First it was two, then four. Then it was eight, quickly followed by 10 and 12. A quick search for ‘multi-laser’ across TCT Magazine shows we’re now at 64, but there’s every chance we’ll have surpassed that by the time this article (first seen inside this print issue of TCT) hits your desk.
The rising number of lasers inside metal additive manufacturing (AM) systems over the last five years has been a source of excitement while serving somewhat as an indicator to the progress being made in powder bed technology. Yet, away from the productivity gains and larger build volumes, these systems are increasingly intricate beasts, with each laser or millimetre adding further complexity to the process parameters and factory floor space considerations of an already complex technology.
Nikon SLM Solutions was one of the first companies to introduce a multi-laser machine when it launched its twin laser SLM 280 over a decade ago. The hardware, now in its third generation with the SLM 280 PS, has been put to work by brands such as Audi and Bugatti, but much like additive itself, the market’s acceptance wasn’t always running at the same pace as the technology.
“The market was hesitant to believe that part quality is not an issue in multi-laser systems, even if you master handling multiple lasers sharing a common space,” Benjamin Haas, Product Marketing Manager at Nikon SLM Solutions, told TCT. “Once this was understood, it enabled applications for AM to grow in size, which in return requires more lasers to still manufacture efficiently.”
Today, Nikon SLM Solutions’ flagship machine is the NXG XII 600, a 12-laser, 600 x 600 x 600 mm selective laser melting system with a combined laser power of 12kW. Adopted by the likes of Divergent Technologies and GKN Aerospace, with several users installing multiple machines, the company believes its success is owed to an understanding that productivity does not simply mean more laser power.
“We have always looked at overall productivity from build job start to finish as well as machine turnaround times,” Haas explained. “With the SLM 500, we introduced the first removable build cylinder which decreased the time between two jobs to less than one hour. When designing the NXG, it was obvious that we would follow the same concept. Imagine a machine of that size sitting idle while you are unpacking!”
More lasers, more problems?
That end-to-end consideration is key. A big machine is great if your aim is to build large or multiple parts, but how do you store your materials? How do you remove parts? How do you maintain and service? These are the kinds of questions going through metal AM expert SJ Jones’ mind when assessing any new multi-laser technology.
“It generally terrifies me,” Jones said “How am I going to qualify that? How am I going to ensure that is accurate, laser-to-laser? If one laser goes down, can another laser cover for it? There’s a lot of things that I have to worry about when I add more lasers versus revamping an existing platform to make it more reliable or give me more capability.”
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A report by the UK's Manufacturing Technology Centre positioned the effect of multiple lasers interacting with one another as one of multi-laser AM's biggest technical challenges. Failure to optimise ‘stitching’ between lasers could lead to a higher level of defects.
“Our experience tells us that users need to consider how the lasers interact with each other – not only in terms of laser overlaps on a single part but also whether the gas flow would carry smoke and spatter from one melt pool and affect another laser,” Alex Hardaker, Advanced Research Engineer, AM at the MTC, told TCT. “These effects and their impact on the parts made should be taken into account when considering the qualification routes, which would increase the amount of testing required. What’s more, users need to understand how calibration drift affects their multi-laser machines over time, and the resulting properties of the parts made, so that appropriate calibration intervals can be set.”
“It's really a physics problem that we're trying to solve,” Jones said, “because you can only pump so much heat and thermal mass into that. You've got melt pools, powder physics. So, finding the optimal layout, not only of the lasers, but the number of the lasers. Do you want to use a rectangular layout? Do you want to use a circular layout? How are you going to clean the windows? Also, lasers have angles that they hit the powder bed at that are most optimal and least optimal. There’s so much physics happening in that tiny chamber!”
Rather than laser count, Jones and Hardaker are paying closer attention to incremental developments happening in areas like beam shaping and scanning strategies. They point to the collaboration between EOS and nLight, which will implement a series of complementary laser-based technologies and give EOS users access to different beam profiles to increase productivity. Similar iterative steps were made last year by Renishaw, one of the first companies to introduce a four-laser printer, which opted to forgo the trend for more lasers and introduced TEMPUS, a patented technology based on a new scanning algorithm that allows lasers inside its RenAM 500 system to fire while the powder recoater is moving.
All the single lasers
TCT
AMCM M 8K printed rocket part at TCT Japan
The demand for multi-laser is largely being driven by the aerospace sector. Collins Aerospace purchased its second SLM Solutions NXG XII 600 system just two years after investing in its first, while Sintavia, a Florida-based metal AM provider to aerospace and defense, outlined plans in April for its largest investment in facilities and equipment since 2019, including its second NXG XII 600 and a third AMCM M4K-4 system. The company was also the North American launch customer for AMCM’s M8K-K, equipped with eight lasers and an 800 x 800 x 1200 mm build chamber. At the time, Sintavia CEO Brian Neff commented: “Whoever says that there are no economies of scale in AM hasn’t been running a large enough printer.” But it takes work to ensure those levels of efficiency, and as Haas explains, more lasers does not automatically equate to lower cost-per-part, higher productivity, or the same part quality.
“First of all, the important question is: how many lasers of what type and laser power do I need for the applications and business cases I want to target?” Haas said. “Second, a lot of technical boundary conditions come on top, such as: how do I use my lasers wisely to avoid any unnecessary laser downtime or unwanted laser interference? How do I ensure my thermal management if laser power, and therefore energy, increases to avoid structural issues and ensure consistent part quality? If more lasers, especially with higher laser power, operate at the same time, it is crucial to maintain a clean atmosphere in the chamber, so consistent gas flow quality throughout long-lasting builds is critical to part quality. In the end, a machine is only as good as its processes, so our material parameters are key enablers to ensure that our systems deliver what they promise.”
On a visit to GE Aerospace's Additive Technology Center (ATC) in Cincinnati last year, Executive Manufacturing Enablement Leader Chris Philp shared with TCT how the engine manufacturer relies on both single and multi-laser systems depending on the application. For certain large parts where confidence has already been built on a single-laser platform, it simply doesn’t make sense to add more lasers. However, with four quad-laser Concept Laser M Line systems installed, the company has been exploring how four lasers can be leveraged for parts developed on single laser machines to reduce build times from one month to two weeks, without affecting part quality. These quad-laser systems are said to be important to future growth and efficiency, according to Philp, “otherwise we’re building multiple factories instead of one.”
Hardaker added: “One of the starting points is to look at how products built on these machines compare with those made on smaller ones, using both single-laser as well as multi-lasers with similar build conditions/locations. It is key to understand the fundamentals of the machines before then scaling up to build bigger and bigger components.”
Additive Industries has recognised this need for ‘less is more’. The Dutch manufacturer teased its own 10-laser machine in 2020 but recently confirmed to TCT it has "decided not to pursue the MetalFAB600 at this time". Instead it is prioritising development of its 420 x 420mm system and new MetalFab 300 Flex, the latter designed to lower the barriers to AM with either two or four 500-watt laser configurations. It said: "We recognise that the majority of the market demand resides within the medium (200- 350mm) and large (350-600mm) system categories, and we are directing our research and development investments accordingly."
On an episode of the Additive Insight podcast, Sandra Poelsma, Print Process Architect at Additive Industries spoke about matching machine developments to the needs of the end-user.
“I personally always ask the question, why?” Poelsma said. “Why would you add more lasers? Why would you add a larger build platform? The larger build platform enables you as a customer to produce larger parts [...] and more lasers [are] needed, of course, to be able to cover all the build area. [...] I think challenges like laser-to-laser calibration, making sure that all the lasers are working simultaneously together is vital and I think that will be a bigger challenge, but I do question, is that really added value for the customer? Does it help to adopt additive manufacturing, even further lowering these barriers?”
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Multi-laser printing on the show floor at TCT Asia 2024
In the laser race, there’s a sense that the AM industry is only competing with itself as opposed to the traditional processes it strives to stand alongside. But there are other areas of hardware development, away from more lasers, which could have a substantial impact for end-users and their efficiency.
“If [an OEM] made the powder hopper bigger so it could hold more powder, I'd be thrilled,” Jones said of the developments they would favour. “If they had a qualification framework, that would be really exciting. If one of the OEMs partnered with NIST or one of the material testing bodies and said ‘we have now published all of this data to help qualify your parts, so if you print on our machines, we can guarantee you qualified material’ that would be nice. But more lasers? It's great to have because we can print faster [reigning in several hours or even days can really improve productivity] but in the grand scheme of all manufacturing, we're competing with castings and forgings, which means that I really only have to beat a lead time of 365 days. For context, most of my large-format prints range from 4 to 21 days.”
64 and counting
Earlier this year, Eplus3D made the highest bid for laser count when it launched its EP-M2050 system at TCT Asia. The 36-laser platform can be extended to accommodate 49 or 64 lasers, while its 2050 x 2050 x 1100 mm build envelope can be extended up to 2000 mm in the Z-axis. Vendors like BLT and Farsoon have also been at the forefront of this multi-laser trend, with laser count ramping up in the last two years to deliver bigger parts and competitive print times. The most recent report from CONTEXT found shipments of industrial metal powder bed fusion systems were up 45% in China, with four of the top five global vendors in this category headquartered there. According to these CONTEXT figures, Eplus3D led the industrial segment in terms of shipments for the period, while Nikon SLM Solutions was also identified as a leader in large form-factor, multi-laser systems. Still, as Eplus3D told TCT, any large concentration of lasers requires additional technical consideration, and the company has equipped its machine with a standard six-by-six laser matrix and 36 galvanometers to ensure all lasers operate in sync. For the 64-laser configuration, it’s fitted with an eight-byeight laser matrix and 64 galvanometers.
“Advancements in technology augment the feasibility of multi-laser integration, incorporating power enhancements, optical optimisations, and algorithmic breakthroughs, fuelled by the escalating demand for metal additive manufacturing in sectors like aerospace, automotive, and medical for fabricating large, intricate components,” Mary Li, General Manager, International Division at Eplus3D, told TCT. “Addressing technical hurdles like laser interference and instability is paramount. Innovative solutions and process refinement are key to achieving this. Similarly, cost containment requires a focus on production scale, technological advancements, and cost reduction.”
Li shared how operational complexity rises with more lasers, and requires close management of variables like sync, energy distribution, and cooling. It is crucial that users weigh their initial investment for extra lasers against potential operational cost hikes and conduct ROI analysis to ascertain cost-justification based on productivity gains. To assist that, Eplus3D is building customised machines where users can choose the number of lasers and build size to match their requirements. The company says these machines are being designed for ease of operation and maintenance, and to mitigate the complex learning curve and maintenance schedules for multi-laser AM.
Looking ahead, Li believes systems exceeding 64 lasers will emerge. The expectation is that this will drive ‘a new era of growth for metal AM’ with more efficient, high-quality, lower cost systems. To prepare for that future, Li suggests users should be evaluating the scalability of machinery for additional lasers to adapt to future materials, geometries, and production needs.
“The precise timeline for equipment boasting more lasers hinges on tech advancements and market demand shifts,” Li added. “At the same time, we must anticipate challenges and issues in tech development, actively pursuing solutions to foster the sustained, healthy expansion of metal additive manufacturing.”
This article originally appeared inside TCT Europe Edition Vol. 32 Issue 4 and TCT North American Edition Vol. 10 Issue 4. Subscribe here to receive your FREE print copy of TCT Magazine, delivered to your door six times a year.
