A new laser sintering process developed in the US uses just 1.5kg of titanium alloy powder to produce a 1kg finished aircraft part, compared with the 10-20kg of powder usually needed to produce a 1kg forging.
No moulds or dies are needed, enabling companies to design and deliver titanium components in as little as four weeks instead of the 12-18 months typically needed for a new forging. Boeing has already ordered $1m worth of titanium wing parts produced by this method for full-scale testing for its new US Navy aircraft programme.
The AeroMet Lasform process uses a laser to trace out a component’s shape onto a titanium base plate, taking design data directly from the part’s CAD file. Titanium alloy powder is then fed into the molten metal bead produced by the laser to build up the component layer by layer. The laser `pre-form’ then requires only light machining to produce a finished component.
According to Minnesota-based AeroMet, set up in 1997 to develop the process as part of a US government-funded research and development programme, the mechanical properties of laser-formed components are as good as or better than those of conventional forgings.
The process uses commercially available titanium alloy powders, making it possible to vary the composition of the alloy across a component by mixing in different alloying elements during the process. Since the process is conducted in an inert atmosphere of argon, it can also be used to laser-form niobium, rhenium and other exotic metals. So far AeroMet has produced prototype components up to 2.4m long and weighing 270kg.
The laser forming of near net shape components by this method gives increased material usage, faster lead times, lower tooling and machining costs and equal or better mechanical properties, says AeroMet. And it allows designers to combine several components.
The company is now installing a second machine to bring its laser-forming capacity up to 18,000kg a year.
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