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- What is Selective Powder Deposition?
- USE CASE 1: Bi-metallic Laser Powder Bed Fusion (L-PBF) printing
- USE CASE 2: Zero waste polymers Selective Laser Sintering (SLS)
- USE CASE 3: Binder-free solidification of ceramic or metal near net shape parts
What are your use cases?
We have been asked this question countless times in the last 3 years. Of course, this is the most “business-wise” question one can ask about an innovative technology like ours.
For us, this question has typically been hard to answer because we feel our technology can be used in such a variety of use cases. Just think about how many industries handle fine powders! Potential exists in all those industries that, at some point in their processes, would benefit from selective powder deposition (e.g. dosing, handling, coating …).
Today we decided to focus on 3 use cases primarily. Each use case is backed up by a number of industrial applications which we can’t describe with too many details due to confidentiality reasons. We can only share, as examples, some of the applications that are already publicly available.
What is selective powder deposition?
First things first, what has Aerosint actually invented?
To understand what selective powder deposition means, it’s easiest to compare what we do with what a 2D printhead does: it prints a desired pattern with inks. Well, what we have developed is a device that can achieve similar results but with dry powder voxels.
Our selective powder deposition device can create thin multiple-powder layers based on a digital process which is proprietary to Aerosint. Currently, we handle 2 powders simultaneously. But no technical limitation prevents us from scaling the process up to more powders in the future. The beauty of our approach to powder deposition is that it works with a wide range of polymers, metals and ceramics.
A multi-powder layer (as the ones shown below) is the starting point for the 3 use cases described further in this article.
Use case 1: Bi-metallic Laser Powder Bed Fusion (L-PBF) printing
Once you have a multi-metal powder layer in a L-PBF printer, the only remaining challenge to overcome (and it’s not a small one!) is to identify the right laser scanning strategy to fuse together 2 compatible metals. When that is mastered, the opportunity to use a L-PBF process to print bi-metallic parts is unlocked.
This is one use case we have been working on since early 2018 in partnership with Fraunhofer IGCV. At Fraunhofer IGCV they have been working on multi-metal printing for quite a few years now. Therefore, partnering with them felt natural for us as we could benefit from their extensive material and process parameter development expertise. As part of the collaboration, our technology was integrated into a L-PBF printer from the Fraunhofer IGCV Institute. Trials were made to validate that powder deposition could achieve the printing of bi-metallic parts.
More recently we have partnered with the German L-PBF printer manufacturer Aconity 3D to bring our technology closer to commercialisation. Rumours are that something will be announced at Formnext this year (2019) …
Bi-metallic printing could benefit all applications where there is an advantage to have, inside the same part, areas with different properties like conductivity, ductility, hardness, lubrication properties, cost… Some publicly known examples of bi-metallic applications are conformal cooling channels for injection moulding tooling to improve the moulding process productivity or wear-resistant toolings consisting of hard outer metal and a ductile inner metal.
Use case 2: Zero waste polymers Selective Laser Sintering (SLS)
This is one use case we feel could significantly improve the material efficiency of existing SLS systems. Current SLS printers typically waste 30% up to 85% of the polymer powders integrated in the process. This results in a significant cost for the user but is also an environmental concern because the recycling of this waste remains a challenge today.
With a process like ours, support powder can be chosen to be inert to the heat in the chamber (no material degradation currently resulting in material losses). The support material can fully be recycled resulting in significant powder savings.
We have integrated our powder deposition technology in an SLS printer (EOS P350). We are currently in the process of validating this use case by producing small polymer parts.
In parallel, we have established relationships with the Solvay Specialty Polymers Group as well as with the Belgian Sirris Research Institue who support us in this use case.
Various companies have also approached us with the request of printing dual-polymer parts or even with the request to integrate a conductive material inside a polymer part. Those are interesting applications we will investigate in due time.
Use case 3: Binder-free solidification of ceramic or metal near net shape parts
What if it would be possible to combine the geometrical free-form benefit of Additive Manufacturing processes with the advantages of widespread classical powder densification processes?
The innovative process we are testing for near net shape ceramic or metal printing is the following:
- Using Aerosint’s selective powder deposition device to deposit Ceramic/Metal in the desired shape surrounded with a carefully selected support material, effectively forming a near-net-shape mould while printing.
- Densification step through mechanical compaction. This results in a dense green part (includes little to no binder depending on the powder type).
- Solidification of the green part in a traditional furnace.
The benefits of this approach are that it should work with a very wide range of powders typically used in traditional powder manufacturing, it doesn’t rely on the use of binders, and uses densification and solidification processes that are widely used in manufacturing.
Feasibility of this approach was demonstrated with glass and alumina. Over the next months, we will be testing more materials, including metals, to further demonstrate the benefits of this unique new process to produce parts.
Multi-material parts could also be fabricated with this process, including functionally graded materials (FGM). FGMs are one of the “holy grails” of Additive Manufacturing and their production is being investigated by numerous research-driven organizations we have been in discussion with.
To sum-up
Bi-metallic, zero waste SLS and binderless ceramic/metal parts shaping are the 3 use cases for selective powder deposition we, today, consider being the most promising for selective powder deposition. They all lead to a great number of interesting applications we want to further investigate with our existing and future partners.
Other use cases, even with more potential, might emerge in the next weeks/months/years. If that’s the case, we will make sure to be lean enough to not miss-out on something big!
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