CU · copper alloy
Bearing Bronze C93200 (SAE 660)
The standard bearing bronze: it machines well, it is soft enough to embed grit, and it runs against a steel shaft without galling. Chips are powdery and the finish is dull rather than bright.
Quoting this material
- Typical lead time
- 7–14 working days
- Condition
- Continuous cast or centrifugal cast
- Achievable finish
- Ra 1.6 µm typical · Ra 0.4 µm best
Machined in-house to your drawing: see the precision CNC machining service and the machine and inspection capability it runs on.
Machinability
Our own 1–10 shop ranking, not a published index: 10 is free-cutting brass C360, 1 is Inconel 718. It ranks how a material behaves on the floor - cycle time, chip control and tool life together. Where a published index exists it is quoted in the note.
The standard bearing bronze: it machines well, it is soft enough to embed grit, and it runs against a steel shaft without galling. Chips are powdery and the finish is dull rather than bright.
Properties as supplied
| Parameter | Value | Unit |
|---|---|---|
| Tensile strength | 240 | MPa |
| Yield strength (0.2%) | 140 | MPa |
| Elongation | 20 | % |
| Hardness | 70 | HB |
| Thermal conductivity | 59 | W/m·K |
| Modulus of elasticity | 100 | GPa |
Hardness, tensile and thermal figures are typical published values for the condition stated. Actual mill certificates govern; send the specification with the drawing and we confirm against the certificate before the material is cut.
Condition
Continuous cast or centrifugal cast
Heat treatment
Not heat treatable. Bronze bearings rely on the microstructure of the casting - the lead and tin phases - rather than on a thermal treatment.
Achievable surface finish
Ra 1.6 µm
Ra 0.4 µm
A good finish matters on a bearing bore, but the material is soft enough that a polished bore is achievable without special tooling.
Tooling and cutting parameters
Cutting speed
- 150–300 m/min (carbide)
Feed
- 0.10–0.30 mm/rev turning · 0.08–0.20 mm/tooth milling
Tooling
- Uncoated carbide, sharp positive rake, generous clearance
Coolant
- Flood or mist; the dust from dry cutting is worth controlling
Starting points for carbide on a rigid setup, not a guarantee. The right numbers depend on the machine, the toolholder and the fixturing - ask and we will say what we would actually run.
Typical applications
- Sleeve bearings and bushings
- Thrust washers and wear plates
- Pump and compressor bearings
- Machine tool slide bearings
- Valve guides
DFM notes for this grade
- Design for lubrication: bronze bearings are supplied with oil grooves, holes or a graphite plug pattern, and the groove layout decides the load capacity
- A bronze bearing running dry against a steel shaft will pick up - the bearing depends on the oil film, not on the material alone
- Casting porosity is normal in a continuous cast bar; a pressure-tight part needs a different process or a machined-from-solid approach
Questions buyers ask
- Why does a bronze bushing outlast a steel one?
- Because it is soft and it embeds contamination. Grit that would score a steel shaft embeds in the bronze and the shaft survives - the bearing is sacrificial by design. The trade is that it wears and eventually gets replaced.
- How is a bronze bushing sized for a press fit?
- With the press-fit deformation allowed for. A thin-wall bronze bushing squeezed into a housing closes the bore by a few hundredths of a millimetre, so the light press fit is specified and the bore is finished after pressing where the tolerance is tight.
Grades we would quote instead
C95400 Aluminium Bronze
4/10Roughly twice the strength of a tin bronze and harder to machine than it looks on a datasheet.
C51000 Phosphor Bronze
6/10The spring bronze: good machinability with enough tin to give real strength and fatigue resistance.
C63000 Nickel Aluminium Bronze
4/10The strongest of the standard bronze families: about the cutting speed of a stainless and the tool wear of one too.