High-Speed Milling Meets Powder-Bed Additive Manufacturing

A hybrid machining center from Sodick integrates high-speed machining with direct metal laser sintering (DMLS).

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A roadblock to AM usage has been the traditional thinking of manufacturing, which requires many separate machines for separate processes. Integrating machine design, application design and IoT networking can avoid that roadblock. New hybrid manufacturing technology can help, says Masa Fukushima of Sodick.

The company has introduced its OPM250L, a hybrid manufacturing system that combines high-speed milling via a 45,000-rpm spindle with direct metal laser sintering (DMLS). Fukushima explained the machine during a presentation at the most recent Additive Manufacturing Conference. The process on this powder-bed metal 3D printer involves 50-micron layers that are grown using a high-powered, fiber optic laser. The laser sinters the metal to a 99.99 percent density, he says. The material is hardened and milled as it is layered until the height of the part is reached. 

Surface finish is one key advantage of this system. Combining DMLS with high-speed milling enables standard cutting to a 2-micron Ra surface finish, followed by a shift cut that gets it down to 0.47-micron Ra. (Rather than cutting to zero on the first layer, a shift cut leaves excess stock, enabling blending by building onto that layer and machining off the next.) It’s then possible apply lapping to achieve a mirror finish, which previously was a challenging task. 

Plastic injection molds provide a good example of integrated application design for this hybrid machine. Typically, a mold requires a cavity and core with various components demanding multiple processes (sink and wire EDM, grinding, and milling) and their corresponding setups. However, the OPM250L hybrid allows a mold to be grown as one piece with just one setup, dramatically reducing production time. Fukushima cited a mold cavity that was produced saving 63 hours, and a mold core that was produced saving 125 hours.

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