Spray Forming

Spray forming is a metal-casting technique that builds up a near-net-shape metal billet from a spray of semi-solid droplets rather than pouring liquid metal into a mold, producing a fine, uniform internal grain structure with far less of the segregation and coarse crystals that ordinary casting leaves behind. In the process, an alloy is melted in an induction furnace and allowed to fall as a thin stream through a ceramic nozzle, where a ring of high-pressure gas jets breaks the stream into fine droplets; these droplets are still partly molten when they strike a collector, and they build up layer by layer into a solid billet as the collector moves beneath the spray. The technique was pioneered in the 1970s by Professor Singer at Swansea University in Wales, whose gas-atomized version of the process was commercialized by Osprey Metals, later Sandvik Osprey, of Neath, Wales, and it is now used to produce specialized alloys, including lithium-aluminum alloys and metal matrix composites, that are difficult or impossible to manufacture by conventional casting.