SmarTech Publishing recently released its first report on aluminum alloys additive manufacturing. During the research phase, several interviews were conducted with leading AM and aluminum market operators and stakeholders. All the information collected was used – in combination with SmarTech’s material and hardware database – to build the 10-year projections and forecasts which on adoption of aluminum in AM. While the quantitative information collected was used in the report, some of the qualitative information acquired during the interviews is presented below, as major aluminum AM market operators discuss the trends that will see aluminum become one of the most sought-after materials in AM.
Al, from prototyping to production
One reason that aluminum is so interesting is that 3D printing is transitioning from a prototyping to a higher batch production technology. Manufacturers are looking for materials that are both light and more cost-effective than titanium and nickel superalloys like Inconel. While Aluminum AlSi10Mg is the most commonly used material today, manufacturers are looking into new, AM-specific aluminum alloys. “Aluminum AlSi10Mg is the most used material at Materialise,” confirms Ingo Uckelman, Technical Manager 3D Printing at Materialise. “Most aluminum AM applications today are prototyping applications”. Peter Mercelis, agreed. A former director of Applied Technologies at 3D Systems, Mercelis left in February 2018 to fund a company investing in the future of medical devices. “I haven’t seen that many volume manufacturing applications yet – he explained – but it’s just a matter of time before that happens. In our case, it’s probably the third or fourth material today, behind steel alloys and nickel-based alloys. We do see a growing trend for aluminum.”
Additive Industries, another major PBF metal system manufacturer confirmed through a spokesperson that the company is seeing growing demand for aluminum alloys because of its excellent balance of weight, material cost and characteristics. “Aluminum is our primary material and we do see a growing trend toward larger batch production,” confirmed Martin Kappler, Global Manager Metal Powder, 3D Metals & Services, at SLM Solutions. “Just think about adoption by the automotive industry. Since the number of parts they require is much higher, they require bigger systems and larger build chambers. For this reason, I think aluminum, combined with steel materials and titanium, will become one of the biggest materials in additive manufacturing.”
According to Heraeus, a major AM powder manufacturer, aluminum adoption will grow significantly as prices of atomized aluminum powders will drop significantly over the next few years. “There are two reasons,” Dr. Reiner Meisel, AM Product Manager, explained: “Number one like it is valid for all material, AM technology is becoming more and more attractive for the industry. Therefore, a price drop has already started. But also, especially for aluminum powder, there is a massive over-capacity which is caused by a drop in demand form the solar photovoltaic industry.” While this is true for currently available aluminum alloys, major aluminum manufacturer are looking into developing new AM-specific aluminum alloys.
Cracking the code with scalmalloy
Several challenges still need to be overcome before aluminum AM becomes a truly viable option for production. “The challenge for laser-based technologies is exactly in further expanding the range of alloys that can be currently processed,” a spokesperson from Additive Industries told us. “Many alloys have been developed for other processes such as casting and can suffer from effects such as hot tearing whilst being processed in AM. This is why Additive Industries now offers Scalmalloy, which is a high-performance aluminum alloy developed especially for AM.”
The need for AM-specific aluminum alloys is highlighted by Arcam CEO Magnus René. The Swedish EBM hardware system manufacturer (that also owns AP&C, a leading AM powder manufacturer) does not currently offer support for aluminum but that could change if new alloys – such as Scalmalloy – become more widely available. “More or less all materials we’re using these days in additive manufacturing were not created for additive manufacturing. They were invented for casting or for other applications,” explained SLM Solution’s Martin Kappler “Likewise most aluminum alloys used in AM today were originally invented for casting,”
Andrea Pasquali, General Manager at Italian leading metal 3D printing service bureau Zare, has already built a number of case studies on scalmalloy AM. Zare is an official partner of APWorks on scalmalloy development. “[Scalmalloy] is ideal for space and aviation applications, I don’t see it as having more “day-to-day” applications at this time – he explained. “It is mainly an issue of costs, both in terms of raw materials and production processes. It is quite a slow production process compared to traditional aluminum. At the same time, it registers mechanical performances that are double compared to standard aluminum alloys such as AlSi7 and AlSi10. It suffers a little at high temperature but it’s great challenger to titanium.”
“The demand for high-strength, lightweight alloys in aerospace is significant but today we still face some technical issues with current aluminum alloys,” said 3D Systems’ Mercelis. “We obtain cracks during printing because aluminum is a very high thermal conductor. This is a good thing for heat exchange on one side but on the other, that also gives issues in terms of reflectivity of the laser. So a very small amount of the laser is being absorbed by the material itself. Furthermore, the very high cooling rate during the production of these aluminum alloys causes cracking. We’re working on improving the technology itself in order to be able to make it crack- free and fully dense parts using these high-strength alloys.”
“Aluminum is very reactive with oxygen,” added Dr. Meisel. That means you need special equipment to produce it and handle it. What we really need to do to tackle this and other challenges is to cooperate and to work on the standardization of additive manufacturing and AM metal powders. Today we are designing everything around the powders: we are designing how a powder should be packed. We are trying to set up standards for it. We are trying to set up how a material has to be characterized. Today we are limited in designing how powders are handled before, during and after the process. In the future, we will design the powder itself to provide the desired characteristics for specific products and parts.”
Hitting the road. And the sky
Many believe that possible adoption from the automotive segment for part production will drive aluminum alloys to become the most demanded materials in AM. However, that will take some time still. “We definitely see an interest from automotive industry but we still see it primarily for prototyping,” 3D Systems’ Mercelis explained. “It is still very hard for additive manufacturing to be economically viable. There are some exceptions but most of the requests from automotive are still for prototyping. As the productivity will increase over the coming years, that may change,” he concluded.
Additive industries already see scalmalloy as a viable option for production parts. Mr. Renè agrees. “In both aerospace and automotive the most relevant application for AM is sub-assemblies. Those are the parts that it makes sense to 3D print today. Eventually – when the machines will permit it – larger parts will likely be 3D printed in aluminum rather than titanium. There may be some long-term applications in automotive. But to be really competitive in automotive, we have to be very much efficient. The advantage of aluminum – he concludes – is low specific weight. So, aluminum alloys are very interesting everywhere weight is critical. And this means aerospace. This also means automotive in some special cases.”
Toyal recently entered into a partnership with APWorks – the Airbus owned company that first optimized scalmalloy for AM – to also become a producer of the high-performance aluminum alloy. “We’ve identified three market segments,” said Fabrice Morvan, Market Development Manager at Toyal. “One is machine makers as they move large quantities of material. We are also speaking with additive manufacturing specialist and service bureaus. The third target is to work directly with the specific tier one suppliers to the automotive and aerospace industry. “We are in contact with companies like GE, Saffron, and we are mostly focusing on aerospace. Also, you must consider that our core business activity, which is not related to additive manufacturing is to produce metallic pigments mostly for the automotive paint industry. This means we enjoy excellent relationships within the automotive field. Toyal Japan is a definite market leader in the field of aluminum, with very strong ties to with Toyota and Honda. We expect that will open doors in the future.”
Making the best of all this
What are the main benefits driving adoption of aluminum in AM? Often it’s not only about cost-effectiveness and lightweight. “Weight saving is an important aspect but you have that with titanium too. In many cases it’s about thermal conductivity, said Mr. Mercelis. “The reason we got into AM is for the overall mechanical properties of scalmalloy,” added Mr. Morvan. “It’s one of the first alloys which was specifically designed for additive manufacturing and it’s also one of the first aluminum alloys for AM which offers highly desirable mechanical properties.”
The benefits of aluminum in AM can be numerous and depend on the application. Aerospace adopters, for example, use the material properties of aluminum, with the design freedom of AM, to produce components that are considerably lighter than their conventionally machined equivalent. “The aviation and space industries have made this transition,” says Mercelis, “Now they are thinking in terms of how to design for optimal function and then they come up with valid applications. In automotive, on the other hand, you don’t really see that transition yet. So it’s more about cost-effectively replacing current parts with AM and then in many cases, the answer is no. And as the productivity is not there yet, they will keep hesitating to shift their thinking to how can I design for optimal function instead of optimal manufacturing.”
A binding resolution
On very interesting opportunity for the medium to long-term future is represented by the introduction of metal binder jetting processes that could be feasible for higher batch and even mass production. HP, Desktop Metal, Stratasys and other companies are moving in this direction. “I think that’s going to be the future of AM production,” said Zare’s Andrea Pasquali. “In particular we really admired Desktop Metal’s vision for the Production System. Today at Zare we use powder bed fusion systems however we are convinced that in the long terms future the majority of AM production will be carried out with binder jetting technologies. We have already asked to work with both Desktop Metal and HP on the upcoming systems and to help them with material and process development. It is going to take a couple of years and I don’t think these systems will ever replace powder bed fusion as much as expanding AM capabilities beyond the current limits in terms of productivity.”
It may still take several years before the technology becomes available for aluminum powders. “I think it is interesting because also it’s very fast,” said Dr. Meisel, “but then yes you have to manage it as you would in MIM, and to be honest that is not going to be very easy. Sintering aluminum in a furnace is not easy and there may be issues with using binders containing oxygen. This may be the reason why MIM aluminum is not so popular. I’m sure this is something we should investigate because discussions and information sharing bring about new ideas.”