – 0.18 | 0.04 – 0.16 |
| Typical use | Cranes, gearboxes, general machinery | Rolling mills, marine shaft liners | Steel mill conveyors, oven zones, escalator hinges |
Temperature Limits and Lubricant Behaviour
The temperature ceiling of a self-lubricating bronze bushing is set by three limits stacking on top of each other, not by the bronze alone:
- The bronze matrix begins to soften past roughly 280 °C, depending on alloy.
- The solid lubricant softens or oxidises. Graphite stays stable to about 450 °C in inert atmosphere, PTFE is rated near 260 °C, and MoS₂ near 350 °C.
- Thermal expansion mismatch between the bronze and any bimetal backing can set the operating limit below the alloy ceiling.
| Lubricant | Continuous duty ceiling | Intermittent duty ceiling |
|---|---|---|
| Graphite | ≈ 400 °C in air | ≈ 500 °C |
| MoS₂ | ≈ 350 °C in dry air | ≈ 400 °C |
| PTFE | ≈ 260 °C | ≈ 280 °C |
| Oil-impregnated sintered bronze | ≈ 90 °C (oil breakdown) | — |
Because these limits interact, the alloy and lubricant combination should always be confirmed against the supplier’s test certificate before the part enters service. Where a duty cycle crosses 260 °C continuously, nickel-aluminium bronze or a graphite-plugged construction is normally specified rather than a PTFE variant.
Choosing the Right Self Lubricating Bronze for Your Application
Find clear answers to the most frequently asked questions about self lubricating bronze bushings and components.
Matching Alloy to Application
The matrix below reflects the questions the engineering team works through when a drawing arrives. It is a starting point for discussion, not a substitute for a PV calculation on your specific duty cycle.
| Operating condition | Recommended alloy | Reason |
|---|---|---|
| Dry-running conveyor roller, oven zone | CuSn10 + graphite plugs | Runs without a grease film; survives thermal cycling |
| Hydraulic cylinder trunnion, shock loaded | C95400 aluminium bronze | High static load plus corrosion resistance |
| Marine winch bearing, splash zone | CuSn10 + PTFE liner | Stable friction in saltwater; resists galvanic attack |
| Slow-speed journal bearing in a rolling mill | Bimetal strip, sintered CuSn10 surface | Tolerates boundary lubrication; absorbs impact |
| Steam turbine guide bearing | C95400 with MoS₂ pockets | High-temperature strength; resists oxidation |
| Clean-room medical actuator | CuSn10 with PTFE liner | Low particle shedding; FDA-compatible variants available |
When an application crosses two regimes at once — high temperature and corrosive media, for example — moving to nickel-aluminium bronze or adding a surface coating usually resolves the conflict. Where oilless bushings for hydropower are involved, the submerged duty cycle drives the alloy choice more than peak load does.
Custom Manufacturing Workflow
The factory accepts STEP, DWG or PDF drawings and produces prototypes in 10 to 15 working days for standard grades. The full cycle from quotation to shipment runs in five steps:
- Drawing intake. Submit the part geometry, operating conditions and duty cycle. Include static and dynamic load, sliding speed or oscillation angle, temperature, shaft material and hardness.
- Engineering review. Alloy, lubricant pattern and machining sequence are matched against load, PV value, temperature and environment.
- Quotation. Price, lead time, tolerances, packing method and payment terms returned in a single document, normally within one business day once the drawing is complete.
- Production, inspection and export packing. Dimensional inspection and material documentation are prepared with each shipment.
- Shipment and documents. Sea, air or courier freight with commercial invoice, packing list and required certificates.
Material documentation can include mill certificates, RoHS and REACH statements, and FDA-grade lubricant declarations where the application requires them. For parts that also need a graphite-plugged thrust washer or a mating wear plate, both can be quoted from the same drawing set so tolerances stay consistent across the assembly.
Suggested Searches: Copper， Brass， Bronze， Copper Nickel， Manganese， Aluminum
