Joule printing six-inch part cracking due to thermal gradients

Tom's recollection of Digital Alloys' development challenge ~15 months before the lecture: thermal gradients caused cracking on six-inch parts; resolved by increasing print speed (printing on hotter metal).

Tom: When they started doing this about fifteen months ago, the big problem was keeping the heat in the metal. They weren't getting the diffusion, then we were getting porosity in the final layers. It amazes me that you can have a machine that goes that fast, but they just sped up the machine to go faster, and they solved the problem. But you're going to have some problems with residual stresses eventually. They could not make that as a six-inch by six-inch part without getting cracks.