Hartford, Conn. Pratt & Whitney is flying dozens of parts in aircraft engines manufactured through the 3-D printing or “additive” process. Asked how these parts can endure the thermal and dynamic stresses required of aviation parts—when they are laid down one layer at a time and presumably have seams or a “grain” afterwards—company chief engineer for manufacturing Lynn Gambill told Air Force Magazine each layer of a metal part is laid down before the layer beneath it has cooled. The layers bond together seamlessly, resulting in a homogenous part; a single crystal “with no grain.” The secret, she said, is in Pratt’s metallic powder, part of a proprietary process. The technique is also capable of producing parts within parts at the time of manufacture, such as a gear free to move within an outer part. “The powder serves as a placeholder” to separate the inner from the outer parts, Gambill said. The unused powder is removed after printing, leaving the inner part free to move. Unused power is also reclaimed for re-use, reducing the cost of material. The 3-D process saves material and money, and allows prototyping of parts that can speed the development process, Gambill said.
While some of the Air Force's newly announced changes will happen quickly, it may take most of Chief of Staff Gen. David W. Allvin's tenure in the job to accomplish the rest, he said in a Brookings Institution event Feb. 28.