Technical overview
Lead bronzes are cast copper-tin-lead alloys. The lead gives anti-seizing, low-friction behaviour under marginal lubrication and makes the alloy easy to machine. C93200, a high-leaded tin bronze, is a general-purpose bearing alloy (machinability rating 70).
C93700, which CDA calls "Bearing Bronze", carries more tin and lead (each about 9–11%). It is used for high-speed, heavy-load bearings and pressure-tight castings.
Grades & standards
Grades are distinct materials — properties and uses below apply to the named grade only.
C93200
High-leaded tin bronze
Composition: Cu 81–85%, Sn 6.3–7.5%, Pb 6.0–8.0%, Zn 1.0–4.0%
- General-purpose bushings and bearings
- Machinability rating 70
Listed specifications: ASTM B505/B505M · ASTM B271/B271M · ASTM B584 · SAE J462
C93700
Bearing Bronze
Composition: Cu 78–82%, Sn 9.0–11.0%, Pb 8.0–11.0%
- High-speed, heavy-load bearings
- Pressure-tight castings
- Machinability rating 80
Listed specifications: ASTM B505/B505M · ASTM B271/B271M · ASTM B22/B22M · AMS 4827 / 4842
Technical properties
| Property | Value | Applies to | Source |
|---|---|---|---|
| Machinability rating | 70 | C93200 | Copper Development Association Inc. |
| Machinability rating | 80 | C93700 | Copper Development Association Inc. |
| Electrical conductivity | 12% IACS | C93200 | Copper Development Association Inc. |
| Melting range | 854–977 °C | C93200 | Copper Development Association Inc. |
Typical or specified values for the named grade from the cited source. Actual values depend on temper, size and the producing mill — rely on the mill certificate for your lot.
Forms
Typical industry forms for this material. They are not a stock list — form, size and availability are confirmed per enquiry.
- Continuous-cast bar (solid & hollow)
- Sand / centrifugal castings
- Machined bushes
Applications & industries
- Bearings and bushings for machinery, cranes and presses
- Machine-tool and main-spindle bearings
- Pump impellers and fittings
- Pressure-tight castings
Selection notes & limitations
- Relatively low strength — not for high-stress structural parts.
- Lead content may be restricted for some end uses.
What to specify when requesting a quote
- 1Grade (C93200 / C93700 or equivalent) and casting method
- 2Bush OD / ID / length, or bar size
- 3Grade and the standard it must conform to (ASTM, EN, IS, UNS or your drawing)
- 4Form and dimensions — thickness or diameter, width, length and tolerances
- 5Approximate quantity, and whether the requirement is one-off or recurring
- 6Intended application, so the grade can be cross-checked before quoting
- 7Documents required — e.g. mill test certificate, chemical analysis, certificate of conformity
- 8Delivery city / site and the date you need material by
Documents buyers may request
Mill test certificate
e.g. EN 10204 type 3.1 inspection certificate, where the producing mill issues one
Chemical analysis report
heat / lot composition against the specified grade
Certificate of conformity
confirming the material meets the ordered standard
Heat / lot traceability
heat numbers marked on material and documents
Dimensional inspection report
for cut-to-size or machined material
Safety Data Sheet (SDS)
especially for lead, beryllium-, cadmium- or lead-bearing products
Which documents can be provided depends on the source mill and is confirmed with each quotation.
Frequently asked questions
Is lead bronze the same as phosphor bronze?
No. Lead bronzes contain substantial lead for anti-seizing bearing performance; phosphor bronzes are tin bronzes deoxidised with phosphorus. Confirm which you need.
Sources & technical references
- C93200 — High-Leaded Tin Bronze (CDA alloy database) — Copper Development Association Inc. (CDA). Checked 2026-10-14.
- C93700 — Bearing Bronze (CDA alloy database) — Copper Development Association Inc. (CDA). Checked 2026-10-14.
