Simplified Intricacies
Figure 2: Additive manufacturing, or 3D printing, produces complex shapes with one process, creating sand molds for casting (top), for example, or finished metal parts (bottom).On the one hand, ExOne's additive manufacturing processes are highly controlled in that they rely on sophisticated mathematical models to render designs and configure the most efficient way to nest parts in the build box. All software is developed in-house for the metal machines, Wood says, and ExOne has a relationship with a university to create the software for the sand machines. The machines could run for days without intervention, Wood notes. As mentioned, precise control of print head location is necessary, and also rolling out the fine powder layers requires extreme precision to make those layers flat and uniform.
On the other hand, there is much of the process that could still be automated. "Additive manufacturing is really in its infancy on automation, especially on the material handling side," Wood says. "There's still a lot of potential for controls."
For instance, one build process could fill a build box with literally thousands of small cores. Each of those cores — which at this point are so fragile as to be easily crushed — must be removed by hand and the excess material blown off by a hand tool. They are transferred by hand from box to box for sintering and infusion. "We could really automate the removal of the cores," Wood says, noting the time that could be saved in the process with automation.
As it is, ExOne continually looks for ways to speed up the process. Considering the hundreds or thousands of layers used to build any given piece, saving just a second off of each layer makes considerable difference. "There are about 250 layers in an inch," Wood notes. "So we look at things like how to save 2 s in a layer." The latest M-Flex machine achieves build speeds of 30 s per layer, compared with previous build speeds of about a minute and a half per layer.
"We've made tremendous strides in 3D printing in the last decade, and what our machines can do today is simply remarkable," said Dave Burns, president of ExOne. "We are printing engine castings for helicopters and replacing broken pumps in oil fields in days — not months."