Characterization and optimization of the dynamic tool path of a highly dynamic micro milling machine
As the manufacturing of components in the field of life science, consumer electronics and micro-electro-mechanical systems (MEMS) demands in many cases the machining by micro milling with cutting tools down to 100 micrometres diameter, highly dynamic machine tools are needed to machine the more and more complex freeform surfaces at optimal process parameters. The paper describes the development of a highly dynamic milling machine which is equipped with linear direct drives in all axes with integrated impulse decoupling units to allow high dynamics and especially high jerks at low impact on the machine structure. To provide the same dynamics of 1.5 g in all three axes the z-axis is mounted separately on the tool side. Passive magnetic actors are integrated in the z-axis as weight compensation to supply the same acceleration in positive and negative z-direction. The impulse decoupled horizontal x-and y-axis are stacked and integrated in a compact and lightweight cross table design. With a total cross table weight of 50 kg, 750 N peak force is needed for the acceleration. To avoid thermal influences the coils and magnet tracks are water cooled. This design provides better process conditions and will speed up the machining time approximately about 20 percent, at less tool wear and better surface qualities. The dimensions of the machine base are 800 mm x 800 mm and the total machine uses about 1 m(exp 2) floor space including periphery. Additional the development of a metrology frame is detailed which can be used to characterize the dynamic tool path of machine tools to optimize its dynamic setup and to increase the work piece precision at minimized machining time.