Bearing bronze alloys – which grade for which duty
There is no best bronze for bushings, only the right one for a load, a shaft, a lubricant and a medium. The decision table below sends you to one of five alloy families; the properties table lists composition and strength of all twelve grades from the casting standards; the notes on shaft hardness and lead-free options catch the two mistakes that cost the most bushings.
"Bearing bronze" in catalogues usually means C93200 / SAE 660, but the term covers five families of cast copper alloys used against steel shafts: leaded tin bronzes (soft, forgiving), tin and phosphor bronzes (harder, lead-free), gunmetals (corrosion resistant, light duty), aluminium bronzes (strong, seawater) and high-strength brasses (the strongest, for extreme load).
- Soft alloys (60 – 90 HB) conform, embed dirt and run on unhardened shafts; hard alloys (150 – 225 HB) carry more load but need a shaft of 300 HB or more
- Lead gives emergency lubrication and machinability; lead-free grades need a reliable grease or oil supply
- Every grade below is cast to ASTM B505 / B271, EN 1982 or GB/T 1176 and delivered with the stock certificate
- One set of operating limits applies to greased bushings of all grades – the difference between grades is how they fail, not the design load
Decision table: duty → grade
| Duty | Recommended | Why | Alternative |
|---|---|---|---|
| General machinery, grease, unhardened shaft | C93200 / SAE 660 (RG7, CuSn7Zn4Pb7) | 7 % Pb covers grease gaps, embeds grit, 65–75 HB tolerates a plain steel shaft | LG2 / C83600 for lighter load in water |
| Interrupted or poor lubrication, shock, soft shaft | C93700 / SAE 64 (CuSn10Pb10) | 10 % Pb smears over the shaft when grease is short; tolerates rough and mildly corroded shafts | C93800 / SAE 67 (15 % Pb) for the worst lubrication |
| Lead-free, higher load, hard shaft available | CuSn12 · CuSn10P (B101 / PB1) · CuSn10 | 90 HB and above, best wear and fatigue resistance of the tin bronzes, seawater resistant | C90500 / SAE 62 gear bronze |
| Pumps, valves, fresh water, steam, light load | LG2 / C83600 (CuSn5Zn5Pb5) | Pressure-tight, corrosion resistant, machinability 84; the Commonwealth and JIS CAC406 default | C93200 when the load rises |
| Heavy load, seawater, temperatures above 150 °C | Aluminium bronze C95400 · C95500 | 586 – 655 N/mm² min. tensile, 150 – 195 HB, resists cavitation and erosion | CuAl10Fe3Mn2 (BA1032) where the drawing names it |
| Extreme load at very low speed, shock | C86300 / SAE 430B (CuZn25Al5Mn4Fe3) | 758 N/mm² min. tensile, 225 HB – the strongest cast bearing alloy | C95500 where corrosion also matters |
Not sure? Send load (or shaft diameter and force), speed or oscillation, temperature, medium and lubrication – we recommend the grade with the quotation.
The five alloy families
What each family is made of, how it behaves as a bearing, which grades belong to it and what shaft it needs.
Leaded tin bronzes – C93200 / SAE 660, C93700 / SAE 64, C93800 / SAE 67
Copper with 7 – 10 % tin for strength and 7 – 15 % lead as a soft, insoluble phase that smears over the shaft when the grease film breaks. The more lead, the softer and more forgiving the bearing and the lower its strength: 660 (207 N/mm², 65–75 HB) is the all-round grade, SAE 64 (241 N/mm², 60–70 HB) the choice for poor lubrication and shock, SAE 67 (172 N/mm², 50–60 HB) for the worst lubrication and rough shafts. Shaft: unhardened steel of 150 HB and up is fine. Lead excludes them from drinking-water and food-contact positions.
- C93200 / SAE 660 CuSn7Zn4Pb7
- C93700 / SAE 64 CuSn10Pb10
- C93800 / SAE 67 CuSn7Pb15
Tin and phosphor bronzes – CuSn12, CuSn10P (B101 / PB1), CuSn10, C90500 / SAE 62
Copper with 10 – 12 % tin and little or no lead; phosphorus (CuSn10P) hardens the matrix and forms hard Cu₃P for wear resistance. Minimum 280 – 310 N/mm² tensile and 90 HB (CuSn10: 70 HB) – higher load, fatigue and wear resistance than the leaded grades and good in seawater, but no emergency lubrication and less tolerance of dirt and misalignment. Shaft: hardened or at least 250 HB, Ra 0.8 µm. The lead-free family for RoHS-sensitive and water positions.
- CuSn12 CuSn12
- CuSn10P (ZCuSn10P1) CuSn10P
- CuSn10 CuSn10
- C90500 / SAE 62 CuSn10Zn2
Gunmetal – LG2 / C83600 / CuSn5Zn5Pb5 (Rg5, CAC406, БрО5Ц5С5)
The 85-5-5-5 alloy: 5 % each of tin, zinc and lead. Pressure-tight, corrosion resistant in fresh water, steam and mild chemicals, the easiest of all to machine (84), moderate strength (207 N/mm², 55–65 HB). A light-duty bearing alloy for pump, valve and general machinery bushes where the medium matters more than the load. Shaft: unhardened steel or stainless.
- LG2 / C83600 CuSn5Zn5Pb5
Aluminium bronzes – C95400, C95500 (CuAl10Ni5Fe4), CuAl10Fe3Mn2
Copper with 10 – 11 % aluminium and 3 – 5 % iron, plus 4 – 5 % nickel in C95500. Two to three times the strength of 660 (586 – 655 N/mm² minimum), 150 – 195 HB, excellent resistance to shock, cavitation, erosion and seawater, strength retained to 250 °C and above. Against that: no embedability, high friction if the film fails, and a hardened shaft (min. 300 HB, better 50 HRC) is essential – C95400 on a soft shaft wears the shaft, not the bush. C95400 vs C93200 in one line: three times the tensile strength, twice the hardness, half the forgiveness.
- C95400 CuAl10Fe3
- C95500 CuAl10Ni5Fe4
- CuAl10Fe3Mn2 (ZCuAl10Fe3Mn2) CuAl10Fe3Mn2
High-strength brass ("manganese bronze") – C86300 / SAE 430B / CuZn25Al5Mn4Fe3
A brass by chemistry – 60 – 66 % copper, 22 – 28 % zinc – hardened by 5 – 7.5 % aluminium, 3 % manganese and 3 % iron to 758 N/mm² minimum tensile and 225 HB. The strongest cast bearing alloy, for pins and slewing bushes under extreme load at very low speed, shock and edge loading. Needs a hardened shaft of 300 HB or more, clean lubricant, and protection from dezincification in warm saline water; machines slowly (rating 8). Usable to about 200 °C continuously.
- C86300 / SAE 430B CuZn25Al5Mn4Fe3
Composition and mechanical properties of the twelve grades
Chemical composition ranges and minimum mechanical properties from the casting standard each grade is bought to (ASTM B505 continuous cast / B271 centrifugal cast, EN 1982 GZ / GC, GB/T 1176), plus typical as-cast values where the standard or CDA publishes them. Hardness is Brinell (500 kg for tin bronzes, 3000 kg for aluminium bronze and C86300).
| Grade | Alloy | Family | Tensile strength standard minimum (MPa) | Yield strength (0.5 % ext. / Rp0.2) standard minimum (MPa) | Elongation (%) | Hardness (HB) | Tensile strength typical (MPa) | Density (g/cm³) | Machinability (C36000 = 100) |
|---|---|---|---|---|---|---|---|---|---|
| C93200 / SAE 660 | CuSn7Zn4Pb7 | leaded tin bronze | 207 | 110 | 8 | 65–75 | 240 | 8.93 | 70 |
| C93700 / SAE 64* | CuSn10Pb10 | leaded tin bronze | 241 | 138 | 6 | 60–70 | 240 | 8.95 | 80 |
| C93800 / SAE 67* | CuSn7Pb15 | leaded tin bronze | 172 | 110 | 5 | 50–60 | 207 | 9.25 | 80 |
| CuSn12* | CuSn12 | tin bronze | 280 | 150 | 5 | ≥ 90 | — | 8.7 | — |
| CuSn10P (ZCuSn10P1)* | CuSn10P | tin bronze | 310 | 170 | 2 | ≥ 90 | — | 8.76 | — |
| CuSn10* | CuSn10 | tin bronze | 280 | 130 | 10 | ≥ 70 | — | 8.7 | — |
| C90500 / SAE 62* | CuSn10Zn2 | tin bronze | 276 | 124 | 20 | ≥ 70 | 310 | 8.72 | 30 |
| LG2 / C83600* | CuSn5Zn5Pb5 | gunmetal (leaded red brass) | 207 | 97 | 15 | 55–65 | 255 | 8.83 | 84 |
| C95400* | CuAl10Fe3 | aluminium bronze | 586 | 221 | 12 | ≥ 150 (170 typical) | 620 | 7.45 | 60 |
| C95500* | CuAl10Ni5Fe4 | aluminium bronze | 655 | 290 | 10 | ≥ 190 (195 typical) | 690 | 7.53 | 50 |
| CuAl10Fe3Mn2 (ZCuAl10Fe3Mn2)* | CuAl10Fe3Mn2 | aluminium bronze | 490 | — | 15 | ≥ 110 | — | 7.5 | — |
| C86300 / SAE 430B | CuZn25Al5Mn4Fe3 | high-strength brass (manganese bronze) | 758 | 427 | 14 | 225 typical (3000 kg) | 820 | 7.8 | 8 |
* Typical values per ASTM B505 / B271, EN 1982 and GB/T 1176 for the cast alloy; not a guarantee for a specific part. Test certificates (chemical analysis, hardness) are supplied on request with the order.
Values per ASTM B505 / B271, EN 1982 and GB/T 1176; typical values are not a guarantee for a specific part. Test certificates on request. C93200 and C86300 data checked against the owner-approved material sheets; the other grades are drafted from the standards and under final review.
Operating limits – greased cast bronze bushings
One set of design limits for the whole range under boundary lubrication. C93200 is the reference; the hard grades do not raise the load or speed figures – they extend the life at the limit and survive shock that would deform 660. PV and specific load for a real position are checked in the design guide.
| Parameter | Typical | Unit |
|---|---|---|
| Specific load p, moving | 25 | N/mm² |
| Specific load p, stationary | 45 | N/mm² |
| Sliding speed v | 0.5 | m/s |
| Coefficient of friction | 0.08 – 0.15 | µ |
| Working temperature | −40 … +250 | °C |
| Housing | H7 | ISO 286 |
| Shaft | e7–e8 | ISO 286 |
| Condition | grease or oil, boundary lubrication, steel shaft | |
Confirmed by Slidura, 2026, for grease or oil lubrication without a full hydrodynamic film, steel shaft, fits H7 / e7 – e8. Dry running is not covered by any grade.
Shaft hardness and counterface
A plain bearing is a pair. The shaft should be markedly harder than the bush, so that wear happens in the cheap replaceable part: for the soft alloys – 660, SAE 64, LG2 – an unhardened or quenched-and-tempered steel shaft of 150 – 200 HB is enough; for tin and phosphor bronzes at 90 HB the shaft should be 250 HB or better; for aluminium bronze and C86300 a hardened, ground or hard-chromed shaft of 300 HB minimum, typically 45 – 55 HRC. Running a hard bronze on a soft shaft reverses the pair – the shaft wears and the bush survives.
Surface finish of the shaft: Ra 0.8 µm or finer for all grades; Ra 0.4 µm for the hard alloys at higher speed. Stainless shafts run well against gunmetal and tin bronze; against aluminium bronze they gall unless hardened (martensitic or nitrided).
| Bush alloy | Bush hardness | Shaft, minimum | Shaft Ra |
|---|---|---|---|
| C93200 / SAE 660, SAE 64, SAE 67 | 50 – 75 HB | steel, 150 – 200 HB (unhardened acceptable) | 0.8 µm |
| LG2 / C83600 | 55 – 65 HB | steel or stainless, unhardened | 0.8 µm |
| CuSn12, CuSn10P, CuSn10, C90500 | 70 – 90+ HB | steel 250 HB, hardened preferred | 0.8 µm |
| C95400, C95500, CuAl10Fe3Mn2 | 150 – 195 HB | hardened 300 HB min., 45 – 55 HRC typical, or hard chrome | 0.4 – 0.8 µm |
| C86300 / SAE 430B | 225 HB | hardened 300 HB min., ground | 0.4 – 0.8 µm |
Guideline values from bearing practice; the shaft on your drawing prevails.
Lead-free and low-lead options
C93200 contains about 7 % lead, C93700 10 %, C93800 15 % and LG2 5 % – all far above the 4 % copper-alloy exemption in RoHS and the 0.25 % limit of the US Safe Drinking Water Act, so they are excluded from drinking-water and most food-contact positions and need REACH SVHC notification above 0.1 %. In ordinary machinery bearings they remain permitted and are the standard choice.
Lead-free grades in the programme: CuSn12, CuSn10 and CuSn10P (max. 0.25 – 0.7 % Pb per standard), C90500 / SAE 62 (max. 0.3 %), aluminium bronzes C95400 / C95500 (no lead) and C86300 (max. 0.2 %). They carry the same or higher load but need reliable lubrication and, for the hard grades, a hardened shaft. Tell us if the drawing or the end use is lead-restricted and we quote the lead-free equivalent.
Frequently asked questions
What is the best bronze for bushings?
There is none – the best grade is the one matched to shaft, lubrication and medium. C93200 / SAE 660 is the default for grease-lubricated machinery on unhardened shafts; C93700 / SAE 64 where lubrication is poor; CuSn12 or CuSn10P for lead-free and higher wear resistance with a hard shaft; aluminium bronze for heavy load, seawater and heat; C86300 for extreme load at very low speed.
932 vs 954 – what is the difference?
C93200 is a leaded tin bronze (207 N/mm² min., 65–75 HB) that conforms, embeds dirt and forgives a soft shaft. C95400 is an aluminium bronze (586 N/mm² min., 170 HB) with three times the strength and twice the hardness, which resists shock, cavitation and seawater but needs a hardened shaft and continuous lubrication. Use 932 unless the load or medium demands 954.
Is phosphor bronze good for bushings?
Yes, for high load and wear with a hard shaft and reliable oil or grease: CuSn10P / B101 / PB1 (ZCuSn10P1) has 90 HB minimum, high fatigue strength and hard Cu₃P particles. It is not good where lubrication is interrupted or the shaft is soft or misaligned – there the leaded grades win.
Do harder bronzes need harder shafts?
Yes. The shaft must stay the harder partner or it becomes the wearing part. Aluminium bronze and C86300 need a hardened shaft of at least 300 HB (45 – 55 HRC typical); tin bronzes want 250 HB; the leaded grades and gunmetal run on plain steel.
What is "bearing bronze"?
In North American catalogues, C93200 / SAE 660 – the 83-7-7-3 leaded tin bronze – is sold as "bearing bronze" without further name. In Europe the same alloy is RG7 / CuSn7Zn4Pb7 (CC493K). The term is also used loosely for the whole group of copper alloys that run against steel shafts.
Not sure which grade?
Send load, speed, temperature, medium and how the position is lubricated – we recommend the alloy and quote it.