How faucets are made

A faucet's water channels start as sand: a core sits inside the mold, then gets whirled out with metal balls.

stations: 11
things upstream: 44
raw sources: 23
steps from the ground: 6

The short version

Water channels begin as a core of fine sand set inside a shell mold, and molten brass flows around it. At Oras in Finland, about 3,000 faucets a day go on from there: core whirled out, castings sawn apart, machined, ground, polished, then chrome-plated over roughly two hours. Cartridges go in at assembly, and 1 percent get spot checks.

Bake the sand cores

Fine sand and a hardening agent are heated in a core box until solid. The core is what will leave the water channels open inside the casting.
Prepare the shell mold

A shell mold is dipped in a solution of water and graphite. Next, the caster sets the cores inside and blows out loose sand with compressed air.
Pour the brass

The furnace melts bars of dezincification-resistant brass, a grade Oras picks because acidic Nordic tap water corrodes normal brass. The sealed mold goes into the casting chamber, and molten metal flows into the molds and around the cores.

Goes in
Brass
Whirl out the core

After brief cooling, tongs move the casting aside. A mill full of metal balls then tumbles it until the sand core breaks out from inside.
Saw the casts apart

Saws separate the joined bodies and take off parts needed only for casting. Sawing waste goes straight back into the furnace, and machining chips return to the brass supplier.
Machine the body

A conveyor carries the bodies through automated machining. Small batches of special products may be finished by hand.
Grind and polish

Grinding takes out the rough cast surface and polishing leaves it flawless. After this, bare hands stay off, because fingerprints would show through the plating.
Chrome-plate the parts

Parts go through soaking and washing stages 40 times in about two hours, and chrome highlights any surface flaw. Visible plastic parts first get copper and then nickel layers, which protect against thermal expansion.

Goes in
Nickel Chromium Copper
Inspect and laser-mark

Plated products are inspected before assembly. Brand logos and other markings go on now, mostly by laser.
Install the cartridge

The cartridge that regulates flow and temperature goes in, by hand or machine. Its ceramic discs slide over each other with very little friction.

Goes in
Ceramic
Spot-check and pack

Final inspection stays manual, and 1 percent of completed faucets get spot checks. Sound levels are tested separately, in a silent room with a floating concrete floor.

End of the lineFaucet

Worth repeating

Guest and Chrimes, brass founders in Rotherham, patented a screw-down tap in 1845, the first of its kind.
Ceramic valve discs take advantage of the very low friction between two ceramic surfaces in contact.
Oras says most of the metal in its delivered bars is recycled, because its sawing waste and machining chips get melted back in.