Hybrid Machine Combines Milling and Additive Manufacturing

Metal parts produced through additive manufacturing almost invariably need machining as a follow-up step. Only the subtractive process can achieve the most narrow tolerances and smoothest finishes. Far from being opposite or competitive processes, additive manufacturing and CNC machining actually go together. They belong in the same machine.

At least, that is the thinking of Sauer Lasertec. This company, known for machines that perform material removal through laser ablation, has been working with DMG Mori USA to develop a hybrid machine tool combining laser metal deposition for additive manufacturing with five-axis CNC milling. Sauer Lasertec is also part of the DMG Mori group. The hybrid machine—operating now as a concept model, but planned for launch next year—will be presented at the Euromold show in December in Frankfurt, Germany.

The 2-kW diode laser head locates in the machine’s spindle with an HSK interface. For the shift to machinining mode, this head swivels to a protected parking area. By using laser deposition to build up the part, while employing milling throughout the process to machine critical features as the part is taking shape, the machine can produce a component through additive manufacturing while also producing it to its completed tolerances within the same cycle. Yet this single-setup processing is not the only benefit of the combination.

“By combining additive manufacturing with milling in one machine, additive technologies are no longer limited to small workpieces,” says Gregory A. Hyatt, senior vice president and CTO of DMG Mori Advanced Solutions Development. “Our focus is to create a solution for larger workpieces found in industries such as aerospace, mold/die and energy.”

Fast deposition rates are key, he says. The laser depostion process works by spraying metallic powder into the laser beam. The company reports that the build rate of up to 3.5 kg per hour is up to 20 times faster than laser sintering, an accepted metal additive manufacturing process. As the material is rapidly added in this way, CNC milling can be employed wherever fine precision is needed.

The machine to be shown at Euromold is based on DMG Mori’s DMU 65 machinining center, which has 650 mm of travel in X and Y. Another promising application of this machine is repair, modification or coating of the relatively large parts that these travels can accommodate. Repair of dies and molds is one example. Another is completing components for the oil and gas sector, in which Inconel is used for corrosion resistance. In this application, the machine could be used to add Inconel coating or Inconel features to a base part made from a different metal.