ADDITIVE manufacturing, as it is known to those who use it - or 3D printing, as the rest of the world more poetically calls it - is unlikely to replace the metal bashing of mass production anytime soon.
But for bespoke applications, even those that must meet tough engineering requirements, or "tolerances", it may oust more traditional methods surprisingly quickly. Building a machine's components a layer at a time means that complicated shapes can be made more easily than by starting with a lump of metal and removing what is not needed. There is also far less waste.
The latest straws in the wind come from the world's antipodes. In Britain Rolls-Royce, a large engineering firm, is testing the technique for making parts of commercial-jet engines. In Australia a group of researchers at Monash University, in Melbourne, has built an entire, albeit small, such engine this way.
Rolls-Royce's plan is to use 3D printing to construct the front bearing housing of its Trent XWB-97 engines. The bearing housing includes 48 aerofoil vanes which guide air into the jet's compressor. It is 1.5 metres in diameter, measures half a metre from front to back, and is made of an alloy of titanium and aluminium.
Engineers in Rolls-Royce's additive-manufacturing division, led by Neil Mantle, have been making experimental bearing housings for the Trent using a version of 3D printing that employs a beam of electrons to melt layers of powdered alloy. The melted alloy then solidifies and adds to the growing structure. On-the-ground tests are encouraging, but proof will come when a plane powered by the tweaked Trents takes off--which the firm hopes to try out later this year.
The Monash device, put on display in the closing days of February at the Australian International Airshow, is what is known as an auxiliary power unit. It generates electricity rather than thrust and is used, among other things, to help start an aircraft's main engines. It works, though, on the same principles as a jet that is designed to propel an aircraft.
Wu Xinhua of Monash's Centre for Additive Manufacturing (pictured, with a disassembled version of the engine) and her colleagues based their power unit on a model built by Safran Microturbo, a French firm with which they are collaborating. They used a laser, rather than an electron beam, to do the melting. The result - whose components are made from titanium, nickel and aluminium alloys - is 60cm long and 40cm in diameter when assembled, and weighs 38kg. Whether it works has yet to be determined, but a test is planned.
Like Rolls-Royce, Safran does not intend to print entire engines routinely. Some parts, such as the central shaft, remain easier to make by standard "subtractive" manufacturing. But both firms' interest shows that a technology which was, not so long ago, regarded by many as a bit of a toy, really is now ready for some heavy-duty work.