About 20 miles east of Pittsburgh, the former heart of the nation’s steel industry, a small company called ExOne is churning out a new generation of stainless steel boat propellers, oil pump parts and door knobs. Manufacturers are increasingly using 3-D printers, made by ExOne in Irwin, Pa., to make production parts, rather than just product prototypes. But there are no clanging hammers, wheezing presses or even computer-controlled milling machines. Instead, a dozen 3-D printers quietly stitch together industrial parts by meticulously spreading hundreds or thousands of layers of powdered metal onto a canvas until they form three-dimensional shapes.
3-D printing will remake U.S. manufacturing