Laser sintering is, in fact, being used for very small production quantities in aerospace and high-end automotive applications, such as race cars. Dave, you hit the nail on the head--one reason is for very small volumes where the cost of tooling is huge and amortizing it over a few parts make them very expensive parts, indeed. It's also being used to make the pattern for the mold in plaster cast aluminum parts, as a substitute for die-cast parts. Stay tuned--a January feature article looks at low-volume manufacturing with AM techniques, including LS.
My point was intended to assert that a means of forging without needing a forging die, strictly a noncontact forging mechanism, such as a bust of laser energy to create a shock wave equivalent to the forging impact. Probably it would not be competitive beyond relatively small production runs. My thought was that if an approximation of a hammer forging process could be developed that would be the way to get 100% density and a desireable grain pattern.
In short, it would wind up being a fundamentally different technology from anything that we have presently.
Yes, we are also using additively-manufactured (AM) patterns for investment-casting of various copper and nickel alloys, as well as stainless steel. Another point to consider is that AM is the only means of producing complex patterns effectively. Case-in-point, there are numerous articles being released on the internet discussing the "world's lightest material," produced using an AM pattern.
Doug, can you tell us what kinds of parts you're making using AM for investment casting? If they're for automotive, medical, aerospace or industrial applications, we'd like to find out more about your application. Please send me an email if you'd like to share some information.
@Doug: Actually, it might be more accurate to call the technique used by the group at UCSB to make the ultralight metallic microlattices which have recently been seen balancing on the head of a dandelion "subtractive manufacturing." First, they made a pattern out of a photocuring polymer, then they coated it with electroless nickel, then they etched away the plastic. It's a fascinating approach. I would never have thought of using electroless nickel plating as a stand-alone structural material!
I agree with you that additive manufacturing is a great way to make patterns for castings - and not just investment castings, but also sand castings.
What kind of rapid patterns are you using? When I worked in investment casting 5 - 6 years ago, we mostly used QuickCast patterns. These are epoxy patterns made using a stereolithography process. What makes them unique is that they have a cellular structure, which allows you to burn them out with a minimum of ash and without cracking your mold. A disadvantage is that they are not autoclavable, so you can't take a QuickCast pattern and put it on a wax sprue. We also used wax patterns made on a ThermoJet 3D printer. They were autoclavable, but the dimensional accuracy was not as good.
Given how quickly things have been developing, I wouldn't be surprised if there have been new developments in the past few years.
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