Laser printing of metals has proven itself as a viable manufacturing process. No longer just for “impossible to machine” or waifish parts where material characteristics were the design feature needed rather that microstructural strength, 3D now delivers on a dime. It is no surprise then, that manufacturers with million-dollar multi-function machines, now want a 3D print head to fill one of the many open spots in their on board tool-changers.
Hybrid machines that combine different operations are nothing new, at least for standard subtractive machining. They are disproportionately hard to program (and expensive) and so they don’t really speed up manufacturing all that much. What they do provide is accuracy. An internal fixation screw used to rebuild spines can not be turned on a lathe, and then transferred to a mill to broach a hex-head, if the tolerances on the flats are just one or two microns. That’s because no operator, human or robotic, can reposition a part across machines with that precision. Even the same part held in two different set-ups on the same machine would be difficult because the machine itself is probably expanding and contracting by much more than that tolerance over the timescales of such an operation. Some machines even have fluid pumped through the hollow threaded shaft of the drive that moves the axes so that it remains at constant temperature.
On the other hand, 3D additive laser printers will never have this kind of accuracy and will invariably need to have secondary subtractive machining done to them to get the final part. The solution to these issues is a machine like the DMG Mori hybrid mill. Recently demoed at the Euromold show in Germany, this machine can bring the most difficult of designs to life right before your very eyes. It is the result of a collaboration between Mori and Sauer Lasertec to combine 5-axis mill capability with 2 kilowatts of diode laser fusion power.
We mentioned tool interfaces recently when discussing spindle specs for exoskeleton arms and moon rovers. This new machine comes with the fairly new, but now proven HSK interface. Usually made of H13 alloy steel, this tool-holder might one day even be made by the very machine that uses it, provided the heat and temper of the laser-crafted steel could be properly controlled — and a few of the tools in the pallet are grinding wheels. Part of the challenge in building a hybrid machine is satisfying the secondary needs of the laser head. An HSK spindle already provides hydraulic power for the clamping, which might additionally be tapped for laser positioning operations. The spindle is also water cooled and the same source can provide laser head cooling.
Finally, any good machining head needs to have “through spindle” coolant which blasts through the center of the spindle — actually the rotor of an integral motor spindle. This feed itself is no slouch, usually 1000 psi at fairly decent flow, and so capable of doing some additional sidework. This same line can be co-opted by the laser head to source air to provide the “assist” needed to blow out the kerf (if for example also doing laser cutting). So it is not impossible to build such a machine, and indeed it appears to have been done successfully. We might now look forward to marvellous things; the at-home replicator, capable of producing just about anything, creeps ever closer to reality.
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