How brass is made

Brass is copper with zinc stirred in, and it is soft enough to cast, extrude or machine into almost anything.

stations: 6
things upstream: 24
raw sources: 12
steps from the ground: 4

The short version

Brass is an alloy of copper and zinc, generally about two parts copper to one part zinc. Foundries melt copper, add zinc and sometimes small amounts of lead, tin or aluminum, then cast billets. The billets are extruded or rolled into rod, tube and sheet, and often machined into fittings. Nearly 90 percent of brass is recycled.

Melt the copper

Refined copper is melted in a furnace. Brass melts at a low temperature for a metal alloy, between 900 and 940 °C depending on composition, so it flows easily into molds.

900 to 940 °C

Goes in
Copper
Stir in the zinc

Zinc goes into the bath in a proportion set by the grade. More zinc makes brass harder and paler, and more copper makes it redder and softer. Brass with 15 percent or less zinc stands up well to zinc loss.

Goes in
Zinc
Tune with minor metals

Small additions change what the brass does. About 2 percent lead makes it cut cleanly on a lathe. Tin helps it survive seawater, and aluminum makes it stronger and more corrosion resistant.

Goes in
Lead Tin Aluminum
Cast billets

The melt is cast into logs called billets, ready to be heated and pushed or rolled into shape. Brass is easy to cast because of its low melting point and flow characteristics.
Extrude into rod and tube

A press pushes hot billet through a shaped die and out comes a continuous length of rod, tube or profile. Brass is more malleable than bronze or zinc, so it forms readily.
Machine the fittings

Brass bar is turned and milled on machines into locks, valves, hinges, plumbing fittings and zippers. Its softness and low friction are the reasons it is used.

End of the lineBrass Next it goes into aa battery, mechanical wristwatch, faucet and 23 more.

Worth repeating

Salt water slowly leaches the zinc from ordinary brass and leaves porous copper behind, so ships use marine brass with about 1 percent tin.
Brass is often used in tools and fittings that must be non-sparking, near flammable or explosive materials.
Brass is the usual metal for instruments built from long, narrow tubing, because it is malleable and easy to work.