Tool type and macrostructure for magnetic abrasive finishing of flat surfaces on CNC machine tools

Magnetic abrasive finishing (MAF) can be used on CNC machine tools as a final machining step to finish workpieces after the milling process. This paper presents a new tool system for the magnetic abrasive finishing of flat surfaces on traditional CNC machine tools using permanent magnets and a paramagnetic adapter without magnetizing the spindle. Five MAF-tool types with variated dimensions, quantity and arrangement of the permanent magnets were developed and tested for machining ferromagnetic materials at different feed rate and equivalent cutting speed. The magnetic flux density was measured for all MAF-tool types with a Hall sensor and the distribution is presented graphically. The benefits of a novel top cover structure for MAF-tools are presented and 20 types of structures were tested as well as divided into three groups. Optimal top cover structures lead to a significant increase in the process capability and a surface roughness reduction for MAF of flat surfaces of ferromagnetic workpieces. Furthermore, the significant influence of the top cover material on the process capability was discovered and a total of seven metal and plastic materials were tested, which were milled from solid material or additively manufactured.