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<\/p>\nSelective laser melting (SLM) is the premier metal 3D printing technology revolutionizing the additive manufacture of metal parts, but how does it work, and which 3D printers do it best?<\/p>\n
Most metal 3D printers use selective laser melting technology, which involves a laser that melts powdered metal. In fact, this method accounts for more than 80% of the metal 3D printer market and dozens of manufacturers worldwide offer machines in a wide range of sizes with varying features.<\/p>\n
The dominance of SLM tech may not be apparent at first since there\u2019s different terminology in the industry to refer to the same technology. Aside from SLM, there\u2019s direct metal laser sintering (DMLS), direct metal laser melting (DMLM), laser metal fusion (LMF), laser cusing, and laser powder bed fusion (LPBF), among others. This variety of terms begs the question: What\u2019s the difference between them?<\/p>\n
You may be surprised to learn that there is no difference.<\/p>\n
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To get the definitive word on this technology, All3DP turned to one of the inventors of the process,\u00a0Wilhelm Meiners<\/a>.<\/p>\n Just over 20 years ago, Meiners and his colleagues Kurt Wissenbach and Andres Gasser developed and patented the technology while working at the Fraunhofer Institute in Germany.<\/p>\n<\/div>\n<\/div>\n According to Meiners, the technology\u2019s official name is laser powder bed fusion or LPBF.<\/p>\n \u201cThe different names for the LPBF process are due to historical causes,\u201d he says. \u201cIn the early years, every machine supplier created its own name for the same process and kept it until today.\u201d All of these other terms are simply brand names for the standardized technology called laser powder bed fusion.<\/p>\n Indeed, German 3D printer manufacturer EOS coined the term \u201cdirect metal laser sintering\u201d and still uses it today. It\u2019s a bit of a misnomer since the metal powder is melted not sintered, but that could have been lost in translation. SLM, the more popular term, is actually a trademark held by the printer manufacturer\u00a0SLM Solutions<\/a>.\u00a0Concept Laser, on the other hand, called their process laser cusing, but once GE Additive acquired the company in 2016, they changed the name to direct metal laser melting (DMLM). Printer manufacturer\u00a0Trumpf<\/a>\u00a0likes to use the term laser metal fusion while 3D Systems uses direct metal printing.<\/p>\n Although we used the most popular term, selective laser melting, in the title of this article, for the rest, we\u2019re going to go with the official name used by Meiners and the standards organization ASTM:\u00a0laser powder bed fusion.<\/strong><\/p>\n Despite the confusing terminology, LPBF is one of the most exciting 3D printing technologies available today. It\u2019s used across industries for rapid prototyping, specialty high-performance parts, and mass production with a wide range of metals. Let\u2019s take a look!<\/p>\n LPBF 3D printers use high-powered lasers to selectively melt a metal powder. The melted parts fuse together layer-by-layer on a molecular basis until the homogenous model is complete.<\/p>\n Printer operators can use \u201cpure\u201d metal materials, although alloys also see regular use. There are dozens of metals available for the LPBF process, but some of the most common materials include:<\/p>\n In theory, LPBF \u2014 like the related and similarly functioning\u00a0selective laser sintering (SLS)<\/a>\u00a0for plastics \u2014 is a support-less AM technology. The packed powder on the printing bed provides support to the model during the printing process.<\/p>\n However, due to high thermal gradients between the molten part and surrounding powder, stresses can arise causing warpage and distortion. Support structures are therefore often needed in order to dissipate heat from critical areas and fix the part securely onto the build plate. A general rule of thumb is that overhangs or hollow structures angled between\u00a00 and 45 degrees<\/a>\u00a0should be supported.<\/p>\n An LPBF 3D printer houses metal feedstock powder. The printer\u00a0pushes powder<\/a>\u00a0into the chamber where a coater blade (like a windshield wiper) or roller spreads it into a thin layer across the substrate or build plate.<\/p>\n Next, a high-powered laser fuses a two-dimensional slice of the part by selectively melting the powdered material. The build plate then lowers by the height of one small layer, and the coater spreads another layer of fresh powder across the surface. The printer repeats these steps until you have the finished part.<\/p>\n Some printers have bidirectional coaters, which can push powder onto the bed moving both ways, speeding up the coating process\u00a0by up to 40%. Another way LPBF printer manufacturers make printing faster is by employing more powerful or several lasers.<\/p>\n A small, compact LPBF printer might have a single 30-watt laser. As the machines grow larger, they can start incorporating stronger lasers or multiple lasers in one array. For example, the AddUp\u00a0FormUp 350<\/a>\u00a0features four 500-watt lasers, while the SLM Solutions NXG XII 600 employs a total of 12 lasers, each with 1000 watts of power.<\/p>\n Increasing the power or number of lasers means the printer can melt the metal powder more effectively. It directly results in faster build rates and increased throughput, and typically a higher price tag. As an example, SLM Solutions claims the\u00a0NXG XII 600<\/a>\u00a0can provide 20 times faster build rates than single-laser systems, up to 1,000 cm3\/h.<\/p>\n Depending on your application, when considering in a LPBF 3D printer you\u2019ll look at the level of laser power, the laser beam diameter, the scan speed, the possible layer thickness (from 20 to 120 \u03bcm), the scan strategy, the part cooling strategy, and other features that set different brands, and different models within brands, apart.<\/p>\n The LPBF printing process happens in a controlled atmosphere inside the machine, which means inert gas (nitrogen or argon) fills the build chamber.<\/p>\n Once the part is built, it can be removed from the machine after cooling. Large parts can take many hours to cool before handling is possible. Metal powder that is not fused is collected afterwards and reused for further LPBF projects. Printed parts are initially attached to the build plate, from which they are usually separated by cutting or machining, or by wire erosion.<\/p>\n If the part needed supports, you must next remove them as well. As LPBF printers don\u2019t use separate support materials, this can be a difficult and time-consuming process.<\/p>\n The\u00a0surface finish<\/a>\u00a0of the final melted part is rough and, depending on your requirements, it may need post-processing to achieve a smooth and shiny result. It is also relatively common to further machine parts to achieve tighter tolerances and finish fine features, surfaces, and holes.<\/p>\n LPBF, like every manufacturing technology, has its strong and weak points. The pros and cons of producing a model via LPBF include:<\/p>\n One of the most common questions when it comes to metal 3D printing is how part strength and durability of 3D printed parts using LPBF compare to traditional metal manufacturing methods.<\/p>\n Nick Estock, product manager at\u00a0AddUp<\/a>, the French metal 3D printer maker, explains to All3DP that it is possible for LPBF to produce parts with mechanical properties similar to traditional manufacturing. However, he adds, there are some caveats.<\/p>\n \u201cTraditional manufacturing is subtractive and starts with a base material of known mechanical properties through very controlled and mature processes. In any additive manufacturing process, including LPBF, the material is being created simultaneously with the part. The process is fundamentally different and therefore not equivalent,\u201d says Estock.<\/p>\n Donald Godfrey, global director of business development for aviation and defense at\u00a0SLM Solutions<\/a>, agrees. He further explains that the SLM process creates parts that have smaller microstructures than cast metal components. This gives them higher tensile properties, but cast parts are currently still stronger.<\/p>\n \u201cTypically, LPBF technology is used to replace cast components. In unique cases, printed components can replace forgings,\u201d he adds.<\/p>\n When we asked Meiners if the resulting prints from the LPBF process are equivalent to traditional manufacturing processes, he also said, it depends.<\/p>\n \u201cThe properties of LPBF parts can obtain or even exceed those of traditional manufactured parts, but this depends on several conditions like the metal material (steel, aluminum, titanium, etc.) the post process (heat treatment, hot isostatic pressing, etc.), the traditional manufacturing process you compare it with (casting, forging, etc.), and the specific part property (strength at static load, high cycle fatigue, creep, etc.).\u201d<\/p>\n In the end, there\u2019s no general answer, Meiners says. \u201cIn many cases, LPBF parts obtain the same properties, but not as a generic standard.\u201d<\/p>\n Let\u2019s take a look at some real-world examples of LPBF 3D printed parts in action.<\/p>\n LPBF is used in nearly every industry today where traditional metal manufacturing is employed including aerospace, automotive, medical, energy, and machining.<\/p>\n What connects all these industries is their need to produce more efficient and better-performing metal parts, faster, and at a lower cost. Although LPBF is also widely used for faster and cheaper production of spare and replacement parts, where the technology shines is in producing complex shapes and innovative product design enhancements that are not possible with any other metal manufacturing methods. With LPBF, multi-piece components can be 3D printed on one part, products can have internal lattice structures to make them weigh less, and complex internal channels that would be impossible to machine.<\/p>\n Metal 3D printing, in general, also eliminates the need to maintaining standing inventories and ship parts from long distances, plus it\u2019s more sustainable in that it uses and wastes less raw material.<\/p>\n Let\u2019s take a look as some specific, real-world applications of LPBF in action.<\/p>\n<\/div>\n Safran Landing Systems and SLM Solutions worked together to improve a previously forged nose landing gear part for private jets.<\/p>\n At 455 x 295 x 805 mm, the\u00a0landing gear component<\/a>\u00a0is the world\u2019s first LPBF printed part of its size, says SLM Solutions. Since the component is a part of the system that transfers loads from the wheel to plane\u2019s structure, it was manufactured out of titanium. The choice of material gives the part strong mechanical properties while being corrosion-resistant without coatings.<\/p>\n It was printed using the quad-laser SLM 800 machine. Not only is the LPBF printed component 15% lighter than a traditionally forged component, the technology also slashed the turnaround time.<\/p>\n \u201cAdditive manufacturing contributes to save time in the qualification and certification phases by rapidly providing the parts for testing. We were able to produce the main fitting in a few days vs. a few months with the forging process,\u201d says Gerhard Bierleutgeb, EVIP of Global Services and Solutions at SLM Solutions.<\/p>\n LPBF can replace traditional manufacturing methods in many instances, but they can also work together. Traditional production methods are no longer used\u00a0to create tool segments<\/a>\u00a0for hot forming car parts, which is why Audi has replaced them entirely with 3D printed alternatives.<\/p>\n \u201cWhenever conventional manufacturing methods reach their limit, we use additive manufacturing \u2014 which lets us meet quality standards and comply with production times,\u201d said Audi Metal 3D Printing Center\u2019s Project Manager, Matthias Herker.<\/p>\n Audi uses the\u00a0EOS M 400<\/a>\u00a0printer to manufacture hot forming segments and high-pressure die casting tool inserts. The individual segments can be up to 400 mm in length and weigh up to 120 kg.<\/p>\n LPBF 3D printing allows Audi to create topology-optimized, highly complex cooling channels, fine-tuned to the needs of specific components. As a result, the premium car manufacturer has been able to shorten cycle times and get more even cooling, which improves part quality.<\/p>\n Lumbar\u00a0interbody fusion devices\u00a0\u2014 or spinal cages \u2014 are widely used to treat patients suffering from back issues, such as degenerative disc disease.<\/p>\n GE Additive produces an additively manufactured option made from titanium powder using LPBF printing. These new spinal cages offer several benefits over machined versions, the company says.<\/p>\n Due to additive manufacturing\u2019s greater design freedom, the spinal cages can be made lighter with larger windows and lattice structures. This not only reduces manufacturing costs, but makes the cages more effective as doctors can implant additional bone graft into the cage. It\u2019s also possible to create customized porous structures that mimic human bone, which can further promote bone formation.<\/p>\n The new cages don\u2019t require any coatings, which completely eliminates the risk of delamination. They\u2019re also made of titanium, which is biocompatible and reduces cage migration and bone degradation.<\/p>\n Orano, a French multinational nuclear fuel cycle company, struggled with long lead times and high costs of obsolete spare parts. In early 2021, the company partnered with AddUp to evaluate LPBF\u2019s technical and economic feasibility for their operation.<\/p>\n Using the FormUp 350 printer, Orano and AddUp created several copies of a 3D printed material transfer bridge and a\u00a0steam distribution block<\/a>, which has particularly long lead times when manufactured through traditional methods. The parts had identical design and mechanical characteristics to the originals.<\/p>\n Thanks to the use of fine stainless steel powder, the 3D printed parts had a high geometric accuracy and surface finish, particularly in their internal channels. Additionally, at the cost of three machined parts, Orano was able to print 16 additively manufactured components.<\/p>\n \u201cThe result is unexpected: the same design with complex geometries, the same mechanical characteristics, and above all, a 50% reduction in production costs compared to machining. Thanks to metal additive manufacturing, Orano now has an additional, agile, reliable, and economical supply chain for spare parts,\u201d says Ana-Paula Serond, innovation manager at Orano.<\/p>\n If you\u2019re not ready to purchase your own LPBF machine, there are services to make your parts for you. Generally, there are two different kinds: 3D printing on-demand manufacturers and printer manufacturers.<\/p>\n Metal printer manufacturers, including 3D Systems, GE Additive, and EOS, offer metal part-on-demand services. These are ideal because working directly with a printer manufacturer also gives you a chance to demo their machines\u2019 capabilities in case you want to buy one. If you\u2019re considering a metal 3D printer purchase for your operation, it might be worth it to order some on-demand parts from a manufacturer to evaluate the machine \u2013 especially if you already have a specific printer in mind.<\/p>\n The printer\u2019s manufacturer will know the ins and outs and limits of their technology down to the smallest details. This can make it easier for them to assist you with the choice of technology, materials, and parts design.<\/p>\n It could also be that you already own a printer from one of these companies, but your machine is just too busy to deal with a suddenly increased workflow. Ordering on-demand printing services from your trusted manufacturer is a good option for getting more parts done, and you\u2019ll know exactly what kind of part quality you\u2019ll get.<\/p>\n For all these reasons, consider these best on-demand metal printing services offered by 3D printer manufacturers.<\/p>\n 3D Systems<\/a>, based in South Carolina, has an on-demand manufacturing service that\u2019s so popular they just sold it to a private equity firm. The new company will operate as QuickParts and can produce parts in steel, aluminum, titanium, cobalt chrome, and nickel alloy. They offer printing and consultation service globally, and can also provide additional services like CNC machining and casting patterns.<\/p>\n GE Additive Print Services,<\/a>\u00a0part of the General Electric group, makes use of their EBM and DMLM metal 3D printing technologies, most of which have been obtained through mergers and acquisitions. They also provide their own materials, as well as their consultancy and training services. They focus on medical, automotive, military, dental, and aerospace industries. Although their services aren\u2019t available online, they do offer US customers a full range of printing services via their Print Services Center in Pittsburg. The company also provides limited services in Europe through their Lean Manufacturing facilities.<\/p>\n Although Germany\u2019s\u00a0EOS<\/a>\u00a0doesn\u2019t directly 3D print your metal parts, they do have a handy list of additive manufacturers with EOS machines who do contract manufacturing all over the world, including several in Africa, an underserved area.<\/p>\n AddUp, metal 3D printer OEM and parts producer, works with customers in the medical, automotive, energy, aerospace, tooling and defense industries to print production parts. They offer part design and optimization for AM, consulting services and training, proof-of-concept production, serial part production and post-processing, plus ISO 9001 and ISO 14001 certified. With production workshops in Europe, US, and Asia, AddUp just opened a new 20,000-square-foot facility in Cincinnati, Ohio. The US-based facility is ITAR compliant.<\/p>\n Laser powder bed fusion 3D printers come in a range of sizes and powers. Here we feature the \u201cstarter\u201d solutions from the top manufacturers, but many companies also offer larger and more feature-rich machines tailored to address specific manufacturing challenges and industry segments.<\/p>\n<\/div>\n![\"\"](\"https:\/\/img.facfox.com\/imgs\/2022\/03\/da9999c42df956c4.png\")
\n\nHow Does LPBF Work?<\/h3>\n<\/div>\n<\/div>\n
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LPBF vs. Traditional Manufacturing<\/h3>\n
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<\/p>\nADVANTAGES<\/h4>\n
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DRAWBACKS<\/h4>\n
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![\"\"](\"https:\/\/img.facfox.com\/imgs\/2022\/03\/a844a4ea7af5ca93.png\")
LPBF vs. Traditional Manufacturing<\/h3>\n
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WHO\u2019S USING LPBF TODAY?<\/h3>\n
![\"\"](\"https:\/\/img.facfox.com\/imgs\/2022\/03\/1e0261f19889ee49.png\")
\nAerospace: Landing Gear<\/h3>\n
![\"\"](\"https:\/\/img.facfox.com\/imgs\/2022\/03\/4e0a25958b2a2aac.png\")
\n\nAutomotive: Tools<\/h3>\n<\/div>\n<\/div>\n
\n![](\"https:\/\/img.facfox.com\/imgs\/2022\/03\/13cfc6234747aaf6.png\")
<\/div>\n<\/div>\n![\"\"](\"https:\/\/img.facfox.com\/imgs\/2022\/03\/3117da2c75e5b3ef.png\")
\n\nMedical: Titanium Implants<\/h3>\n<\/div>\n<\/div>\n
\n\n![\"\"](\"https:\/\/img.facfox.com\/imgs\/2022\/03\/d2637b854838566d.png\")
Energy: Steam Distribution Block<\/h3>\n
![\"\"](\"https:\/\/img.facfox.com\/imgs\/2022\/03\/040e8edb1b695a56.png\")
GET YOUR METAL PARTS MADE: CONTRACT MANUFACTURERS<\/h3>\n
![\"\"](\"https:\/\/img.facfox.com\/imgs\/2022\/03\/8733698c1ff4a1ee.png\")
Top Manufacturer Metal 3D Printing Services<\/h3>\n
3D SYSTEMS \/ QUICKPARTS<\/h4>\n
![\"\"](\"https:\/\/img.facfox.com\/imgs\/2022\/03\/a4ac8787ef34f141.png\")
GE ADDITIVE<\/h4>\n
EOS<\/h4>\n
![](\"https:\/\/img.facfox.com\/imgs\/2022\/03\/32dfc08d6c1c2ff0.png\")
<\/p>\nADDUP<\/strong><\/h4>\n
\nTOP LPBF 3D PRINTERS<\/h3>\n<\/div>\n
\nWhen selecting a LPBF 3D printer, consider:<\/h3>\n
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One Click Metal MPrint+<\/a><\/h3>\n
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