@NiteOwl_OvO: I agree with you that the best thing about this technology is the ability to prototype. You could make a part like this as a forging or as a casting, and get much closer to net shape, at a much lower cost, but you'd have to invest in tooling. You could also weld the part out of titanium plate. That wouldn't be cheap, but it might be chaper than 3D printing, at least for now.
I don't know. It looks like they are removing 30 to 50% of the material they added in the final machining process. A lot of expensive chips on the floor, plus machining cost. With casting, even in sections, the waste would be very low and the final machining would be minimal. The sintered powdered metal flavor of AM would also waste less and might reduce or even eliminate final machining, but takes a lot more time.
The best thing about this technology is that you can go from design to development to testing to manufacturing very quickly. If demand out paces your capacity, you could shift to other higher volume production methods. This would be perfect for custom part production.
I think JimRW nailed it. The big deal isn't just how much material must be wasted before this technology becomes viable--it already *is* viable because of what material is being wasted and how much it costs: incredibly expensive titanium. That's why various methods of building parts from titanium are being used that don't include machining, or only include a small amount of post-processing, such as AM in different flavors, and powder metal (PM) methods. The second major factor is size of those parts, the fact they are structural and must meet high performance standards, and the difficulty forging & machining them. Good point about control--I don't recall that mentioned by the folks at Sciaky but it does seem intuitively obvious.
Aerospce parts are high value and low volume. Raw material costs for Titanium alloys can be $35/pound and more so reducing the volume of chips made makes great economic sense. As WilliamWeaver points out, a 300# part can start from a 10,000# blank, making $339,500(est.) worth of titanium chips.
Forging such large titanium parts also has issues, requiring very specialized, high tonnage machines, of which there are not many, along with finished machining and past heat treatment(s).
These parts are also highly engineered with the fabrication processes needing to not only achieve the desired net shape, but also the desired strength and performance in critical areas. I wonder if this build up process allows more control of the finished material properties in specific areas of the finished part, since they are effectively working with smaller "building blocks" of material.
I guess it depends on the material. Titanium is pretty tough to machine compared to say aluminum, so it might make sense to remove up to 80% of the material with aluminum while titanium maybe only 40 to 50%. If they cast the part in section, since it's large, and welded the pieces together, then only minimal machining would be required.
I suspect that heat treating and stress relieving would be required for a lot of parts made using this method of additive manufacturing. With the exception of the bottom-most substrate, the completed part is basically made up of layers of weld. I would think warping and stress fractures might be a problem.
I was blown away by how fast that machine could weld, though. That electron beam welding gun is awesome!
My thought was that it might make sense to either cast or drop forge the part. You could also cast smaller pieces and weld them together and then do the final machining, but hey that would be old school. Don't get me wrong, I love additive manufacturing and I can't wait for this technology to become mainstream. Just think what inventors can create with machines like that. Glad to hear that Lockheed is involved. Very exciting...
I'm going to guess that the additive technology makes sense when the traditional "subtractive" CNC technology needs to remove more than about 50% of the source material. We've been watching NOVA's Battle of the XPlanes for a few years in our materials class and "Bulkhead 270" for Lockheed's F-35 JSF is a particularly intricate component made of titanium alloy.
The finished 300 lb part is whittled down from a 5-ton slab of the alloy (10,000 lbs). So grinding 24/7 for weeks to obtain a part that is only 3% of the starting slab sounds like this additive method would be a smart route if the resulting material properties are appropriate...
Nite_Owl, thanks for your comments. Sciaky says it's working with Lockheed to develop this technology further, but it is being used in real aircraft production environments, not for prototypes. For some OEMs, the ability to make parts this big in one pass at a reasonable rate of speed outweighs the value of making much smaller parts at a faster speed and bolting them together.
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