Brass 360 Free Machining
Comprehensive technical specification for Brass 360 (C36000) free-machining brass, covering Canadian stock sizing, machinability, tooling, defects, and handling guidelines for fabrication and machining operations.
Material Overview & Common Uses
Brass 360 (UNS C36000) is the industry standard for free-machining brass, containing nominally 61.5% copper, 35.5% zinc, and 3% lead. The lead content acts as a chip breaker and lubricant, enabling high-speed machining with excellent surface finish. It is the most machinable of all copper alloys, rated at 100% machinability relative to free-cutting brass. Common applications include high-volume screw machine parts, fittings, valves, gears, pinions, plumbing components, and decorative hardware. In Canadian fabrication shops, it is frequently used for custom CNC turned parts, architectural trim, and marine hardware due to its corrosion resistance and ease of finishing.
Core Technical Properties & Sizing
| Property | Value |
|---|---|
| Density | 0.307 lb/in³ (8.50 g/cm³) |
| Tensile Strength | 58,000 psi (400 MPa) typical for half-hard temper |
| Yield Strength (0.5% offset) | 45,000 psi (310 MPa) |
| Elongation | 18% in 2 inches |
| Hardness | Rockwell B78 (typical half-hard) |
| Modulus of Elasticity | 14,000 ksi (97 GPa) |
| Thermal Conductivity | 67 Btu/ft·hr·°F (116 W/m·K) |
| Electrical Conductivity | 26% IACS |
| Melting Range | 1,630–1,710°F (888–932°C) |
Standard Canadian Stock Sizes:
| Form | Size Range | Length |
|---|---|---|
| Round bar | 1/8″ to 6″ diameter | 12′ random lengths |
| Hex bar | 1/4″ to 2″ across flats | 12′ lengths |
| Square bar | 1/4″ to 2″ | 12′ lengths |
| Rectangular bar | 1/8″ × 1/2″ up to 1″ × 6″ | 12′ lengths |
| Sheet/plate | 0.020″ to 0.125″ thick, 48″ × 96″ or 48″ × 120″ | Sheet sizes |
| Tube | 1/8″ to 2″ OD, various walls | 12′ lengths |
Tolerances (ASTM B16/B16M):
| Form | Size Range | Tolerance |
|---|---|---|
| Round bar | Up to 1/2″ | ±0.002″ |
| Round bar | 1/2″ to 1″ | ±0.003″ |
| Round bar | 1″ to 2″ | ±0.005″ |
| Hex bar (across flats) | Up to 1″ | ±0.004″ |
| Hex bar (across flats) | 1″ to 2″ | ±0.006″ |
| Sheet/plate thickness | 0.020″–0.064″ | ±0.002″ |
| Sheet/plate thickness | 0.065″–0.125″ | ±0.003″ |
| Sheet/plate length/width | All | ±1/8″ |
Temper options: H02 (half-hard) most common for machining; O60 (soft annealed) for severe forming; H04 (hard) for wear resistance.
Machinability, Tooling & Feeds
Brass 360 is rated 100% machinability (highest of all brasses). It produces short, broken chips and requires no chip breaker geometry.
| Operation / Tooling | Speed (SFM) | Feed (IPR) | Depth of Cut | Notes |
|---|---|---|---|---|
| Turning (HSS) | 300–600 | 0.005–0.015 | 0.050–0.150″ | Use M2 or M42; flood coolant recommended |
| Turning (Carbide, C2) | 600–1200 | 0.008–0.025 | 0.050–0.150″ | For high production; no chip breaker needed |
| Drilling | 200–400 | 0.003–0.010 | — | Standard HSS twist drills; flood coolant |
| Tapping | 30–50 | — | — | Use spiral point taps; 30–50 SFM |
Coolant: flood coolant recommended for high production; mist or dry acceptable for light cuts. Surface finish achievable: 16–32 microinches Ra with sharp tooling. Note: lead content requires proper ventilation and chip handling per WHMIS/GHS regulations.
Common Defects & Quality Control
| Defect | Description | Acceptance Criteria |
|---|---|---|
| Surface cracks / seams | Fine lines along bar length from extrusion or drawing | Reject if depth exceeds 0.005″ or visible after machining |
| Porosity / gas holes | Typically in center of bar; causes tool chatter and poor finish | Check by sectioning sample; reject if present |
| Lead segregation | Uneven lead distribution leads to inconsistent machinability | Suspect if tool wear varies across bar; section to verify |
| Burrs | Excessive burrs indicate dull tooling or incorrect geometry | Acceptable if <0.005″ height |
| Dimensional variation | Out-of-round or out-of-hex beyond ASTM tolerances | Measure with micrometer at three points along length; reject if outside tolerance |
| Surface oxidation / discoloration | Dark spots or tarnish | Acceptable if not pitted; can be removed with citric acid passivation |
QC checks: verify hardness (Rockwell B) on incoming stock; perform tensile test on first article; check dimensions per ASTM B16; visual inspection for cracks/seams. Reject material if any defect exceeds 10% of cross-section or if tensile strength is below 55 ksi.
Storage, Handling & Racking Guidelines
Store Brass 360 indoors in a dry, climate-controlled environment (40–80°F, <60% RH). Avoid direct contact with moisture to prevent tarnish. Rack round bars horizontally on cantilever racks with padded supports to prevent scratching; maximum unsupported span 4 feet for bars up to 1″ diameter, 6 feet for larger. Hex and square bars can be stacked in bins or on pallet racks with dividers. Sheet/plate should be stored flat on wooden pallets, interleaved with kraft paper or plastic film to prevent scratching. Do not store near carbon steel or iron to avoid galvanic corrosion from dust. Use dedicated brass storage area or separate with plastic sheeting. Handling: use clean gloves to avoid oil and dirt; lift bars with slings or padded clamps; never drop or drag. FIFO rotation recommended; label each bundle with alloy, temper, size, and heat number. Shelf life: indefinite if stored properly; but tarnish may require chemical cleaning before use.