Why the Future of Additive Manufacturing May Be Hybrid Manufacturing

According to DMG MORI’s Dr. Greg Hyatt, additive and subtractive working in tandem is better than either approach on its own.

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Additive manufacturing is akin to “building a ship and the bottle around it at the same time,” says Dr. Greg Hyatt, senior vice president and CTO at DMG MORI Advanced Solutions Inc. AM makes it possible to combine complex assemblies, build intricate forms and hollow structures, but without a way to address the areas trapped inside the part, there are limitations to its application.

The issue of access is one reason why DMG MORI chooses to offer additive manufacturing capability in the form of hybrid systems. Its hybrids are machine tools that integrate a laser deposition head fed by a supply of metal powder. Because deposition does not require a powder bed, difficult-to-reach areas can be machined as the part is built up.

But apart from the ability to interject machining cycles into the additive build, a hybrid approach offers other well-known benefits. Because additive is a slow process, the ability to machine a part from stock and then add features helps to save time as well as materials. And hybrid manufacturing makes it possible to deposit the same or different material onto an existing part, useful for cladding one material onto another or repairing damaged parts.

But the advantages could be even deeper. In a talk during the most recent Additive Manufacturing Conference, Dr. Hyatt discussed several potential uses for hybrid machining using laser deposition. For instance, if a part is cooling and contracting too quickly, the additive laser can be used to reheat those areas. Another option would be to machine additive features while they’re still hot; according to Dr. Hyatt, machining the metal before it has fully solidified eliminates chatter (though he noted that any chatter could be catastrophic for the meltpool). It could even be possible to deposit material on a workpiece from above, while the same part is being machined from the lower turret.

More research and testing is needed on these strategies, but, currently “‘precision additive manufacturing’ is an oxymoron,” Dr. Hyatt says. Until and unless that changes, AM will continue to be supplemented by machining, turning and grinding operations.

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