Brass CNC
Machining

Brass is a copper-zinc alloy family that combines excellent machinability, good corrosion resistance, attractive appearance, and low friction properties. In CNC machining, brass is valued for its outstanding chip-breaking characteristics, ability to hold tight tolerances, and the bright, smooth surface finish it produces directly off the machine. Common applications include plumbing fittings, electrical connectors, valve bodies, precision instrument hardware, decorative components, and any part requiring a combination of corrosion resistance, conductivity, and high-quality aesthetics.

C360 (Free-Cutting Brass) and C260 (Cartridge Brass) differ in zinc content and the addition of lead. C360 contains approximately 61.5% copper, 35.5% zinc, and 3% lead — the lead dramatically improves machinability, making C360 the fastest-cutting brass available. C260 contains 70% copper and 30% zinc, with no lead — it has lower machinability than C360 but significantly better cold-forming ability, ductility, and is suitable for applications requiring RoHS compliance or potable water contact. For pure machining applications without regulatory constraints, C360 is preferred; for formed parts or lead-free specifications, C260 is the correct choice.

No. C360 brass contains approximately 3% lead, which is a restricted substance under the RoHS directive. C360 cannot be used in electrical or electronic equipment subject to RoHS regulations, nor in food-contact or potable water applications. For applications requiring lead-free brass, specify C260. We provide RoHS Declaration of Conformity and ICP chemical analysis reports for C260 orders used in regulated applications.

Brass is one of the most dimensionally stable and predictable metals to machine. Standard CNC turning and milling tolerance for C360 and C260 is ±0.01 mm. Tighter tolerances of ±0.005 mm are routinely achievable on precision turned features, and ±0.002 mm is achievable on specific critical dimensions with appropriate tooling and process control. The excellent machinability of C360 allows consistent dimensional results across high-volume production runs.

Common surface treatments for brass CNC machined parts include: electroless nickel plating (corrosion resistance, uniform coverage on complex geometry), tin plating (solderability, RoHS safe for connectors), gold plating (low-contact-resistance RF connectors and precision contacts), silver plating, zinc-nickel, and clear lacquer or polishing for decorative brass parts. We coordinate all of these treatments as part of the order.

C360 Free-Cutting Brass is used for: threaded fittings and connectors, plumbing valves and valve bodies, pneumatic and hydraulic fittings, electrical connector housings, precision instrument hardware, standoffs and spacers, screw machine products, camera and optical equipment hardware, and any high-volume precision turned component where cycle time and surface finish quality are important. Its machinability rating of 100% makes it the fastest and most economical metal to machine.

Brass can be joined by brazing, soldering, and welding, but conventional MIG/TIG welding is challenging due to zinc volatilization. Brazing with silver-based filler alloys is the preferred joining method for brass assemblies. C260 is more weldable than C360 — C360's lead content further complicates welding. For most brass assembly applications, mechanical joining (threading, press fit) or brazing is specified instead of welding.

C360 Free-Cutting Brass has a machinability rating of 100% — it is the reference material against which all other metals are benchmarked. For comparison: C260 brass rates approximately 30%, 303 stainless rates approximately 45%, 1018 carbon steel rates approximately 78%, and 6061 aluminum rates approximately 90%. This means C360 can be machined at significantly higher cutting speeds with longer tool life and better surface finish than virtually any other engineering metal, making it the most economical choice for high-volume precision turning where material properties permit.