German machine tool maker Hermle is integrating additive manufacturing capabilities into a 5-axis machining center, marking a significant leap in the production of complex metal components.
Unlike the metal powder based laser melting process, Hermle’s Generative Metal Powder Application (MPA) manufacturing technology is a thermal spraying process based on low energy kinetic compaction, or micro-forging.
The result marks seven years of development at the company’s R&D center in Ottobrunn, near Munich and a significant level of investment.
The hybrid machine, known as the MPA 40, has a powder application nozzle mounted next to the vertical milling spindle and a heater built into the 4th / 5th axis rotary table.
Once the CAD file is prepared, a high-energy jet of superheated steam propels a metal powder suspended in nitrogen through a Laval nozzle onto a substrate at three times the speed of sound. The impact creates local pressures of 10 GPa and temperatures up to 1000 Â° C. The result is localized superplastic deformation, forging the powder particles together and onto the component surface. The fully dense bonded layer is machined by metal cutting using up to five CNC axes, followed by the deposition of an additional layer. The process is repeated a number of times to produce the required component.
Micro-forging allows up to six different metals to be layered, with a clean or smooth transition between them. Each metal powder requires its own process parameters, which are stored in a knowledge database within the machine control. Currently available materials are hot work steels 1.2344 and 1.2367, stainless steel 1.4404, copper, bronze, titanium and aluminum.
The produced components can measure up to 550mm in diameter, 460mm in depth and weigh up to 600kg with the option of using water soluble filler material to create internal features, such as conformal cooling in plastic injection molds.
While traditional additive manufacturing can achieve a similar result, Hermle’s MPA method takes it one step further with its ability to microforge dissimilar materials, allowing mixed metal solutions like a heat-conducting copper core inside a tool steel exterior.
To coincide, Hermle developed the CAM software MPA-Studio to allow analysis and machining layer by layer to build the geometry of the component. Sequence simulation and quality assurance functions to verify finished components are included.
The company is currently consulting with German customers to identify suitable applications, discuss how the process can be implemented and produce special and dedicated parts.