Extended Study on the Composition of Magnetorheological Fluids for the Post-processing of Micro-milling Tools

Cutting edge preparation is a critical step in the fabrication of micro-milling tools, helping to remove grain chipping and to reduce tool wear. In our previous research, we explored the use of magnetorheological fluids for directed immersed tumbling under magnetic excitation, demonstrating its potential through significant and precise material removal rates and reduced processing times. This study expands on that work by examining how the composition of the abrasive magnetorheological fluid affects surface quality and the long-term performance of the fluid. Various compositions of magnetorheological fluid samples were tested on high-speed steel specimens using a custom-designed test bench, which enables the variation of the magnetic field. The microgeometry of the cutting edges, including the maximum chipping, was recorded before and after processing. Results indicate that compositions yielding larger abrasive particles, combined with high magnetic and abrasive particle volume fractions lead to improvements in surface quality and material removal rate.