GrindBall: an advanced micro-grinding tool

Small machine tools and inherent miniaturized components are persistent development topics in scientific research. Miniaturization usually requires not only reproducing existing systems at a smaller scale, but also a complex integration of various functions into one single element. This concept is presented here by means of a miniature spherical grinding module (GrindBall). It combines a specifically developed magnetic bearing with fluid dynamic propulsion, thus enabling novel grinding kinematics and the possibility of integration in small machine tools. In this paper, the requirements of micro-grinding processes are introduced and the manufacture as well as performance of grinding spheres are discussed; the design of the magnetic bearing is presented and its functionality validated in experiments. Finally, results from numerical simulations leading up to the development of the propulsion system as well as its geometric layout are reported.