Copper alloys are niche but critical — electrical connectors need conductivity, valve stems need beryllium copper's strength. The surprise for most people: brass is the easiest metal to machine, period. This page covers when to use which copper alloy.
| Your Situation | Use This | Why |
|---|---|---|
| High-volume machined parts, fittings, valves | C36000 brass | Best machinability of any metal. 100% machinability rating. Cuts like butter. |
| Electrical connectors, bus bars | C11000 copper | Highest conductivity (101% IACS). But gummy to machine. |
| Need spring properties + conductivity | C17200 beryllium copper | BeCu can reach HRC 40 with conductivity. Valve seats, relay contacts, spring contacts. |
| Decorative / architectural hardware | C26000 (cartridge brass) | Good formability + gold-like appearance. Doorknobs, hinges. |
| Marine hardware | C46400 naval brass | Good corrosion resistance. Propeller shafts, marine fittings. |
| Property | C36000 Brass | C11000 Copper | C17200 BeCu |
|---|---|---|---|
| Type | Free-machining brass | ETP copper | Beryllium copper |
| Tensile (MPa) | 360 | 220 | 1200 (aged) |
| Yield (MPa) | 250 | 70 | 1100 (aged) |
| Density (g/cm³) | 8.50 | 8.96 | 8.25 |
| Conductivity (%IACS) | 26% | 101% | 20–30% (aged) |
| Machinability | 100% (best) | 20% (gummy) | 50% (before age) |
| Hardness | 78 HB | 45 HB | 38 HRC (aged) |
| Relative cost | 1.0x | 1.2–1.5x | 5–8x |
If you need to machine thousands of parts fast, C36000 brass is your material. It has the highest machinability rating of any metal (100% on the scale where free-machining steel is ~70%). Chip breaking is excellent, tool life is measured in thousands of parts, and surface finish is naturally smooth.
The lead content (2.5–3.5%) creates the free-machining characteristics. This also means it cannot be welded or used in potable water systems.
| Mistake | What happens | Correct approach |
|---|---|---|
| Using C11000 for machined fittings | Terrible machinability, gummy chips, tool wear is 5x brass | For machined parts use C36000 brass |
| Using C36000 for electrical bus bars | Only 26% IACS conductivity — huge resistance | Use C11000 for electrical applications |
| Not age-hardening C17200 | Only 50% of its potential strength | Machine in solution-treated state, then age at 320°C for 2-3 hours |
| High cutting speed on brass | Buildup on tool, poor finish | Brass needs moderate speed (100-200 m/min) with high feed |