Cast Bronze Metric Sleeves in C93200 (SAE 660)
A cast bronze metric sleeve is a plain cylindrical bearing with metric bore, outer diameter and length dimensions, pressed or slipped into a housing to carry a rotating or sliding shaft. It is the metric counterpart of the inch sleeve series — same alloy, same manufacturing route, different dimension standard — and it is the part most often specified on equipment built to ISO or DIN drawings.
This page covers the C93200 (SAE 660) alloy we use as standard, the size and tolerance range we hold, how the casting method changes the properties, and the lubrication options available. If your drawing is in inches, see cast bronze inch sleeves.
What is a cast bronze metric sleeve
A sleeve is a straight cylindrical bushing without a flange. It differs from related parts in three ways that matter when ordering:
| Part | Geometry | Usual reason to choose it |
|---|---|---|
| Sleeve (this page) | Straight cylinder, no flange | Housing bore takes all axial location; lowest cost per unit |
| Flanged bushing | Cylinder plus a locating flange | Axial thrust needs to be taken at the housing face |
| Thrust washer | Flat ring | Axial load only, no radial load |
| Wear plate | Flat strip or block | Sliding rather than rotating contact |
Because a sleeve relies on an interference or transition fit to stay in place, the housing bore preparation matters as much as the sleeve itself. A housing bored oversize will let the sleeve rotate; one bored undersize can close the bore inwards after fitting and reduce the running clearance.
Cast Bronze Metric Sleeves Material: C93200 (SAE 660) leaded tin bronze
C93200 is the general-purpose bearing bronze used across most of our sleeve range. It is a leaded tin bronze: a copper-tin matrix carries the load, while discrete lead particles dispersed through the structure provide a measure of solid lubrication and make the alloy easy to machine.
Composition
| Element | Range (%) | Role |
|---|---|---|
| Copper (Cu) | Remainder (about 81–85) | Matrix |
| Tin (Sn) | 6.3–7.5 | Strength and wear resistance |
| Lead (Pb) | 6.0–8.0 | Solid lubrication, machinability, embeddability |
| Zinc (Zn) | 2.0–4.0 | Casting fluidity |
| Nickel (Ni) | ≤ 1.0 | Grain refinement |
| Iron (Fe) | ≤ 0.20 | Controlled; hard particles increase shaft wear |
| Phosphorus (P) | ≤ 0.15 | Deoxidiser |
| Antimony (Sb) | ≤ 0.35 | Trace limit |
Equivalent designations
The same alloy appears under different standard systems. Use this table to cross-reference a drawing:
| Standard system | Designation |
|---|---|
| UNS | C93200 |
| SAE | SAE 660 |
| ASTM — continuous cast | B505 |
| ASTM — centrifugal cast | B271 |
| ASTM — sand cast | B584 |
| EN 1982 | CC493K, CuSn7Zn4Pb7-C |
| DIN | 2.1090 (formerly Rg7, G-CuSn7ZnPb) |
| GB/T 1176 | ZCuSn7Pb7Zn3 |
| JIS | CAC406C (BC7) |
Limitation to note before specifying
C93200 contains 6–8% lead. It is therefore restricted under RoHS and REACH, and it is not used for potable water contact. Where lead-free compliance is required, we supply alternatives in aluminum bronze, manganese bronze or lead-free ECO bronze — tell us the compliance regime at enquiry stage.
Mechanical and physical properties
Values differ by casting method. Continuous cast stock is used for most sleeve sizes because the lead phase distributes evenly and the grain is fine; sand castings are reserved for large or one-off sections.
| Property | Continuous cast | Centrifugal cast |
|---|---|---|
| Tensile strength | 300 MPa (43,000 psi) | 240 MPa (35,000 psi) |
| Yield strength | 150 MPa (22,000 psi) | 135 MPa (20,000 psi) |
| Elongation in 50 mm | 20% | 20% |
| Brinell hardness | 60 HB typical | 60 HB typical |
| Property | Value | Why it matters in a sleeve |
|---|---|---|
| Density | 8.9 g/cm³ | Weight for handling and shipping estimates |
| Thermal conductivity | about 59–62 W/(m·K) | Carries frictional heat out through the housing |
| Machinability rating | 70 (free-cutting brass = 100) | Grooves and oil holes are cut without difficulty |
| Maximum operating temperature | 230 °C (450 °F) | Above this the alloy softens; check your duty cycle |
| Stress relieving temperature | 260 °C (500 °F), 1 h per 25 mm section | Used after rough machining on close-tolerance parts |
Standard metric sizes and tolerances
Standard inner diameters run from 2 mm to 100 mm. Larger bores, non-standard wall thicknesses and lengths outside the stock range are machined to drawing.
| Dimension | Size band | Tolerance |
|---|---|---|
| Inner diameter | up to 76.2 mm | ± 0.0254 mm |
| Inner diameter | over 76.2 mm | ± 0.0381 mm |
| Outer diameter | up to 76.2 mm | +0.0508 mm / +0.0762 mm |
| Outer diameter | over 76.2 mm | +0.0762 mm / +0.127 mm |
| Length | all lengths | ± 0.127 mm |
These are stock tolerances. Two points are worth confirming before you design around them:
- The bands follow an inch-derived schedule — 76.2 mm is 3 inches, and the tolerance steps correspond to 0.001 in, 0.0015 in, 0.002 in and 0.003 in. If your drawing uses ISO 286 fit designations, send the fit class (for example H7 on the bore) and we will machine to that instead.
- Close running clearances are normally finished after fitting. A sleeve pressed into a housing will close in slightly; if the final clearance is critical, specify finish machining after installation, or ask us to allow for the press fit when sizing the bore.
Casting method and what it changes
| Method | EN suffix | Characteristics | Typical use |
|---|---|---|---|
| Continuous cast | GC | Fine grain, low porosity, lead evenly distributed | Standard sleeve sizes from bar stock |
| Centrifugal cast | GZ | Dense outer wall, sound structure | Larger diameters and thicker walls |
| Sand cast | GS | Risk of lead segregation; lower strength | One-off or very large sections |
For bearing duty, continuous and centrifugal stock are preferred. Sand castings can show local lead segregation, which lowers strength in the affected area. See casting bronze bushings for more on the process selection.
Lubrication options
Oil grooves and holes
Standard sleeves rely on external lubricant delivered through the housing. Grooves cut into the bore — straight, helical, figure-eight or circumferential — distribute oil or grease along the contact length. Grooves reduce the effective bearing area, so they are sized against contact pressure rather than added as a default. Helical and figure-eight patterns suit rotating shafts; straight axial grooves suit oscillating motion.
Graphite-plugged sleeves
Where relubrication is impractical, graphite plugs are embedded through the wall in a pattern covering roughly 20–30% of the bearing area. As the sleeve wears, graphite transfers to the shaft and forms a solid film, so the assembly runs without grease. This suits low-speed, oscillating or inaccessible locations, and it suits industries where oil leakage is a problem, such as food processing and textiles.
Choosing between them
| Condition | Recommended option |
|---|---|
| Regular relubrication is possible | Plain sleeve with grooves |
| High speed with ample oil supply | Plain sleeve with grooves |
| No access for relubrication | Graphite-plugged sleeve |
| Low speed or oscillating motion | Graphite-plugged sleeve |
| Product must stay free of oil | Graphite-plugged sleeve |
| Temperature above oil limits | Graphite-plugged sleeve |
Typical applications
- Agricultural equipment — pivot points and linkages on tractors and harvesters, where dirt ingestion and intermittent lubrication are the norm.
- Hydraulic pumps and motors — gear and vane pump bodies, where the lead phase tolerates brief boundary lubrication.
- Construction and mining — excavator boom and loader linkage points under impact load.
- Industrial machinery — press guides, conveyor rollers, injection molding machine linkages.
- Gearboxes and reducers — shafts running at moderate speed with oil bath lubrication.
C93200 is not the right choice for continuously submerged seawater service or for acidic duty; in those environments an aluminum bronze or a nickel aluminum bronze performs better. See aluminum bronze sleeve bushings.
How to order
Send as much of the following as you have. The first three are usually enough for a quotation:
- Inner diameter, outer diameter and length, in millimetres, plus the fit class if one is specified.
- Quantity, and whether this is a one-off or a repeat item.
- Lubrication arrangement: plain, grooved, or graphite-plugged.
- Shaft material and hardness, surface finish and the running clearance you need.
- Load, speed and whether motion is continuous, oscillating or intermittent.
- Operating temperature and environment, including any compliance requirement such as lead-free.
- A drawing (DXF, DWG or PDF) or a sample of the existing part.
Parts are shipped from our own plant. Tell us the Incoterms you work to and we will quote accordingly. Related: CNC machining of bronze.
Frequently asked questions
What is the difference between a metric sleeve and an inch sleeve?
Only the dimension standard. The alloy, the casting method and the machining route are the same. Metric sleeves are made to millimetre dimensions for equipment built to ISO or DIN drawings; inch sleeves suit SAE dimensioning. We hold both ranges — see cast bronze inch sleeves.
Can I get sizes outside the 2 mm to 100 mm ID range?
Yes. That range covers our standard stock; anything outside it is machined to drawing, which affects lead time rather than feasibility.
Is C93200 the same as SAE 660?
Yes. SAE 660 is the older automotive designation for the same alloy now carried as UNS C93200. European drawings will call it CuSn7Zn4Pb7-C or CC493K.
Do graphite-plugged sleeves still need grease?
No. The graphite supplies the lubrication. Grease is not applied, and in dusty environments it tends to hold abrasive particles.
What temperature can C93200 run at?
Design for a maximum of 230 °C continuous operation. This is a property of the alloy, not of the lubrication; check the limit of your oil or grease separately, since that is often lower.
Is C93200 RoHS compliant?
No. It contains 6–8% lead and is restricted under RoHS and REACH. If you need a lead-free part, ask us about aluminum bronze, manganese bronze or ECO bronze alternatives.
Get a quotation
Send the dimensions, quantity and lubrication requirement and we will come back with a recommendation and a price. Drawings in DXF, DWG or PDF are all workable, as is a sample of the part you are replacing.
Email: una@viiplus.com
