In a previous article we’ve explored at a high level the various types of Additive Manufacturing (AM) that are being used in industry. One of those technologies, Direct Energy Deposition (DED) will be looked at a bit more closely today.
As a refresher, the DED process uses a powder stream and a laser to melt metal alloy powder layer-by-layer until the build is completed. This can be from the ground up or applied to a pre-existing part. Think of it like a traditional plastic 3D printer, that uses a powder stream instead of a plastic filament and a laser that melts the material instead of a heating element.
But, is a DED machine right for your manufacturing process? Let’s explore some positive attributes as well as some key considerations needed to thrive with this technology:
1. Hybrid/Legacy Bridge
DED is particularly useful when considering hybrid machines that can function as a traditional CNC but also include some of the benefits from an additive process. The additive function acts like just another specialized tool to enhance the construction of the part. It’s like getting the best of both worlds in regards to Additive and Subtractive Manufacturing. Full parts can be made with DED but its real strength is its ability to be built on other structures.
DED’s flexibility with hybrid systems helps bridge the gap in capability, especially for shops not interested in committing to a full-time additive machine or which are hindered due to the cost of a new machine. In certain instances, legacy subtractive machines have been converted to hybrid machines without much sacrifice to either process.
2. Safety Considerations
It’s important to note that there are numerous safety requirements that must be adhered to in order to keep DED equipment, material, and personnel safe. The metal powder is a fine particulate that requires a respirator any time the powder is exposed to open air. Besides preventing airborne powder from being breathed in it also poses fire and explosion risks as powders are flammable, some extremely. Powders also need to be handled within an anti-static environment. Altogether, this means space must be dedicated to this process and a form of enclosure built around it.
3. Part Repair
With the powder melted at a focal point of the laser, very little of the powder is lost in the process eliminating a need to sift like with powder beds. The advantages of this method appear in its ability to repair existing parts or complete additions where a structure would save material by adding on rather than cutting it away from a larger starting piece. It’s near impossible to try and work on an existing part on a powder bed, but this is made possible with DED.
There are some cases in extreme environments where part repair is almost a necessity. Some operations in remote locations actually use additive machines to repair their parts or create new ones because it is faster and less costly just to make them on site. For example, NASA even experimented with trying to use moon dust to achieve similar results. Though with the lack of moon dust available on Earth and on the International Space Station more realistic materials will have to suffice for now.
4. Rough Surface Finish
The limitations of DED focus on the build’s exterior which has a very rough surface finish when a build is completed. This is partially mitigated with a hybrid machine as the CNC portion can add a smooth, finished surface. While a DMLS created part can be viewed as passable without a finishing cut, a DED created part almost makes that finishing process a necessity.
Flexibility is making this emerging technology an attractive choice for certain manufacturers. If certain considerations like safety and what can be built with this process are adequately controlled, the DED process can give manufacturers a significant advantage in the right situation. Whether it’s converting a legacy machine, investing in a hybrid one or incorporating a dedicated DED machine this process can leverage small changes into huge potential.
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Tech Tuesday is a weekly series by TechSolve designed to help manufacturers keep up with emerging technologies and identify ways to translate them into their own manufacturing environments.