FEATURE ADDITIVE MANUFACTURING
method of printing. Several papers have been written which describe in detail the advantages of the blue system over an equivalent power IR system,” he adds. In Zediker’s view, the main benefit of using a blue laser for AM processes is the fact that it is absorbed more rapidly across a wide range of materials than an IR laser, which also results in “several key advantages besides speed”. “For example, one major issue is
the clogging of narrow channels often encountered in an IR laser printed part,” he says. “The blue laser has significantly less energy splashing out of laser beams in the powder bed, resulting in less parasitic fusing of powder particles in narrow channels. Consequently, the powder can be easily blown out of channels that are as small as 1mm across. “The blue laser can also process a
wider range of materials than an IR laser, enabling a material-agnostic AM system.”
“Green lasers in combination with pure copper fits well for heat exchangers or other thermal management applications and inductors”
Zediker also notes that the high absorption of blue laser light means a large beam can be used to perform fill-in with little or no fumes being generated. This capability means that blue laser overcomes what he describes as “a major issue with the multi-IR-laser systems today, which process with tight beams that cause significant vaporisation”, and run the risk of vaporised material redepositing on an adjacent area of the build “leading to defect in the part”. “The biggest advantage Nuburu has tested to date is the AM of copper, where
a 200W single mode IR fibre laser was unable to melt the copper powder while a 150W blue laser melted it with ease and enabled 98% part density. We have seen this type of increased speed with improved densification in other materials such as stainless steel,” he says. “The higher absorption of the blue laser beam also means that it takes less energy to melt the powder when printing the part. This means less electricity is needed to print a part and, when compared to an IR laser with the power being provided by less environmentally friendly sources, the blue laser produces 56% less CO2 when printing a part than an IR laser,” he adds.
Blue lasers and blown powder Zediker reports that Nuburu will “continue to explore all aspects of AM and continue to develop and improve its laser sources to provide clear advantages” in the coming years. Against this background, he predicts that blue laser will emerge as “a solid contender in the DED space, whether it be blown powder or wire feed AM”. “We will continue to develop the area printing technology, which we started working on in our Direct to Phase II SBIR programme with AFWERX. We also expect there to be application of our current laser system in powder bed fusion systems, as well as the next generation of blue laser technology,” he says. “The blue laser will enable large single-part fabrication from a single source, higher printing speeds and less powder vaporisation – resulting in more efficient printing, as well as in [fewer] predictable defects in the part.”
A Nuburu blue laser installed in an EOS M-100 printer 18 Electro Optics February 2024
Why green lasers are also ‘Green’ The quantity and range of applications for green and blue lasers in AM processes is likely to increase significantly in the coming years. Spiegelhalder predicts that the process of global decarbonisation will continue, and create “an increased need for electrical applications in all sizes and industries”. “Due to its physics, the green laser has positioned itself as a great tool to work with pure copper. As a result, this technology will be further optimised – and, with the help of the industry and our end customers, find its way into more and more applications. This will continue to reduce costs and enable a larger market,” he says. O’Neill adds: “Future trends will include optimisation of process parameters such as spot size, laser power, and scan rate. As these parameters are fine-tuned, I anticipate that the benefits of visible industrial laser AM systems will become increasingly significant. This will enable a much wider adoption of AM in manufacturing applications.” EO
www.electrooptics.com
Nuburu
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