Brass CNC machining describes a process in which a brass workpiece is shaped by a computer-controlled cutting tool. The process begins when a designer creates a digital model in CAD software. The software then converts that model into G-code, a set of instructions that guides the CNC machine. Every movement of the cutting tool—whether it bores, mills, or turns—follows the G-code.
In this guide, we will explain what brass CNC machining involves, and help you pick the right alloy for your next project.
Why Choose Brass for CNC Machining?
Brass offers several benefits for precision parts:
- Easy to Cut. Many brass grades feed smoothly through mills and lathes.
- Good Wear Resistance. The alloys can last under friction.
- Attractive Finish. Machined brass has a warm gold color that can shine or patina.
- Corrosion Resistance. Some grades stand up well to moisture or mild acids.
- Stable Dimensions. Brass parts stay true to size after machining.
Because of these traits, industries from plumbing to electronics use brass for fittings, connectors, gears, and decorative hardware.
How to Read Brass Grade Designations
Most brass alloys in North America use a “C” code followed by a number (for example, C36000). The first digit (2, 3, 4, or 7) groups the alloys by copper-to-zinc ratio and special additions:
- C20000 series: High-copper “alpha” brasses (up to 99% copper).
- C30000 series: Balanced “alpha-beta” brasses (60–70% copper).
- C40000 series: Higher-zinc “beta” brasses (55–63% copper).
- C77000 series: Nickel-silver alloys (copper, nickel, zinc).
How Brass Grades Are Classified
Brass alloys fall into three main categories based on their microstructure and zinc content:
- Alpha Brasses (up to 37% zinc)
- Alpha-Beta (Duplex) Brasses (around 35–45% zinc)
- Beta Brasses (above 45% zinc)
Below, we group the eighteen grades into three broad categories: alpha brasses (high copper), alpha‑beta brasses (intermediate zinc), and beta brasses (high zinc).
Alpha Brasses (C200 Series)
Alpha brasses contain more than 65% copper. Those alloys stay soft and easy to shape at room temperature. They also resist corrosion better than higher‑zinc brasses.
C210 – Gilding Metal
C210 has a deep reddish color and high ductility. Manufacturers use it for decorative items and cold‑formed shapes. The material bends easily without cracking, so it suits jewelry, medals, and plumbing trim.
Composition: 95% copper, 5% zinc, plus trace lead and other elements
Key Properties:
- Deep red color
- Exceptional cold-work formability
- Moderate strength
| Property | Value |
|---|---|
| Density | 8.90 g/cm³ |
| Melting Point | 925–960°C (1700–1760°F) |
| Tensile Strength | 280–455 MPa (40,600–66,000 psi) |
| Yield Strength | 70–340 MPa (10,150–49,300 psi) |
| Elongation | 30–60% |
| Hardness (Brinell) | 60–130 BHN |
| Electrical Conductivity | 37% IACS (International Annealed Copper Standard) |
C220 – Commercial Bronze
C220 offers a gold‑tone finish and moderate strength. Engineers select it for stamped parts, connectors, and heat exchanger tubes. The alloy resists corrosion in mild environments, and it holds up under light mechanical loads.
Composition: 90% copper, 10% zinc, with traces of lead and iron
Key Properties:
- Balanced strength and formability
- Good corrosion resistance
| Property | Value |
|---|---|
| Density | 8.80 g/cm³ |
| Melting Point | 920–950°C (1690–1740°F) |
| Tensile Strength | 315–520 MPa (45,700–75,400 psi) |
| Yield Strength | 100–345 MPa (14,500–50,000 psi) |
| Elongation | 25–55% |
| Hardness (Brinell) | 70–150 BHN |
| Electrical Conductivity | 34% IACS (International Annealed Copper Standard) |
C230 – Red Brass
C230 blends strong corrosion resistance with good formability. It finds use in plumbing fittings, radiator cores, and valves. Designers value its balance of toughness and workability.
Composition: 85% copper, 15% zinc, with trace elements
Key Properties:
- High corrosion resistance
- Good formability
| Property | Value |
|---|---|
| Density | 8.71 g/cm³ |
| Melting Point | 915–940°C (1680–1725°F) |
| Tensile Strength | 300–550 MPa (43,500–79,800 psi) |
| Yield Strength | 70–310 MPa (10,150–45,000 psi) |
| Elongation | 20–60% |
| Hardness (Brinell) | 60–140 BHN |
| Electrical Conductivity | 28% IACS (International Annealed Copper Standard) |
C260 – Cartridge Brass
C260 ranks among the most versatile alpha brasses. It has bright yellow color, good strength, and excellent cold‑forming traits. The alloy often appears in ammunition casings, architectural trim, and precision components.
Composition: 70% copper, 30% zinc, trace lead
Key Properties:
- Good balance of strength and ductility
- Pleasant golden color
| Property | Value |
|---|---|
| Density | 8.53 g/cm³ |
| Melting Point | 930–965°C (1710–1770°F) |
| Tensile Strength | 310–620 MPa (45,000–90,000 psi) |
| Yield Strength | 90–370 MPa (13,000–53,700 psi) |
| Elongation | 15–45% |
| Hardness (Brinell) | 80–160 BHN |
| Electrical Conductivity | 28% IACS (International Annealed Copper Standard) |
C272 – Yellow Brass
C272 displays strong corrosion resistance and easy drawing. Manufacturers employ it for electrical hardware, fasteners, and decorative hardware. The alloy machines cleanly and polishes well.
Composition: 63% copper, 37% zinc, trace lead
Key Properties:
- High strength among alpha brasses
- Good machinability with lead
| Property | Value |
|---|---|
| Density | 8.48 g/cm³ |
| Melting Point | 905–935°C (1660–1715°F) |
| Tensile Strength | 315–585 MPa (45,700–84,800 psi) |
| Yield Strength | 100–360 MPa (14,500–52,200 psi) |
| Elongation | 15–45% |
| Hardness (Brinell) | 90–165 BHN |
| Electrical Conductivity | 28% IACS (International Annealed Copper Standard) |
C274 – Yellow Brass Variation
C274 shares many traits with C272, but it often contains slightly different trace elements. Fabricators use it interchangeably with C272 when they want a bright yellow finish and good machinability.
Composition: 62% copper, 38% zinc, trace lead
Key Properties:
- Similar to C27200 but with slightly more zinc
- A bit harder and stronger
| Property | Value |
|---|---|
| Density | 8.47 g/cm³ |
| Melting Point | 900–940°C (1650–1725°F) |
| Tensile Strength | 310–575 MPa (45,000–83,400 psi) |
| Yield Strength | 90–355 MPa (13,050–51,500 psi) |
| Elongation | 20–45% |
| Hardness (Brinell) | 85–160 BHN |
| Electrical Conductivity | 27% IACS (International Annealed Copper Standard) |
Alpha‑Beta Brasses (C300 Series)
Alpha‑beta brasses contain roughly 60–65% copper and 35–40% zinc. They combine the ductility of alpha brasses with the strength of beta brasses, and they respond well to both cold and hot working.
C360 – Free‑Machining Brass
C360 leads the industry in machining speed and finish quality. The added lead forms microscopic chips during cutting, reducing tool wear. Manufacturers choose C360 for complex parts that demand tight tolerances, such as fittings, gears, and valve components.
Composition: 61% copper, 35% zinc, 3% lead
Key Properties:
- Exceptional machinability
- Moderate strength
| Property | Value |
|---|---|
| Density | 8.47 g/cm³ |
| Melting Point | 930–935°C (1710–1715°F) |
| Tensile Strength | 370–470 MPa (53,700–68,100 psi) |
| Yield Strength | 210–320 MPa (30,500–46,400 psi) |
| Elongation | 12–25% |
| Hardness (Brinell) | 100–160 BHN |
| Electrical Conductivity | 26% IACS (International Annealed Copper Standard) |
C314 – Leaded Commercial Bronze
C314 offers fair strength along with improved machinability from its 2% lead. Shops use it for high‑volume turned and milled parts that do not require extreme corrosion resistance.
Composition: 89% copper, 9% zinc, 2% lead
Key Properties:
- Good machinability with less zinc
- High elongation for shaping
| Property | Value |
|---|---|
| Density | 8.77 g/cm³ |
| Melting Point Range | 910–945°C (1670–1735°F) |
| Tensile Strength | 295–515 MPa (42,800–74,700 psi) |
| Yield Strength | 80–325 MPa (11,600–47,100 psi) |
| Elongation | 20–60% |
| Hardness (Brinell) | 65–140 BHN |
| Electrical Conductivity | 33% IACS (International Annealed Copper Standard) |
C330 – Low‑Leaded Brass
C330 balances lead content to meet regulations in plumbing and food‑service hardware. It machines well and retains good ductility for forming operations.
Composition: 65% copper, 34% zinc, 1% lead
Key Properties:
- Fair machinability
- Improved ductility over high-lead grades
| Property | Value |
|---|---|
| Density | 8.49 g/cm³ |
| Melting Point Range | 900–950°C (1650–1740°F) |
| Tensile Strength | 300–570 MPa (43,500–82,700 psi) |
| Yield Strength | 90–350 MPa (13,050–50,750 psi) |
| Elongation | 10–50% |
| Hardness (Brinell) | 75–160 BHN |
| Electrical Conductivity | 27% IACS (International Annealed Copper Standard) |
C335 – Free‑Machining Alloy
C335 closely mirrors C360 but with slightly less lead. Fabricators pick C335 when they want free‑cutting behavior with reduced environmental concerns about lead content.
Composition: 62.5% copper, 36.5% zinc, 1% lead
Key Properties:
- Good compromise of machinability and strength
- Balanced cost-to-performance
| Property | Value |
|---|---|
| Density | 8.45 g/cm³ |
| Melting Point Range | 895-955°C (1640-1750°F) |
| Tensile Strength | 290-560 MPa (42,000-81,200 psi) |
| Yield Strength | 85-345 MPa (12,300-50,000 psi) |
| Elongation | 12-45% |
| Hardness (Brinell) | 70-155 BHN |
| Electrical Conductivity | 26% IACS (International Annealed Copper Standard) |
C353– High‑Leaded Brass
C353 increases lead beyond C330 levels to maximize machinability in heavy‑duty cutting. Shops employ it for intricate parts where cycle times matter most.
Composition: 62% copper, 35.5% zinc, 2.5% lead
Key Properties:
- Superior machinability among leaded alloys
- Best surface finish under high-speed tooling
| Property | Value |
|---|---|
| Density | 8.44 g/cm³ |
| Melting Point Range | 890-950°C (1635-1740°F) |
| Tensile Strength | 285-550 MPa (41,300-79,800 psi) |
| Yield Strength | 80-340 MPa (11,600-49,300 psi) |
| Elongation | 10-40% |
| Hardness (Brinell) | 65-150 BHN |
| Electrical Conductivity | 25% IACS (International Annealed Copper Standard) |
C365 – Leaded Muntz Metal
C365 resembles classic Muntz metal but with added lead. The alloy forges and machines easily, making it a solid choice for both castings and machined components.
Composition: 59% copper, 39% zinc, 2% lead
Key Properties:
- Good machinability with moderate strength
- Decent forging and machining balance
| Property | Value |
|---|---|
| Density | 8.41 g/cm³ |
| Melting Point Range | 885-955°C (1625-1750°F) |
| Tensile Strength | 280-540 MPa (40,600-78,300 psi) |
| Yield Strength | 75-335 MPa (10,900-48,600 psi) |
| Elongation | 8-35% |
| Hardness (Brinell) | 60-145 BHN |
| Electrical Conductivity | 24% IACS (International Annealed Copper Standard) |
C37700 – Forging Brass
C377 suits hot‑forged parts, such as heavy fasteners and structural fittings. Brass suppliers recommend heating it above 800 °C before shaping.
- Composition: 58–61% copper, 37–40% zinc, 1–2.5% lead
- Key Properties:
- Excellent hot forging ability
- Good machining performance
| Property | Value |
|---|---|
| Density | 8.44 g/cm³ |
| Melting Point Range | 890-935°C (1635-1715°F) |
| Tensile Strength | 280-450 MPa (40,600-65,250 psi) |
| Yield Strength | 90-260 MPa (13,050-37,700 psi) |
| Elongation | 20-40% |
| Hardness (Brinell) | 65-110 BHN |
| Electrical Conductivity | 27% IACS (International Annealed Copper Standard) |
C38500 – Architectural Brass
C385 features extra lead for machinability but also meets decorative standards. Architects and designers specify it for door hardware, railings, and trim that require both precision and finish quality.
- Composition: 57% copper, 40% zinc, 3% lead
- Key Properties:
- High machinability with intentional lead boost
| Property | Value |
|---|---|
| Density | 8.40 g/cm³ |
| Melting Point Range | 880-955°C (1615-1750°F) |
| Tensile Strength | 275-530 MPa (39,900-76,900 psi) |
| Yield Strength | 70-330 MPa (10,150-47,900 psi) |
| Elongation | 6-30% |
| Hardness (Brinell) | 55-140 BHN |
| Electrical Conductivity | 23% IACS (International Annealed Copper Standard) |
Beta Brasses (C400 Series)
Beta brasses contain over 35% zinc. They remain strong but they require heating to form without cracking. They also exhibit lower corrosion resistance than alpha‑beta brasses.
C443 – Admiralty Brass
C443 adds arsenic for better seawater resistance without sacrificing strength. Shipbuilders use it for condenser tubes, pump parts, and valve bodies in marine applications.
Composition: 70% copper, 29% zinc, 0.02–0.06% arsenic
Key Properties:
- Excellent resistance to saltwater corrosion
- Moderate strength
| Property | Value |
|---|---|
| Density | 8.53 g/cm³ |
| Melting Point Range | 900-945°C (1650-1735°F) |
| Tensile Strength | 310-480 MPa (45,000-69,600 psi) |
| Yield Strength | 105-290 MPa (15,200-42,000 psi) |
| Elongation | 25-55% |
| Hardness (Brinell) | 80-120 BHN |
| Electrical Conductivity | 28% IACS (International Annealed Copper Standard) |
C464 – Naval Brass
C464 offers excellent performance in saltwater environments. Its tin boosts corrosion resistance and holds up in submerged service. Manufacturers rely on it for propeller shafts, hull fittings, and marine hardware.
Composition: 60% copper, 39.25% zinc, 0.75% tin
Key Properties:
- Outstanding corrosion resistance in marine settings
- Good ductility despite high zinc
| Property | Value |
|---|---|
| Density | 8.41 g/cm³ |
| Melting Point Range | 905-940°C (1660-1725°F) |
| Tensile Strength | 300-450 MPa (43,500-65,250 psi) |
| Yield Strength | 100-280 MPa (14,500-40,600 psi) |
| Elongation | 20-45% |
| Hardness (Brinell) | 75-115 BHN |
| Electrical Conductivity | 26% IACS (International Annealed Copper Standard) |
C485 – Leaded Naval Brass
C485 combines tin’s seawater protection with lead’s machinability. Shops choose it for complex marine parts that must meet fine machining tolerances.
Composition: 58.5% copper, 39% zinc, 1% tin, 1.5% lead
Key Properties:
- Combines marine corrosion resistance with better machinability
- Tin and lead together give balance of cut-ability and durability
| Property | Value |
|---|---|
| Density | 8.39 g/cm³ |
| Melting Point Range | 900-935°C (1650-1715°F) |
| Tensile Strength | 290-430 MPa (42,100-62,350 psi) |
| Yield Strength | 95-270 MPa (13,800-39,150 psi) |
| Elongation | 18-40% |
| Hardness (Brinell) | 70-110 BHN |
| Electrical Conductivity | 23% IACS (International Annealed Copper Standard) |
C770 – Nickel Silver
C770 does not contain lead. It substitutes nickel for both strength and corrosion resistance. Jewelers craft it into instruments and cutlery because it resists tarnish and polishes brightly.
Composition: 55–65% copper, 10–30% nickel, 18–27% zinc
Key Properties:
- High strength and wear resistance
- Attractive silver-like finish
| Property | Value |
|---|---|
| Density | 8.80 g/cm³ |
| Melting Point Range | 1000-1100°C (1832-2012°F) |
| Tensile Strength | 450-800 MPa (65,250-116,000 psi) |
| Yield Strength | 140-700 MPa (20,300-101,500 psi) |
| Elongation | 2-40% |
| Hardness (Brinell) | 130-240 BHN |
| Electrical Conductivity | 7% IACS (International Annealed Copper Standard) |
Comparing the 18 Brass Grades
| Grade | Copper % | Zinc % | Lead % | Machinability | Strength | Corrosion Resistance | Typical Use |
|---|---|---|---|---|---|---|---|
| C20000 | 95–99 | 1–5 | – | Fair | Low | Excellent | Plumbing, electrical, coins |
| C21000 | 95 | 5 | Trace | Fair | Low | Good | Jewelry, decorative |
| C22000 | 90 | 10 | Trace | Fair | Medium | Good | Fittings, castings |
| C23000 | 85 | 15 | Trace | Fair | Medium | Very good | Marine fittings, fasteners |
| C26000 | 70 | 30 | Trace | Good | Medium | Moderate | Cartridges, instruments |
| C27200 | 63 | 37 | Trace | Good | Medium | Good | Gears, bearings, screws |
| C27400 | 62 | 38 | Trace | Good | Medium-High | Good | Architectural trim, fittings |
| C36000 | 61 | 35 | 3 | Excellent | Medium | Fair | High-volume turned parts |
| C31400 | 89 | 9 | 2 | Very good | Medium | Good | Precision turned components |
| C33000 | 65 | 34 | 1 | Good | Medium | Good | Fasteners, small fittings |
| C33500 | 62.5 | 36.5 | 1 | Very good | Medium | Fair | Automotive, connectors |
| C35300 | 62 | 35.5 | 2.5 | Excellent | Medium | Fair | Shafts, fittings |
| C36500 | 59 | 39 | 2 | Very good | Medium | Fair | Trim, heat exchangers |
| C37700 | 58–61 | 37–40 | 1–2.5 | Very good | Medium | Good | Forged valve bodies |
| C38500 | 57 | 40 | 3 | Excellent | Medium | Fair | Decorative hardware |
| C44300 | 70 | 29 | Trace | Fair | Medium | Excellent (sea) | Marine fittings, condenser tubes |
| C46400 | 60 | 39.25 | Trace | Good | Medium | Outstanding (sea) | Ship components, sea applications |
| C48500 | 58.5 | 39 | 1.5 | Very good | Medium | Outstanding (sea) | Underwater fittings, hardware |
| C77000 | 55–65 | 18–27 | – | Good | High | Good | Instruments, decorative, cutlery |
How to Choose the Right Brass Grade
Choosing the best brass grade requires balancing several factors against your project’s demands:
- If you need fast CNC runs, go with C36000 or C35300. Their high lead content cuts down tool wear.
- For parts in wet or salty areas, choose C46400, C48500, or C44300. They resist rust from seawater.
- When you need to shape or bend parts before machining, select an alpha brass such as C21000 or C23000.
- If your part must carry electricity, pick a high‑copper grade like C20000 or C21000.
- For a nice surface finish, use C38500 or C77000. They polish to a bright, silver‑like shine.
- When cost matters, C26000 or C27200 often strike a good price‑to‑performance balance.
Always talk with your CNC shop about tool recommendations and cutting speeds. Even the easiest brass can cause issues if you push feed rates too high or try to remove too much metal in one pass.
Best Practices for Brass CNC Machining
Manufacturers can further improve outcomes by following these guidelines:
- Sharp carbide cutters and stable fixturing minimize chatter and tool wear.
- Adjust parameters to produce short, broken chips, which brass grades with lead content support best.
- Adequate flood coolant or mist lubrication prevents heat build-up and extends tool life.
- Clear chips promptly to avoid re-cutting and to ensure consistent surface finish.
- Measure key dimensions during the run to catch drift early, particularly for tight-tolerance parts.
Partnering with Your CNC Shop
Before you finalize your brass grade, confirm that your CNC machining services supplier has experience with your chosen alloy. Every brass type can behave differently under specific tooling, feeds, and speeds. At BOYI TECHNOLOGY, our team tests and optimizes cutting parameters for all common brass grades to deliver parts that meet tight tolerances and surface-finish requirements.
Ready to elevate your project with precision brass CNC machining—request your free consultation and quote today!
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Conclusion
Brass offers a wide range of CNC machining options, from soft, high-copper brasses to strong, beta-phase alloys and even nickel silvers. Each grade brings its own mix of machinability, strength, corrosion resistance, and appearance. By weighing your project’s needs—machining speed, environmental exposure, mechanical load, and finish requirements—you can select the perfect brass alloy.
FAQ
C36000 (Free‑Machining Brass) has the highest lead content (3 %) and is specifically designed for fast, precise CNC cutting with minimal tool wear.
Yes. C37700 (Forging Brass) is formulated for hot forging and still machines well, making it ideal for parts that start as forgings.
Yes. Low‑lead or lead‑free options like C33000 (1 % Pb) and some specialty naval brasses minimize lead content while retaining good machinability and corrosion resistance.
This article was written by engineers from the BOYI TECHNOLOGY team. Fuquan Chen is a professional engineer and technical expert with 20 years of experience in rapid prototyping, metal parts, and plastic parts manufacturing.
