Phosphor Bronze and Tin Bronze for Bearings and Bushings
Manufacture and application of bronze rings, particularly in machinery and equipment.
Phosphor Bronze and Tin Bronze for Bearings and Bushings Materials
Tin bronzes are the load-bearing backbone of the copper-alloy bearing world: the tin content forms the hard intermetallic phases that give the family its wear resistance, and a trace of phosphorus — added as a deoxidiser in phosphor bronze — tightens the grain and lifts fatigue strength. This page covers the wrought strip grades that go into wrapped bushings (CuSn8) and the cast grades for heavier sleeves (CuSn12, C90700, C90500).
Wrought strip versus cast: two different products
The same nominal chemistry behaves differently depending on how it is made, and this family spans both routes:
- Wrought strip (CuSn8, CW453K) is hot-rolled and cold-rolled to thin gauge, then rolled into wrapped (split) bushings per DIN 1494 / ISO 3547. Deformation hardens the strip: a hard temper gives higher static load capacity but less conformability. These bushings are thin-wall, press-fitted, and finish-reamed in place or used as-is.
- Cast grades (CuSn12, C90700, C90500) are sand, centrifugal or continuously cast into sleeves, worm gear rims and heavy wear parts. Casting gives wall thickness and damping that strip cannot provide, at lower strength per area.
Quoting and machining practice differ enough between the two routes that they should be specified separately on drawings, not swapped by the supplier.
Grades in this family
| Grade | Standards | Product form | Typical duty |
|---|---|---|---|
| CuSn8 / CW453K | EN 1652, DIN 17662, UNS C52100 (near) | Strip for wrapped bushings, washers, strip | Thin-wall wrapped bushings, needle-roller backings, spring elements |
| CuSn12 / CC483K | EN 1982 (CuSn12Ni2-C = CC484K) | Continuous / centrifugal / sand cast | Worm gear rims, heavy-duty sleeves, trunnions |
| C90700 | ASTM B505 “graphitic tin bronze” | Continuous / sand cast | General bearings, gear blanks |
| C90500 | ASTM B505 “gunmetal” | Sand / continuous cast | Medium-duty bearings, valve bodies, marine fittings |
Composition limits
| Grade | Cu | Sn | P | Zn | Pb | Ni | Fe |
|---|---|---|---|---|---|---|---|
| CuSn8 / CW453K | rem. | 7.0–9.0 | 0.03–0.35 | ≤0.3 | ≤0.05 | ≤0.3 | ≤0.1 |
| CuSn12 / CC483K | rem. | 11.0–13.0 | ≤0.05* | ≤0.7 | ≤0.3 | ≤0.2 | ≤0.2 |
| C90700 | 88.0–90.5 | 6.3–7.5 | 0.02–0.15 | ≤0.50 | ≤0.50 | ≤1.0 | ≤0.25 |
| C90500 | 86.0–89.5 | 9.0–11.0 | ≤0.05* | 1.0–2.0 | ≤0.30 | ≤1.0 | ≤0.25 |
*CuSn12 per EN 1982 is a low-phosphorus grade; the high-P variant for gears is CuSn12Ni2 (CC484K), which adds Ni 1.5–2.5 for a finer, harder structure. Lead limits are maxima.
Mechanical properties
| Grade / condition | Tensile, MPa | Yield, MPa | Elongation, % | Brinell | Density, g/cm³ |
|---|---|---|---|---|---|
| CuSn8 strip, soft (R330) | ≥330 | ≥180 | ≥42 | ~90 | 8.8 |
| CuSn8 strip, hard (R540) | ≥540 | ≥480 | ≥10 | ~160 | 8.8 |
| CuSn12-GC (continuous cast) | ≥260 | ≥130 | ≥12 | ≥90 | 8.7 |
| CuSn12-GZ (centrifugal cast) | ≥280 | ≥150 | ≥8 | ≥95 | 8.7 |
| C90700 continuous cast | ~275 | ~150 | ~20 | ~85 | 8.78 |
| C90500 sand cast | ~250 | ~110 | ~25 | ~75 | 8.80 |
Values from EN 1652 / EN 1982 (≥ values) and CDA reference data (~ values). The spread between soft and hard CuSn8 strip is the point: temper selection is a bearing design decision, not a formality.
PV behaviour of CuSn8 wrapped bushings
CuSn8 wrapped bushings publish two very different performance envelopes depending on lubrication, and mixing them up is the most common selection error with this product:
| Condition | Static load, MPa | Dynamic load, MPa | Speed, m/s | PV, MPa·m/s |
|---|---|---|---|---|
| Grease, boundary film | ~120 | ~40 | ≤2.5 | ~2.8 |
| Oil, periodic supply | ~120 | 40–70 | ≤10 | 10–16 |
Specify the lubrication state in the RFQ
The same CuSn8 bushing covers roughly a 4× PV range between grease and oil supply. An enquiry that does not state the lubrication method cannot be answered with a meaningful load rating — and the answer returned is usually the conservative one, which inflates the bushing size.
Worm gears and heavy sleeves: CuSn12
CuSn12 is the classic worm-wheel rim bronze. The duty there is not steady sliding but rolling-plus-sliding against a hardened steel worm, which demands a structure the cast Sn-rich phase can provide: a soft matrix carrying hard intermetallic particles that resist scuffing while conforming to the worm profile during running-in. Two practical points:
- Ni-modified CuSn12Ni2 (CC484K) refines the structure and raises hardness for higher sliding speeds and more heavily loaded gears. If the worm gear duty is continuous and hot, the Ni grade is the default choice.
- Casting route matters for gears. Centrifugal casting (GZ) gives a denser, sounder rim than sand casting at the same chemistry — the running surface of a worm wheel is one of the few places where internal soundness directly limits life.
FAQ
- Is phosphor bronze the same as tin bronze?
- Phosphor bronze is a tin bronze deoxidised with phosphorus; the term usually implies wrought strip or high-quality cast product with residual P. CuSn8 is the standard phosphor bronze for wrapped bushings. In bearing catalogues the two names overlap heavily.
- Why do CuSn8 bushing catalogues show two different load ratings?
- One is for grease (boundary lubrication), one for oil. The oil-lubricated PV can be 4× the grease value. Always state lubrication method when requesting bushings.
- Can I substitute C52100 strip for CuSn8?
- C52100 is the UNS designation for the same nominal CuSn8 phosphor bronze chemistry in wrought form. Temper and thickness govern behaviour, so match the temper designation, not just the grade name.
- Should a worm wheel rim be sand cast or centrifugal cast?
- Centrifugal casting is preferred for worm wheels: the running face gets a denser, inclusion-poor structure, which is where scuffing and pitting start. Sand cast rims are acceptable for lightly loaded, intermittent drives.
- What hardness shaft suits CuSn8?
- For boundary-lubricated duty, a hardened steel shaft of roughly 45–55 HRC is the conventional pairing. Below that, wear life drops quickly, especially with abrasive contamination.
Customization Bronze rings
The rings are manufactured to meet exact client specifications, with precise measurements and tailored designs.
Bronze rings Specific Uses
Advantages of Bronze Slip Rings
Precision Machining: Advanced machining techniques ensure tight tolerances and high accuracy, meeting the most demanding specifications.
Selection guidance
| Situation | First choice | Reason |
|---|---|---|
| Thin-wall bushing, press-fit, moderate load | CuSn8 wrapped (DIN 1494) | Standard catalog product, ream-in-place, low cost per piece |
| Spring contacts, electrical connectors | CuSn8 hard temper | Elastic range and fatigue strength of cold-rolled strip |
| Worm wheel rim vs hardened steel worm | CuSn12 / CuSn12Ni2, centrifugal | Scuffing resistance and conformability under rolling-sliding |
| General sleeve, greased, medium duty | C90500 / CuSn12 | Balanced strength and wear behaviour |
| Dust or poor lubrication | Leaded tin bronze or graphite-plugged | Embeddability / dry-running margin — not a tin bronze strength |
Manufacturing Capabilities
Customization and Support
Manufacturers often provide bespoke solutions, working closely with clients to design and produce slip rings that meet specific operational needs. Technical teams can advise on material selection, design optimization, and performance enhancements.
By advanced CNC machining and high-quality bronze alloys, manufacturers can produce slip rings that deliver superior performance, reliability, and longevity in even the most challenging conditions.
