Effect of Workpiece Flatness and Surface Finish on the Holding Force of a Magnetic Chuck

Magnetic chucks are commonly used for workholding in precision grinding and turning of ferromagnetic materials. The workholding force produced by the chuck is strongly influenced by the texture and form of the workpiece surface in contact with the chuck surface. This paper presents the results of an experimental investigation into the effects of workpiece surface flatness, finish, and texture on the normal and frictional workholding forces produced by a radial 4-pole electromagnetic chuck. Ring shaped case-hardened steel specimens were used in the experiments. The results show that the normal holding force decreases with increasing flatness deviation. The effect of surface roughness on the normal holding force was found to be small compared to the effect of flatness but significantly impacts the tangential holding force. The workpiece surface texture was also found to have an effect on the workholding forces.