Brass CNC Machining
Outstanding machinability, brilliant surfaces — the king of machining.
Brass — The King of Machining
Brass (copper-zinc alloy) is considered one of the most machinable materials of all. The alloy CuZn39Pb3 (free-machining brass) is the reference material for machinability — it defines the machinability rating of 100% against which all other copper alloys are measured.
Brass excels through: excellent chip breaking, extremely smooth surfaces directly from the machine, good corrosion resistance, and an attractive golden appearance.
Brass Grades for CNC Machining
| Alloy | Composition | Suitability |
|---|---|---|
| CuZn39Pb3 | Cu 58%, Zn 39%, Pb 3% | Free-machining brass, perfect for turned parts |
| CuZn37 | Cu 63%, Zn 37% | Cold-formable, good appearance, for milled parts |
| CuZn36Pb3 | Cu 61%, Zn 36%, Pb 3% | Good balance of strength and machinability |
Pro tip: For serial turned parts, always use CuZn39Pb3 — the lead additives ensure perfect chip breaking and minimal tool wear.
Cutting Data and Special Characteristics
- Cutting speed: 200–400 m/min (milling), 250–500 m/min (turning) — significantly faster than steel
- Tools: Uncoated solid carbide end mills often suffice. Prefer sharp geometries
- Coolant: Dry machining or MQL often possible — brass generates little heat
- Surfaces: Ra 0.4 achievable directly from the machine, without post-processing
Brass cannot be hardened (unlike steel). Strength is controlled through alloying and cold working.
Typical Applications
- Electrical Engineering — Connectors, terminals, contacts (good conductivity)
- Plumbing & Fittings — Valves, fittings, taps (drinking water safe)
- Watches & Jewelry — Cases, dials, gears (golden appearance)
- Mechanical Engineering — Sliding elements, bushings, guides (good sliding properties)
- Musical Instruments — Mouthpieces, valves, keys
Frequently asked Questions
Why is brass so easy to machine?
Leaded brass (CuZn39Pb3) forms short, crumbly chips instead of long continuous chips. The lead acts as a natural lubricant at the cutting edge and drastically improves chip breaking. This enables the highest cutting speeds.
Can brass be polished?
Yes — brass can be excellently polished mechanically and chemically. Ra values of 0.05 µm (mirror finish) are possible. However, untreated brass tarnishes over time — a clear lacquer coating can prevent this.
Is brass magnetic?
No — brass is non-magnetic. This makes it ideal for applications in metrology, electronics, and wherever magnetic neutrality is required.
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