FEATURE: ADDITIVE MANUFACTURING
LASERS INITIATE COPPER 3D PRINTING TAKE-OFF
A 3D-printed
copper rocket nozzle
Trumpf enables copper additive manufacturing by combining its TruDisk 1020 with its TruPrint systems
Optically-driven additive manufacturing is entering uncharted territory with challenging reflective, thermally conductive metals such as copper, finds Andy Extance
When a space industry customer approached Stratasys Direct Manufacturing to make bespoke additively manufactured components, it fittingly pushed the ‘service bureau’ to explore new frontiers. They wanted intricate injectors and nozzles for rocket engines made from copper alloys, explained Andrew Carter, a senior process and manufacturing engineer at the firm. The components needed passageways through them to allow coolant to flow and
12 LASER SYSTEMS EUROPE SPRING 2020
stop them melting at fuel combustion temperatures. The kind of 3D printing processes Stratasys Direct offers would be ideally suited – yet the company didn’t work with copper alloys at that point. Carter and his colleagues at the
Californian firm decided to develop a dedicated direct metal laser sintering additive manufacturing process based on the industry-recognised C18150 copper/ chromium/zirconium alloy. This approach
typically uses infrared lasers to melt small pools of metal powder, fusing it together. Patterns form, as if drawn by an invisible hand, as the laser’s energy fuses the particles, then disappear as they’re completed and masked by a fresh powder deposit. The process repeats, the layers pile up, and the three-dimensional objects gradually form. ‘The challenge with copper is that it’s
very thermally conductive,’ said Carter. ‘And making things more challenging, it’s very reflective of the laser wavelength in its molten form. So the energy flux going into the powder bed is very critical. And it’s very challenging to hold a stable melt pool at industry-standard deposition rates.’ To develop the approach, Stratasys Direct
used infrared laser systems made by EOS that allowed Carter and his colleagues to adjust laser power, scan speed and layer thickness. A key final criteria was whether
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Stratasys Direct Manufacturing
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