Brass and copper CNC machining

We machine brass and copper by CNC turning and CNC milling. Brass and copper sheet parts are cut and bent through our sheet metal services. The exact alloy is confirmed in your quote.

Copper alloys are named by UNS number, kept by the Copper Development Association (CDA). Coppers run from C10100 to C15999, and brasses from C20000 to C49999. C2xxxx alloys are copper-zinc brasses, and C3xxxx are leaded brasses made for easier machining (CDA).

Free-cutting brass is the benchmark: CDA rates C36000 at 100 on its machinability scale, and rates every other copper alloy against it (CDA). Pure copper is far harder to cut, and a free-machining copper sits between the two.

Ratings and conductivity are from CDA (C36000, C26000, C14500, C11000, UNS coppers). IACS is the International Annealed Copper Standard, the usual scale for conductivity. Example alloys are labels, not a list of what we stock.

The lead in leaded brasses acts as a chip breaker and a lubricant at the tool (CDA). Chips break into small pieces instead of long strings, so the tool can run fast and leave a clean surface. That’s why free-cutting brass is a common choice for turned fittings and threaded parts.

Pure copper has no chip breaker, so it cuts with long, tough chips and a slower cycle. That shows up in its CDA rating of 20, against 100 for free-cutting brass (CDA).

What that means for your part:

• Turned parts with many features: C36000 brass, if lead is acceptable.
• Parts that carry current with many features: a free-machining copper such as C14500 keeps most of copper’s conductivity and machines far better than C11000.
• Simple busbars and plates: C11000, where conductivity matters more than machining time.
• Formed and machined parts: a C2xxxx brass such as C26000, which cold works well (CDA).

It depends on the market and the use. In the US, parts that touch drinking water must be “lead free” under the Safe Drinking Water Act, which means a weighted average of no more than 0.25% lead across the wetted surfaces (US EPA). Free-cutting brass such as C36000 contains several percent lead, well above that limit (CDA).

In the EU, the RoHS Directive has an exemption, 6(c), that allows lead as an alloying element in copper alloys up to 4% by weight (EUR-Lex). Exemptions are reviewed over time, so check the current status for your product.

If your part needs lead-free brass, say so on the drawing, and we confirm a suitable alloy in the quote.

Brass and copper are often left as-machined for their natural color, or plated. Nickel and chrome plating on copper alloys is specified to ASTM B456 by service grade (ASTM International).

Our full list of finishes:

• As-machined
• Bead blasting
• Anodizing Type II
• Anodizing Type III (hard anodizing)
• Powder coating
• Brushing
• Passivation
• Electroplating (nickel, chrome, zinc)
• Painting

Write the UNS number, the temper and the product standard if one applies. For example (an example callout, not a recommendation): “Brass C36000, H02 half hard, rod to ASTM B16”. ASTM B187 covers copper bar and busbar, and ASTM B124 covers forging rod and bar (ASTM International).

What to put on the drawing or in your message:

1. UNS number, such as C36000 or C11000. “Brass” or “copper” alone isn’t enough to quote.
2. Temper, such as H02 half hard, if it matters for the part.
3. Lead limits, if the part touches drinking water or must meet RoHS without the exemption.
4. Finish, with the plating standard and any contact faces to mask.

Every order comes with a mill certificate that traces the metal to its batch, along with QC inspection and ISO 9001 documentation.

• Standard QC inspection
• Material certification (mill certs)
• ISO 9001 documentation