The Fused Filament Fabrication Technology (FFF) was originally developed for the additive manufacturing of complex polymer parts. Using a thermoplastic filament with high metal powder loading (up to 60 vol%), the technology can also be utilized to print metallic green parts that can be debound and sintered to nearly full density. Printing studies at Fraunhofer IFAM gave promising results with regard to printing defects and green density. However, the surface quality, freedom of geometry as well as dimensional accuracy are limited according to the method and the used nozzle size. To overcome these limitations, a combination of the FFF process and Computer Numerical Control (CNC) milling was investigated. CNC milling can be used for green parts as well as for brown or sintered parts to improve the above mentioned limitations. Besides CNC machinability tests in the green and brown state, the investigations included surface comparisons in the as printed and CNC milled state as well as the discussion of dimensional accuracy in this context.
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