SAE 660 bronze – UNS C93200
High-leaded tin bronze (Cu-Sn-Pb-Zn ≈ 83-7-7-3) for bushings and bearings
SAE 660 (UNS C93200, CuSn7Pb7Zn3) is the most used bearing bronze: about 83% copper, 7% tin, 7% lead and 3% zinc. Tin gives strength and hardness; lead, dispersed as globules, gives good behavior under poor lubrication and easy machining. Supplied as solid and hollow bar (bushing stock), centrifugally or continuously cast.
Designations and equivalents
| System | Designation |
|---|---|
| UNS | C93200 |
| W.Nr./EN | CuSn7Zn4Pb7-C (CC493K, EN 1982)* |
| SAE | 660 (SAE J462) |
| Trade names | Bronze 660, SAE 660, bearing bronze |
| Others | QQ-C-390 E7; QQ-B-1005 Comp 12; MIL-B-11553 Comp 12 |
Standards by product form
| Form | Standard |
|---|---|
| Continuous cast bar and bushing stock | ASTM B505/B505M |
| Centrifugal casting | ASTM B271/B271M |
| Sand casting | ASTM B584 |
| Castings (automotive) | SAE J461 / SAE J462 |
Tolerances and HS codes
- Forged bars (round and square): machining allowance from 2 mm (Ø 6–16 mm) to 24 mm (Ø 400–500 mm) on the diameter. E.g. Ø 100–125 mm finished: +7 mm, tolerance +6 / −0 (length up to 3,500 mm).
- Forged discs: allowance of 4 to 9 mm on the diameter and 3 to 11 mm on the height, plus-only tolerance.
- Cutting and machining: band saw −0 / +5 to +15 mm on length; waterjet +10 % of thickness on the diameter (min. 2 mm); machined parts −0 / +2 to +5 mm on the diameter. See the full tables (INF 002 and INF 003, the same for every alloy).
| Form | NCM (Brazil, 8 digits) | HS (international, 6 digits) | HTS (USA, 10 digits)* | CN (European Union, 8 digits)* |
|---|---|---|---|---|
| Forged bar | 7407.29.10 | 7407.29 | 7407.29.5000 | 7407 29 00 |
| Hot-rolled bar | 7407.29.10 | 7407.29 | 7407.29.5000 | 7407 29 00 |
Tariff class: other copper alloys (by chemical composition, under the Chapter 72 Notes and Section XV Note 5).
*: US and EU codes for reference. NCM per current legislation (General Rules of Interpretation, Notes to Chapters 72, 74 and 75 and Section XV Note 5). Confirm the final code with your customs broker according to the item size and finish. HS = first 6 digits of the NCM.
Chemical composition (%)
ASTM B505/B505M-23 (continuous casting)
| Element | Range (%) |
|---|---|
| Cu | 81.0 – 85.0 |
| Sn | 6.3 – 7.5 |
| Pb | 6.0 – 8.0 |
| Zn | 2.0 – 4.0 |
| Ni (incl. Co) | ≤ 1.0 |
| Fe | ≤ 0.20 |
| Sb | ≤ 0.35 |
| P | ≤ 0.15* |
| S | ≤ 0.08 |
| Al | ≤ 0.005 |
| Si | ≤ 0.005 |
Mechanical properties
Continuous casting, ASTM B505/B505M (minimum values); typical hardness
| Property | Value |
|---|---|
| Tensile strength | ≥ 241 MPa |
| Yield strength (0.5%) | ≥ 138 MPa |
| Elongation (50 mm) | ≥ 10% |
| Brinell hardness (500 kg) | ≈ 65 HB (typical) |
Typical physical properties
| Property | Value |
|---|---|
| Density | 8.91 g/cm³ |
| Melting range | 854 – 977 °C |
| Modulus of elasticity | ≈ 100 GPa |
| Thermal conductivity (20 °C) | ≈ 58 W/m·K |
| Thermal expansion (20–100 °C) | ≈ 17.3 µm/m·K |
| Electrical conductivity | ≈ 12% IACS |
Heat treatment, welding and machining
| Item | Usual practice |
|---|---|
| Service temperature | In bearings, temperature is usually limited by the lubricant, not by the alloy. Lead melts at 327 °C: SAE 660 bushings must not run near that range. |
| Heat treatment | Not hardenable by heat treatment. Stress relief at about 260 °C (500 °F) after heavy machining, when the part needs stability. |
| Welding | Brazing and soft soldering possible (brazing falls in the hot-short range: avoid stress during cooling). Fusion welding (oxyacetylene, TIG/MIG, stick) not recommended because of the lead. |
| Machining | Very good (rating 70): short chips due to lead. Machine bushings with an assembly clearance calculated for the expansion of the bronze (≈ 17 µm/m·K) and of the housing. |
Plan an open-die forging in SAE 660 bronze: reduction, slenderness and how much material to send →Simulate the cutting plan of the ingot or bar →
Typical applications
- Bushings and bearings of machine tools, cranes, rolling mills and presses
- Pivot and lever bushings and stuffing box liners of hydraulic presses
- Thrust washers and bearing shells
- Bushings of water and fuel pumps and pump impeller parts
- Piston pin bushings of diesel engines
Alternatives: TM 23 bronze (high lead) for low speed and poor lubrication; aluminum bronze C95400 or C63000 for high load and shock; PTFE with 40–60% bronze or bearing-grade PEEK when the bushing must run without lubrication, with chemicals or electrically insulated.
Frequently asked questions
What is the chemical composition of SAE 660 bronze?
Per ASTM B505/B505M-23 (continuous casting): Cu 81.0 – 85.0; Sn 6.3 – 7.5; Pb 6.0 – 8.0; Zn 2.0 – 4.0; Ni (incl. Co) ≤ 1.0; Fe ≤ 0.20.
Which standards cover SAE 660 bronze?
Continuous cast bar and bushing stock: ASTM B505/B505M. Centrifugal casting: ASTM B271/B271M. Sand casting: ASTM B584. Castings (automotive): SAE J461 / SAE J462.
Up to what temperature can SAE 660 bronze be used?
In bearings, temperature is usually limited by the lubricant, not by the alloy. Lead melts at 327 °C: SAE 660 bushings must not run near that range.
Which materials can replace SAE 660 bronze?
TM 23 bronze (high lead) for low speed and poor lubrication; aluminum bronze C95400 or C63000 for high load and shock; PTFE with 40–60% bronze or bearing-grade PEEK when the bushing must run without lubrication, with chemicals or electrically insulated.
What is SAE 660 bronze?
It is the leaded tin bronze UNS C93200, with about 83% copper, 7% tin, 7% lead and 3% zinc (ASTM B505). It is the most common bushing and bearing bronze in Brazil, supplied as solid and hollow bar.
SAE 660 or TM 23?
SAE 660 has more tin and is stronger; TM 23 has about 15% lead and better tolerates poor lubrication and shaft misalignment at low speed. For high load with shock, choose aluminum bronze.
Can an SAE 660 bronze bushing be replaced by a plastic bushing?
In many cases, yes: PTFE with 60% bronze or bearing-grade PEEK run dry and do not seize. It depends on load (P), speed (V) and temperature; compare the PV limit of each material before switching.
Where to buy SAE 660 bronze in Brazil?
Dustre supplies SAE 660 bronze as bar, plate, tube, block and forged or machined parts, subject to availability, with a quality certificate. Head office in Osasco/SP, branches in Joinville/SC and Baixo Guandu/ES, with delivery across Brazil. For a quote, message Helena, our assistant on WhatsApp +55 11 98649-0075, or write to [email protected].
