Bronze 932 (SAE 660) Bearing Bronze – Technical Material Specification
Complete technical specification for Bronze 932 (SAE 660) high-leaded tin bronze, covering properties, Canadian stock sizing, machinability, defects, and handling for industrial bearing and bushing applications.
Material Overview & Common Uses
Bronze 932, also known as SAE 660 or C93200, is a high-leaded tin bronze alloy widely used in Canadian industrial shops for bearings, bushings, wear plates, and thrust washers. Its composition (nominally 83% Cu, 7% Sn, 7% Pb, 3% Zn) provides excellent embeddability for contaminants, good conformability, and moderate strength. Common applications include general-purpose sleeve bearings, pump bushings, machine tool slides, and slow-speed, high-load pivot points.
It is the go-to material for non-lubricated or marginally lubricated sliding contact in sawmill equipment, mining machinery, and hydraulic systems across Canada.
Core Technical Properties & Sizing
| Property | Value |
|---|---|
| Density | 0.322 lb/in³ (8.91 g/cm³) |
| Tensile Strength | 35,000 psi (241 MPa) minimum |
| Yield Strength (0.5% offset) | 18,000 psi (124 MPa) typical |
| Elongation in 2 in | 12% minimum |
| Brinell Hardness (500 kg load, 10 mm ball) | 65–75 typical |
| Machinability Rating | 70% (relative to free-cutting brass = 100%) |
| Melting Range | 1790–1900°F (977–1038°C) |
| Thermal Conductivity | 33.6 BTU·in/(hr·ft²·°F) at 68°F |
| Electrical Conductivity | 12% IACS at 68°F |
| Modulus of Elasticity | 14,500 ksi (100 GPa) |
| Poisson's Ratio | 0.33 |
Canadian Common Stock Sizes (nominal, inches):
| Form | Available Sizes |
|---|---|
| Round Rod | 1/4, 3/8, 1/2, 5/8, 3/4, 7/8, 1, 1-1/4, 1-1/2, 1-3/4, 2, 2-1/2, 3, 3-1/2, 4, 5, 6, 8, 10, 12 |
| Hex Bar | 1/2, 5/8, 3/4, 7/8, 1, 1-1/4, 1-1/2, 1-3/4, 2, 2-1/2, 3 |
| Square Bar | 1/2, 3/4, 1, 1-1/4, 1-1/2, 2, 2-1/2, 3, 4 |
| Plate/Sheet (thickness) | 1/8, 3/16, 1/4, 3/8, 1/2, 3/4, 1, 1-1/4, 1-1/2, 2, 2-1/2, 3 |
| Plate/Sheet (width x length) | 12 x 12, 12 x 24, 24 x 24, 24 x 48, 36 x 36, 36 x 48, 48 x 48, 48 x 96 |
| Tube (OD x ID) | 1 x 1/2, 1-1/4 x 3/4, 1-1/2 x 1, 2 x 1, 2 x 1-1/2, 2-1/2 x 1-1/2, 3 x 2, 4 x 3, 5 x 4, 6 x 5 |
Tolerances (ASTM B505 / B271):
| Dimension / Feature | Size Range | Tolerance |
|---|---|---|
| Rod/Bar Diameter | Up to 1 in | ±0.005 in |
| 1–4 in | ±0.010 in | |
| Over 4 in | ±0.015 in | |
| Plate Thickness | Up to 1/2 in | ±0.010 in |
| 1/2–1 in | ±0.015 in | |
| Over 1 in | ±0.020 in | |
| Tube OD | Up to 3 in | ±0.010 in |
| 3–6 in | ±0.015 in | |
| Tube ID | Up to 2 in | ±0.010 in |
| 2–4 in | ±0.015 in | |
| Over 4 in | ±0.020 in | |
| Length (cut-to-size) | Up to 12 in | ±1/16 in |
| Longer | ±1/8 in | |
| Straightness | Rod/Bar up to 2 in dia | 1/16 in per 3 ft |
| Rod/Bar larger | 1/8 in per 3 ft |
Machinability, Tooling & Feeds
Bronze 932 has a machinability rating of 70 (free-cutting brass = 100). It produces short, broken chips and is generally easy to machine with carbide tooling.
| Parameter / Operation | Recommendation |
|---|---|
| Machinability Rating | 70% (free-cutting brass = 100%) |
| Tooling (Turning/Boring) | Uncoated or TiN-coated carbide inserts (C2 grade) |
| Tooling (Drilling/Tapping) | High-speed steel (M2 or M42) |
| Surface Speed (Turning) | 400–600 SFM |
| Feed (Turning) | 0.005–0.015 in/rev |
| Depth of Cut (Turning) | 0.020–0.150 in |
| Speed (Drilling) | 200–300 SFM |
| Feed (Drilling) | 0.003–0.008 in/rev |
| Coolant | Water-soluble oil or straight oil recommended; dry roughing acceptable |
| Reaming Stock | 0.005–0.010 in |
| Tapping | Spiral point taps; pre-drill 75% thread depth |
| Grinding | Silicon carbide wheels; light passes; flood coolant |
| Sawing (Band) | 4–6 teeth per inch; blade speed 100–200 SFM |
| Deburring | Fine files or abrasive pads (lead content softens edges) |
Common Defects & Quality Control
| Defect | Description | QC Check |
|---|---|---|
| Porosity | Gas holes or shrinkage cavities, especially in larger sections; visible as pinholes or spongy areas | Visual inspection; max 5% area per ASTM B505 (2% for pressure-tight) |
| Lead Segregation | Lead-rich spots or streaks causing soft, smeary patches and inconsistent hardness | Hardness test (Brinell 65–75) |
| Inclusions | Dross, sand, or oxide particles embedded in the casting | Monitor for tool chatter and poor surface finish |
| Cracks | Hot tears or stress cracks from rapid cooling; fine lines near edges | Visual inspection; dye penetrant testing for critical applications |
| Dimensional Variation | Out-of-round, oversize, or undersize due to mold shift or shrinkage | Micrometers and bore gauges |
| Surface Scale | Heavy oxide layer from casting process | Ensure removal before final machining |
Storage, Handling & Racking Guidelines
- Store Bronze 932 indoors in a dry, clean environment. Avoid direct contact with moisture to prevent tarnishing and surface oxidation.
- Rack round rods horizontally on padded supports spaced 3–4 ft apart to prevent bending.
- Stack plates flat on wooden pallets with slip sheets between layers to avoid scratching.
- Do not store near acids, ammonia, or sulfur compounds (corrosive).
- For long-term storage, apply a light rust-preventive oil or wrap in VCI paper.
- Handle with clean gloves to avoid oil and dirt contamination.
- Use lifting straps or padded clamps for heavy bars and plates; never drop or drag.
- Keep stock organized by size and heat number for traceability.
- Rotate inventory FIFO to avoid age-hardening effects (minimal in this alloy, but good practice).
- For cut pieces, deburr edges immediately and store in labeled bins or racks.