In just a few short years, 3D printing of aluminum has gone from something that was seen as a relatively challenging feat without a whole lot of commercial activity outside of a few users who had perfected some ‘black magic’ additive manufacturing (AM) expertise with the metal, to one of the fastest growing metal groups in additive manufacturing in 2018. Demand for aluminum additive solutions isn’t slowing down, and growth is likely going to continue ramping up. If you’ve been following metal AM at all over the last year, none of this probably sounds like news to you. When you take a high enough view of the industry, however, aluminum printing still looks pretty underrepresented. There are several reasons for this. If you’re just comparing shipment numbers that are based on the mass of metal powders sold (as is common in the industry), aluminum as one of the least dense metals commonly printed doesn’t show up with big shipment numbers compared to dense materials like steels or nickel superalloys. If you take the mass of the material out of the equation, SmarTech estimates that aluminum printing accounts for about 10 percent of all metal printing today. Clearly, that percentage is higher in certain industries that have adopted metal AM and lower in others.
Printed aluminum has always been in highly sought after, but it hasn’t been until the last couple of years have a wider group of users mastered the processing requirements to get stable, productive, high quality aluminum parts. Some users have been aided by the machine community who have collectively expanded their process parameter sets to include aluminum as an ‘approved’ or ‘optimized’ material for use in their systems for customers who don’t want to invest the R&D time to stabilize the process themselves.
But there’s also suddenly a lot more options for aluminum printing using powder bed fusion. Even through to today, one alloy has accounted for a huge proportion (essentially 100 percent in the recent past) of aluminum AM. Even though they still aren’t too widely used just yet, there’s now real commercial support for cast, wrought, and specialty aluminum alloys. Aluminum is special amongst other AM metals in that a high percentage of materials need specific composition tailoring just to form properly in powder bed fusion –even if they’re based on common aluminum alloys used in other manufacturing processes. This has likely helped (finally) spur more material developments in specialized aluminum alloys that have been designed specifically for additive manufacturing, like Scalmalloy and Addalloy.
It is this material expansion in a very additive-centric or specific nature that, when we extend the industry timeline out several more years, we can arrive at a conclusion –aluminum printing is key to the future of the metal powder bed fusion technology market. In an industry that will increasingly diversify in terms of metal additive process types, there will at some stage be competition for machine investment dollars amongst the expanding community of metal AM. Even though processes like metal binder jetting and directed energy deposition aren’t all that comparable from a technical standpoint, we’re already seeing some of these competitive effects as users want to explore the possibilities of new metal processes, especially those that still face some challenges with expanding their scope of use in metal powder bed fusion.
Aluminum printing is almost entirely based in powder bed fusion technology today, and with the rise in process-specific aluminum materials, is likely to become a highly defensible zone for this specific group of metal AM technologies to play in. Development of a good solution for bound metal deposition or metal binder jetting of aluminum is probably an inevitability at this point, with Stratasys, Desktop Metal, ExOne, and potentially several others already working on it to some degree. However, there has no doubt been a shift in what we’ve seen many of these bound metal companies begin their commercial operations saying (“print in more materials like aluminum!”) and what they’re actually building businesses around several years in (steels). And even if some aluminum materials become commercially viable in terms of bound metal sintered parts, aluminum powder bed fusion materials are already moving into uncharted territory with alloys based on rare-earth and transition metal alloying elements.
This leaves powder bed fusion not only as the key –and possibly sole –additive technology for aluminum printing at scale, but also as a tool which can unlock new capabilities with aluminum parts not found using traditional methods like casting or machining. Thus, powder bed fusion and aluminum may be strongly linked well into the future as a major opportunity with benefits and capabilities that no other manufacturing technology –additive or not –can match. This will certainly aid in building business cases in aerospace, and in the future possibly other industries.