Two Australian companies are bringing innovative techniques to the world of 3D-printed metals, and their work holds exciting promise for the manufacturing industry.
Titanium seems to get a lot of attention when metals for 3D printing are discussed. But AML3D founder and Managing Director Andy Sales (pictured above) finds aluminium much more interesting.
“Aerospace companies are in fact reducing titanium used in commercial aeroplanes, not increasing. This is interesting because, in 3D printing, one of the most common metals of focus is titanium, regardless of the process,” Sales tells create.
“The aerospace manufacturing industry is currently focused on carbon fibre and special composites, which are lighter and have a higher strength-to-weight ratio. However, in terms of metals, the industry still uses a lot of aluminium. Yes, titanium is light with a higher strength-to-weight ratio, but it’s not as light as aluminium and is more problematic and expensive to fabricate. Hence, in the last few years, there has been an increase of research in high-strength aluminium.”
Few of AML3D’s aerospace clients are interested in titanium parts. Non-aluminium work for these customers — such as a recent 150 kg mandrel tool artifact printed out of Invar 36 for Boeing — tends to be on the tooling side.
As for aluminium, like any other group of materials, there are pluses, negatives and trade-offs compared to the alternatives.
AML3D’s process is based on welding: it lays down welds bead-by-bead to build a near-net shape. It makes such shapes out of any available welding wire grades and does so at a rate of up to 10 kg per hour, depending on the metal.
While cast, billet and rolled formed aluminium grades have their benefits when welded, the strength of the melted feedstock is inferior to its parent equivalent. For example, 6000 and 7000 series lose the strength they have gained through heat treatment when welded together.
“For every other metal that we additively manufacture through the arc welding process, WAM [wire additive manufacturing] is always stronger than the equivalent parent metal that is welded together. We patented the WAM process for welding stainless steel, carbon steel, titanium, nickel alloys and everything else,” explains Sales.
“That’s the basis of welding engineering: overmatching weld joint strength when compared to the parent metal being joined together. The exception is aluminium.”
Building on success
Sales had the idea for a company that uses arc welding for additive manufacturing while studying a Master of Science in Welding Engineering at the UK’s Cranfield University. Upon his return to Australia, he formed AML3D in 2014, and the company was listed on the ASX in 2020.
AML3D sells turnkey robotic production cells, called Arcemy, which use its WAM process, and operates a bureau service at its Adelaide headquarters and Singapore office, as well as offering bespoke design services and consumables.
The company has research relationships with Flinders University, RMIT, CSIRO and Deakin University. Recent collaborative projects with the latter have targeted the shortcomings of aluminium alloys as a welding feedstock.
Sales approached Deakin in 2020 due to the Institute for Frontier Materials’ work with scandium in wire and plate alloys.
Scandium is a rare earth element on which AML3D had done early research and development. It can dramatically strengthen the grain structure in aluminium when even tiny quantities are added.
It is produced in low volumes globally and is therefore expensive. Sales says a kilogram of standard grade aluminium wire feedstock is about $15, versus approximately $130 for wire with 0.2 to 0.3 per cent scandium added.
“If you’ve got aerospace-grade titanium-type prices on aluminium, it’s just not going to be commercially viable until the price of scandium comes down,” he says.
A 12-month Deakin scandium project on developing high strength aluminium alloys, supported through an Innovative Manufacturing CRC grant, will likely be extended.
Through this project, AML3D made use of software alloy models at the university and conducted testing of printed parts.
While there is the possibility of a patent in the making, there is a great potential to offer an affordable, high-strength aluminium alloy wire for in-house use creating 3D-printed structures with a resulting higher strength and sale to the wider welding consumable industry.
This is very exciting, Sales says, due to the game-changing aspect of improving weld joint parity to aluminium parent metal structures.
Work with Deakin’s IFM announced this past November involves two feasibility studies on ways to incorporate boron nitride nanotubes (BNNTs) in a composite aluminium wire. BNNTs are a novel material lighter than carbon fibre with 30 times the strength of Kevlar.
In late 2021, the manufacturing company Additive Assurance announced its first high-profile partnership. The company’s equipment found a home at Volkswagen’s Wolfsburg plant ahead of a planned capital raise early this year.
Co-founder Marten Jurg says that the company has since exported “a few other units around to other manufacturers of similar scope”; has onboarded a US-based business development manager; and is looking to hire more workers.
Jurg’s company makes sensor packages and associated software for users of laser powder-bed fusion additive manufacturing.
The optical sensors fit to the outside of a machine, looking in, and the algorithms make sense of data from metal layers as they are sintered together by high-powered lasers.
It calls its solution AMiRIS, a stylised version of “AM iris”.
Companies usually check a printed part’s integrity after a job is finished using CT scans. Additive Assurance uses long exposure spectral imaging that compares parts in process against what they should be. This detects defects and puts a stop to doomed print jobs to avoid wasting expensive metal powders and machine time.
The method Additive Assurance has developed goes back to Jurg’s time at Monash University, where he studied for a PhD and led the installation of a new Concept Laser machine at the Woodside FutureLab.
Jurg had previously studied aerospace engineering at RMIT, where he regularly used metal additive manufacturing.
“A few months after we installed the machines, started producing parts, doing test things for Woodside and various other bits and pieces, we came across some issues that were quite interesting,” Jurg tells create, saying that the reasons behind obvious faults could not be figured out — and the machine’s maker was similarly stumped.
“I went through all the machine systems trying to probe absolutely everything I could get my hands on, trying to figure out what was going on. I couldn’t make heads or tails of it.”
Attempts at finding out involved a borrowed high-speed camera — fascinating but resulting in huge files — and then long-exposure recording.
“At the time, it was just a digital SLR that we’d set up on a tripod in front of it from the machine to capture this info,” says Jurg.
“Then we’re able to give that to the machine maker, and the machine maker said, ‘Oh yeah, that’s not normal. It’s a problem.’”
Jurg realised his method could yield more than a visit from a technician, such as data on fluctuations in energy intensity and defects occurring due to reasons other than machine faults.
This eureka moment led to further work and the accelerator program at Monash University’s entrepreneurship hub. Jurg and his PhD supervisor Associate Professor Andrey Molotnikov, who is now at RMIT, registered Additive Assurance in 2019.
Jurg believes that Australian universities are overall significantly behind those in the UK and US in terms of research commercialisation but have gotten better at providing entrepreneurial training to researchers.
Importantly, he says, technology transfer offices are becoming more accepting of spinout businesses being formed, rather than more simply licensing innovations to established companies.
Another interesting thing about the present moment is the cultural effect of COVID-19 on workforces, Jurg adds. Start-ups on the lookout for top talent are in competition for software engineers with Amazon and other leading firms.
“Those big companies like Atlassian, which is saying that they’re going to hire another 5000 software engineers — that is really bad news for us. That’s terrible. There aren’t 5000 software engineers on the market, I don’t think,” says Jurg.
“What we were really encouraged by from the whole COVID situation is that we’re no longer thinking in geographic, pocketed terms, and being able to access talent, whether they be based in Adelaide or Perth or Darwin or wherever … Being able to engage with people, they don’t necessarily need to come into the office at all to be quite useful. So I think that’s the silver lining.”
Skin in the game
According to Sales, collaborations between private businesses and universities work best when each party shares the risks and rewards. Universities taking a stake in their spinouts is one way they can have skin in the game. Another is through the licensing of resulting IP from collaborations in an equitable way.
“Probably a slight differentiator with Deakin is that they are very focused commercially, and that is evidenced by previous collaborations,” says Sales.
“They realise that there’s a commercial opportunity for growth through innovation, not only for the companies they’re working with but also for themselves through sharing the IP. Typically, with joint IP, there are royalties involved, which creates a win-win scenario.”