When people think of additive manufacturing (AM), they usually think of 3D printing. Of course, 3D printing is an extremely innovative technology and is at one of its most exciting stages of evolution right now. However, it does have its limitations -- in size and the applications for which it can be used.
GE is working on an AM method to address those limitations. It is using a spray paint technique known as cold spray (or sometimes 3D painting) that builds upon metal surfaces. Metal powders are sprayed from a nozzle at extremely high velocities to add material to metal objects. During the process, a strong bond is created, and only a minimal amount of heat is transferred. As a result, the process is safer than welding and still results in a durable end product.
Researchers repair and build upon metallic parts by spraying metal powders at supersonic speed. (Source: GE)
Anteneh Kebbede, manager of the Coating and Surface Technologies Lab at the GE Research Center, said in a press release:
In addition to being able to build new parts without welding or machining, what's particularly exciting about cold spray as an innovative, 3D process is that it affords us the opportunity to restore parts using materials that blend in and mirror the properties of the original part itself. This extends the lifespan of parts by years, or possibly decades, ultimately providing improved customer value.
Cold spray, a method invented in the 1980s, has been used mostly in military applications. Until now, there was no commercially available method for utilizing this technique. GE's process makes it possible for companies to use this technology to extend the lifetime and quality of their products. In the future, this may be a common method of repair for many different facilities.
@Plantex: Although I have no experience with this process, I would assume it is similar to the old process of spray on Metallizing, in which you build up a surplus and then grind or machine to finish requirements. This was commonly done to auto crankshafts back in the sixties. The real advantage here is that the process is cold so you reduce the possibilties of distortion in adjoining features. I am curious what sort of prep is required prior to application and how overspray is handled.
Excellent post Cabe. I am definitely not familiar with this process so I really appreciate the "heads up". I applaud any technology which makes "on-site" field repairs possible. As a result of your article, I will put this technology on my list on items to follow. I retired from GE and have "spies" still at the R&D group so maybe I can get additional information through that source. Again, thank you.
Plasma spray was expensive in the '70s. Building up shaft cost more than a new one. "Temperature" is 3-D Kinetic Energy. This sounds like semiconductor industry "ion implantation". Velocity is 1-Dimensional "Temp" so it's welding/embedding atoms.
The old Wright whirlwind and cyclone radial engines used (I think) in the DC3 era airplanes had one single crank-pin so all 1800 or so ponies had to release their power through that one crankshaft. They were very difficult to make and when worn-out were routinely thrown away - until the 60's or 70's when a process was developed to allow metal to be weld-deposited onto the worn area. Subsequent heat treatment and metalurgical analysis has kept these old engines air-worthy and many are flying today in remote areas. Imagine the number of other critical components that could be repaired and/or improved using this cold-spray process. Great article.
Cadman, this process is probably a lot more expensive and complex than most welding projects, so I doubt very much that any welders will be displaced. Besides that, who would be better qualified to apply this technique than skilled welders?
Yes, this is an interesting article. But it leaves out a bit of information, such as just how fast is that stream of particles moving, and how big is the stream. Many years back I had acquired a device that was claimed to be able to build up metal surfaces by spraying metal particles entrained in an inert gas stream and heated by an electric arc. I sold it at a profit and have no idea how well it worked. But that was clearly a high temperature process, based on the plasma heating part.
I am aware that explosive bonding of metals has been around for quite a few years, but that process involves both high velocities and quite a bit of force. So I am wondering if we coulkd get a few more details about the process.
And I think that there is probably a safety concern, since a cloud of the metal particles that don't bond must certainly be something to avoid breathing. Even the non-toxic metals would not be good to inhale. Sort of like the hazards associated with other nanoparticles, I would suspect.
Interesting idea, was aware of Plasma spray to add coatings but not cold spray.
I am also curious about the bond strength (in comparison to welding processes). Deposition rates and cost of materials is a factor as well as the cost of the equipment (and required surface prep before coating).
Not being a naysayer, but I wonder also about the precision of application (thickness, overspray etc.).
I just wonder what the limitations are. Small cracks, big cracks? We used to repair robotic welding arms. They were not an easy fix. If this makes it easy...great. Still might put some welders out of work...cause that was the only reason we had one.
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