By Maxime Legrand, Innovation Manager, AMEXCI

AMEXCI’s previous Quarterly Review for Q1 was focused on the hot topic of spare parts in Additive Manufacturing (AM) and how to manage decentralized production. We continue our Quarterly Reviews by shedding some light on metal technologies, presenting past and recent developments while taking a step back and putting these new innovations into perspective.

In the 80s, additive manufacturing started as a polymer technology. Around 15 years later, it was the turn of metal additive manufacturing. Laser Powder Bed Fusion (LPBF) technology, also known as Selective Laser Melting (SLM), from the first company to commercialize such printer, started its journey. The first steps were focused on producing high quality parts with high density. The aerospace and medical industries were the first to see the potential in this technology, and 10 years after its debut, around 2010, the first implants and flight certified parts were being released.  Lima Corporate was already producing hip implants in 2007, and GE Aviation certified its famous nozzle in 2012 (see pictures below). These two examples focus on lightweight components and customization possibilities, two strong value adds for AM in general.

Other Metal AM technologies developed along the years. The development of Metal Binder Jetting (MBJ) started already in the 1990s and is now used for fist-size components production at higher volumes – even though, for the moment, it remains confidential compared to LPBF. Still, it progressed quickly in the 2000s alongside other central metal AM families such as DED (Directed Energy Deposition). DED gathers sub-technologies such as Wire and Arc Additive Manufacturing (WAAM) based on welding techniques, and Laser and Metal Deposition (LMD), well-known for repair solutions.

Productivity is not only a result from the number of lasers
Today LPBF has matured, and the trend is slowly shifting. While the technology focuses on productivity, the machines are getting larger and equipped with more lasers. The investment cost increases due to this development; still, the machines provide the user with more productive additive manufacturing processes. Dual laser machine is now becoming a standard solution proposed by machines suppliers such as AddUp, Farsoon, Renishaw.  Some companies are taking this race quite seriously, like SLM with its 12 laser machine and Velo3D with 8 lasers. Increasing the lasers brings in more challenges such as cooling rates and complex stress management. Companies like Seurat is exploring area printing and trying to overcome such challenges.

There are other ways currently in development to improve the machine printing speed. For example, AMEXCI is part of the European funded project InShaPe, which investigates the potential of beam shaping by changing the laser spot size, enabling faster scanning speeds. This could be an opportunity to print faster, while still being able to print fine features with for instance good contour parameters.

Increasing the layer thickness often means increasing productivity, this can be done by using different lasers. Increasing energy transfer is possible through higher laser power and tailored laser wavelength. We have seen green lasers for copper printing. Essentium, a polymer printing company, is partnering with NUBURU to develop a new machine equipped with blue laser. This would open the door to a more efficient use of energy as it increases the energy absorption for some metals.

Productivity, however, is not only about the machine itself. Today’s emerging technologies are supplemented with new tailored automated solutions. For example, BMW, just announced its new lights-out factory with a fully automated supply chain. These kinds of full automation solutions are slowly appearing, and we expect them to become mainstream in the coming years, as digitization projects continues. They are essential steps in technology development and good examples of merging future technologies.

Productivity topic is not only linked to LPBF technologies. In Coldspray, Titomic is working on automatizing their coldspray process for mould reparation from the scan to the repair. The current missing steps are automated loading and unloading as well as polishing the moulds. Another company, is trying to depose material faster and reached an impressive deposition rate of 18kg of titanium per hour.

In metal binder jetting area, the focus still seems on the 3d printing systems themselves. Most of the recent news concerns new, more productive systems. Also on the material side to make cheaper powder or more dense powder bed. Not much is shared about the depowdering or sintering step, which are critical steps in this process. HP machine, promised for 2021, is still in theory planned for late 2022.

Looking beyond the printing step, challenges such as outsourced heat treatments, lack of refurbished plates to launch the job, lack of skilled operators, especially for data preparation. Identifying your right source of productivity improvement is mandatory, and tools from the conventional industry already exist and works well, so don’t hesitate to get the best practices of these “classic” technologies.

The trend of making metal AM more accessible
One key characteristic of metal printing is the high investment costs. The industry has started to look into how to tackle that issue and make metal AM more accessible. One clear trend to drive the accessibility of metal AM forward is the booming metal filaments for Fused Filament Fabrication (FFF) printers. These technologies are provided by Nanoe, Ultimaker, BASF, and Markforged, among many others. Polymer printers are way less costly than their metal counterpart, making them attractive. Going away from FFF, Headmade is using SLS and its high productivity to produce metal parts, which seems promising.

The back side of the medal being that these technologies are producing green parts which have to face the feared step of debinding and sintering, which can lead to lots of accuracy issues and cracking. For the time being, those technologies mostly focus on prototypes and tooling.

Prominent use cases in the past months
Technology development and productivity pave the way for new innovative products. One of the more prominent metal AM use cases in the first half of 2022 is the HYPERGANIC part. Hyperganic is using an AI based design software to produce aerospike rocket engine that was printed by EOS. Another proof of the metal AM maturity and use of metal AM parts comes from Boeing, which has used over 1000 AM parts in one satellite.

Figure 1, source: Hyperganic

Conclusion
The focus on metal AM is still mainly on L-PBF where the shift towards more productivity is continuing. More accessible systems, like extrusion-based technologies are gaining more momentum even though those systems are still quite limited, with a focus on prototyping and tooling.

About Maxime Legrand

Maxime works as Innovation Manager at AMEXCI and has seven years of experience in additive manufacturing, mainly focusing on polymer technologies for multiple industries. Please get in touch with Maxime and the Innovation team for any questions or inquiries.
Contact: maxime.legrand@amexci.com