Tin bronze is a family of copper alloys in which tin is a main alloying element. Depending on the grade, the alloy may also contain lead, zinc, phosphorus or nickel. These additions change its strength, wear behavior, machinability and suitability for casting. Tin bronze is widely used for bushings, gears, wear parts and other industrial components, but there is no single grade that fits every application.
What Is Tin Bronze Made Of?
Tin bronze is based on copper and tin. Compared with pure copper, the addition of tin generally increases strength, hardness and resistance to wear. It also reduces electrical conductivity and can make the alloy more difficult to machine as tin content rises.
The name describes an alloy family rather than one fixed formula. Some cast grades contain mainly copper and tin, while bearing bronzes may also contain lead for improved machinability and anti-seizure behavior. Zinc may improve castability or reduce material cost, and small phosphorus additions may be used for deoxidation or specific mechanical properties.
This is why a drawing should identify a complete grade or standard instead of stating only “bronze.” For a broader explanation of copper alloy families, see What Is a Copper Alloy?
What Does Tin Change in a Copper Alloy?
Tin helps copper provide a more useful combination of strength, hardness, wear resistance and corrosion resistance for mechanical components. Higher-tin cast bronzes are commonly associated with gears, worm wheels and loaded bearing parts. Leaded tin bronzes can offer better machinability, conformability and resistance to seizure, although they normally have lower strength than high-tin grades.
More tin is not automatically better. Increasing tin content can affect ductility, machinability, casting behavior and cost. The correct balance depends on the component, casting process and working condition. See Tin Bronze Advantages and Disadvantages for a more detailed discussion of these trade-offs.
Main Types of Tin Bronze
- Cast tin bronze: Copper-tin alloys produced as castings for bushings, gears, rings and wear parts.
- High-tin bronze: Grades with a relatively high tin content, selected when strength and wear resistance are important.
- Leaded tin bronze: Copper-tin alloys containing lead, commonly used for bearing and sliding applications where machinability and anti-seizure behavior are required.
- Phosphor bronze: Copper-tin-phosphorus alloys often supplied as wrought strip, sheet, wire or bar for springs, electrical parts and selected wear components.
Not every copper alloy containing tin is classified as tin bronze. For example, C83600 contains approximately 4–6% each of tin, lead and zinc, but it is classified as ounce metal or leaded red brass rather than high-tin bronze.
Common Tin Bronze Grades and Material Data
The following values are standard composition ranges. Mechanical properties vary with the casting method, section size and applicable specification.
| UNS grade | Main composition by weight | Classification | Minimum tensile strength, centrifugal cast | Typical applications |
|---|---|---|---|---|
| C93200 / SAE 660 | Cu 81–85%, Sn 6.3–7.5%, Pb 6–8%, Zn 1–4% | High-leaded tin bronze | 207 MPa | General-purpose bushings, bearings and thrust washers |
| C90500 | Cu 86–89%, Sn 9–11%, Zn 1–3% | Gun metal / tin bronze | 276 MPa | Bushings, bearings, gears and pump components |
| C90700 | Cu 88–90%, Sn 10–12% | High-tin bronze | 345 MPa | Heavy-load, relatively low-speed bearings, gears and worm wheels |
| C90800 | Cu 85–89%, Sn 11–13% | Tin bronze | 345 MPa | Worm gears, speed reducers and wear-resistant cast parts |
CuSn10 and CuSn12 are also commonly requested European-style designations, but the complete standard and suffix must be checked before treating them as equivalents to a UNS grade. Chemical composition and mechanical requirements should always follow the purchase specification, drawing and confirmed casting condition.
Where Is Tin Bronze Used?
Tin bronze is used where a component must carry load, resist sliding wear or operate reliably in repeated movement. Common products include sleeve and flanged bushings, plain bearings, thrust washers, gears, worm wheels, rings, wear plates, pump parts and valve components.
For bushings, the material grade is only one part of the decision. Load, speed, lubrication, shaft hardness, surface finish, clearance, temperature and environment also affect performance. Buyers working on demanding machinery can refer to our Tin Bronze Bushing Selection Guide.
How Is Tin Bronze Different from Related Copper Alloys?
Tin bronze uses tin as its main alloying addition. Aluminum bronze uses aluminum and is often considered for higher-strength or impact-loaded parts. Leaded bronze contains lead to improve sliding and machining characteristics. Brass is primarily a copper-zinc alloy.
These families can overlap in application, so material selection should be based on the complete grade and working condition rather than the color or general name of the metal.
Custom Tin Bronze Castings from JEDBUSHING
JEDBUSHING manufactures custom tin bronze bushings, sleeves, rings, thrust parts, bronze wear plates and special-shaped bronze components according to drawings or samples. We can also supply continuous cast bronze tubes as semi-finished blanks or machine them into finished components.
Depending on the part geometry, size, material grade and quantity, our casting capabilities include centrifugal casting, horizontal continuous casting and vertical metal-mold casting. Castings can be followed by CNC machining, composition checks and dimensional inspection.
Send us your drawing, material requirement, quantity and working conditions. Contact JEDBUSHING for a custom quote.
FAQ
Does tin bronze rust?
Tin bronze does not form iron rust, but it can oxidize, develop a surface patina or corrode in unsuitable environments. Actual resistance depends on the grade, chemicals, temperature, water condition and contact with other metals.
Is tin bronze magnetic?
Most common copper-tin alloys are essentially non-magnetic. However, the full composition and any special magnetic requirement should be confirmed for the specified grade.
Can tin bronze be welded or brazed?
It depends on the grade. Some copper-tin alloys have fair welding and good brazing characteristics, while high-leaded grades such as C93200 are generally not recommended for common fusion-welding processes.
Does the casting method affect tin bronze properties?
Yes. Centrifugal, continuous, permanent-mold and sand casting can produce different structures, soundness, mechanical properties and machining allowances. Published values should therefore be matched to the stated casting condition.
How can the grade of a tin bronze casting be verified?
Chemical composition can be checked by spectrometer and compared with the specified standard. Material certificates, heat records, inspection reports and retained samples can provide additional traceability.