CuZn15 is a wrought copper-zinc alloy at the copper-rich end of the brass family, built around roughly 84-86% copper with zinc making up the balance — a composition close enough to pure copper that it's commonly called red brass or gilding brass rather than yellow brass. That high copper content, combined with essentially no lead (0.05% max) or iron (0.05% max), gives it exceptional cold formability: CuZn15 is the classic choice for deep-drawn eyelet-press work, capable of up to a dozen sequential cupping and drawing operations without an intermediate anneal.

Its low zinc content also gives it excellent resistance to stress-corrosion cracking and dezincification, better than higher-zinc brasses like C27200 or C36000, which is why it shows up in fire extinguisher tanks, ammunition components, pen and pencil barrels, lipstick and cosmetic containers, badges, and architectural trim. What it does not have is any free-cutting additive — no lead, minimal iron — so unlike free-machining brasses, CuZn15 relies entirely on its base copper-zinc chemistry for machinability, and that chemistry sits closer to pure copper's soft, gummy behavior than to a typical machining brass.

CuZn15 is easy to form but only moderately easy to machine — the two properties come from opposite ends of the same low-zinc chemistry. With copper making up 85% of the alloy and no lead to promote chip fracture, the material behaves closer to soft, gummy copper than to a typical free-cutting brass. Chips run long and continuous rather than breaking into short segments, and built-up edge is a real risk at low speeds or with a dull tool, since the soft copper-rich matrix tends to smear and adhere to the cutting edge rather than shear cleanly away from it.

A sharp, high-positive-rake edge is essential here — more aggressive than what a leaded or higher-zinc brass needs — to shear the material cleanly and keep it from dragging and welding to the tool. Moderate cutting speeds work better than pushing to the high end of the brass range: too slow and BUE forms, too fast and heat builds in a material with limited abrasive wear resistance but real gumminess. Coolant helps keep the chip moving and the surface clean, and a ground, polished insert with a keen edge outperforms an as-sintered edge by a wide margin on this alloy.