C90500, C90700, and C90800 are high-tin cast bronzes used for bushings, bearings, gears, and pumps. They differ mainly in tin and zinc, but more tin does not automatically mean a better choice.
C90500 SAE 62 is a versatile choice for low-speed, heavy-load parts. C90700 SAE 65 is associated with worm gears and steel mating surfaces. C90800 is a higher-tin option when the drawing or service justifies it. Selection must also consider load, speed, lubrication, shaft condition, casting route, and inspection.
C90500 vs C90700 vs C90800 at a Glance
These ranges aid comparison; the applicable material standard remains controlling.
| Grade | Common designation | Main composition difference | Technical caution |
|---|---|---|---|
| C90500 | SAE 62; gun metal | 9–11% Sn, 1–3% Zn, 0.30% Pb max. | Zinc distinguishes it from the other two grades |
| C90700 | SAE 65; gear bronze | 10–12% Sn, 0.50% Zn max., 0.50% Pb max. | Widely used for gears, but still needs correct lubrication and alignment |
| C90800 | High-tin or gear bronze | 11–13% Sn, 0.25% Zn max., 0.25% Pb max. | More tin does not make every mechanical property higher |
A C90500 chemical composition search may show “gun metal,” while C90700 is usually called gear bronze. Such names do not replace a UNS number. More tin in C90800 can shift hardness, strength, wear, ductility, machinability, and casting response. Values still depend on product form and condition.
Which Tin Bronze Grade Fits the Application?
Start with unit load, sliding speed, movement pattern, lubrication, shaft hardness and finish, temperature, contaminants, and corrosion exposure.
C90500 for General Heavy-Load, Low-Speed Components
C90500 combines strength, wear resistance, castability, and corrosion resistance. Applications include tin bronze bushings, bearings, pump impellers, valve bodies, piston rings, and slow-moving bridge components.
It is a broad high-tin bronze option, not a universal default. A heavily loaded C90500 bushing still requires correct clearance, shaft finish, lubrication delivery, and edge-load control.
C90700 for Worm Gears and Steel Mating Surfaces
C90700 SAE 65 is a traditional choice for worm gears, gear wheels, and high-load sliding parts. In a bronze gear against a steel worm, the bronze member is normally the replaceable wear component. The steel surface should be appropriately harder and finished to avoid rapid scoring.
A C90500 vs C90700 comparison cannot stop at tensile strength. Tooth geometry, contact pattern, sliding velocity, lubricant viscosity, temperature, and finish may decide C90700 performance.
C90800 When a Higher-Tin Grade Is Deliberately Specified
C90800 is considered for high-load wear parts, worm gears, steel-mill nuts, and bushings where its specified high-tin bronze properties match the design. It should not be selected only because its tin range is higher than C90500 or C90700.
A proper C90700 vs C90800 comparison must use the same casting condition and governing specification. Higher hardness or wear resistance may be useful, while reduced ductility or more demanding machining and casting control may be undesirable elsewhere.
What Must Be Specified Beyond the UNS Grade?
An order should identify the UNS alloy, ASTM or SAE specification, casting method, condition, minimum properties, dimensions, machining allowance, quantity, and inspection documents.
ASTM B271/B271M covers centrifugal copper-alloy castings, while ASTM B505/B505M covers continuous cast rod, bar, tube, and shapes. M02 and M07 requirements are not interchangeable. Review centrifugal vs continuous cast bronze before copying one hardness or tensile value into a drawing.
Searches for a C90500 equivalent, C90700 equivalent, or C90800 equivalent often return old names and cross-reference tables. Use them to begin a review, not to authorize substitution. Any material change should be documented and approved before production.
Send Your Drawing for Tin Bronze Casting Review
JEDBUSHING mainly uses centrifugal casting for custom hollow blanks and finished bushings, with continuous cast material considered when the dimensions, quantity, and specification suit that route.
Send the drawing and operating requirements so we can review the alloy, blank size, machining allowance, casting route, and inspection plan before quotation. Contact JEDBUSHING about a new or replacement part.
Frequently Asked Questions
Are C90500, C90700, and C90800 self-lubricating bronzes?
No. Their tin-rich composition does not provide a renewable lubricant supply. Lubrication requirements must be designed separately unless the bushing uses an additional solid-lubricant system.
Is C90500 equivalent to every material described as gunmetal?
No. Gunmetal is a historical and commercial term whose composition can vary by standard and supplier. Confirm the UNS number, governing specification, and required properties rather than relying on the name alone.
Can a worn bushing or gear be reproduced without the original material certificate?
Possibly. Dimensions, wear pattern, service conditions, and representative chemical analysis can support the review, but the original mechanical properties and casting condition may not be recoverable from the used part alone.
Can JEDBUSHING supply a rough centrifugal casting for local machining?
Yes. Specify the blank dimensions, machining allowance, reference surfaces, quantity, test requirements, and whether material documents must accompany the casting.