Residual stresses and workpiece deformation due to polishing and plating of computer hard disk substrates

摘要

Residual stress distributions due to plating and polishing were determined for nickel-phosphorus plated aluminum alloy disks. Knowledge of these stresses provides insight into the material deformation and removal processes, information as to theeffects of processing conditions on residual stress magnitude and can also serve as a basis for development of models of material deformation and removal in polishing. Measured disk shape data was fitted to an analytical solution for plate displacementdue to bending moments, and residual stresses were calculated. Plating and polishing residual stresses were separated. Polishing residual stress is compressive indicating differential plastic deformation between the surface and interior regions of theworkpiece. Residual stresses produced in polishing operations in which process motions were constrained so that polishing was unidirectional were measured. The results show large differences between amounts of deformation in the polishing direction andthe direction perpendicular to it.