ADDITIVE MANUFACTURING
FEATURE
Trumpf’s TruPrint 5000 system can be equipped with a green laser to enable the processing of larger copper components
processing of larger copper components. Roland Spiegelhalder, Product Manager at Trumpf responsible for the TruPrint 5000 Green Edition, says copper and other highly reflective materials can be printed using green wavelengths “not only efficiently, but also productively and with high quality regardless of geometry”. “Spatter formation is reduced to a minimum and, at the same time, the customer benefits from maximum reproducibility,” he says. Trumpf laid the first foundations for
its green lasers in the field of pulsed lasers, before beginning development of continuous-wave lasers at green wavelengths around 2013. At that time, Spiegelhalder says, the company was quick to recognise the trend toward electromobility – particularly since many components in electric cars are made of copper, including the battery and power electronics systems. “Welding this non-ferrous metal is a major challenge for infrared lasers for obvious reasons. Copper has a reddish tint, meaning it strongly reflects infrared light and the laser’s power does not reach the workpiece,” he says. “Our solution to this problem was to change the wavelength of the laser from infrared to green, using a special crystal in the laser’s resonator. Copper can be welded much better with green wavelength lasers, which provide 20 times higher absorptivity in pure copper compared to IR lasers, making the process much more robust. This creates an efficient and stable process that is easy to develop and less geometry-dependent.”
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“The green laser has positioned itself as a great tool to work with pure copper”
Spiegelhalder says typical applications for Trumpf’s green laser 3D printers (the TruPrint 1000 also comes in a ‘Green Edition’) currently involve producing components with high electrical and thermal conductivity. “The green laser process in combination
with pure copper fits well for heat exchangers or other thermal management applications and inductors, as well as for prototyping in the e-mobility environment and rocket engine components,” he says. Spiegelhalder also highlights a number of
other key advantages of using green lasers for AM – especially when compared with existing approaches. These include “high machine availability” due to industrial thermal system stability, “high process robustness and large process windows”, and “superior surface quality and detail”. Other advantages include elimination of the necessity for the heat treatment of parts, the ability to operate 3D printers using standard pure copper powder, and the fact that green lasers require less support structures than IR-based systems.
Blue laser 3D printers emerging Elsewhere, US-headquartered laser firm Nuburu is working with industrial 3D printing company Essentium on the development of a blue laser-based metal AM
platform. Nuburu provides Essentium with a high-power, fibre-coupled laser system for use in its high-speed extrusion 3D printing platform. As Mark Zediker, the former CEO at Nuburu (he was succeeded by Brian Knaley at the start of November), explains, Essentium developed a processing head that rapidly deposits metal in any direction for part- manufacturing – with the blue laser serving the dual purpose of “providing the heat to melt the wire and the heat to fuse the molten metal onto the surface”. “While the use of a laser beam with a
wire feeder has proven successful with larger core wires over the years, this marks the first development of a commercial product employing a blue laser with a small diameter wire,” says Zediker. In addition to the ongoing Essentium collaboration, Zediker confirms that Nuburu is also now working with “multiple” AM groups to try to fully evaluate the performance of the blue laser in powder bed fusion, as well in directed energy deposition (DED) approaches such as wire feed and blown powder. As part of a recently completed project
with the United States Air Force, GE Additive and Nuburu also successfully built the first blue laser-powered area printer. According to Zediker, this novel printing technology “will provide a dramatic increase in speed, resolution, and scale for powder bed fusion systems”. “We also formally provided the first blue laser AM system to the University of San Diego, where they have conducted extensive studies on the advantages of using blue laser for the DED blown powder
February 2024 Electro Optics 17
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