New design of a HDD spindle motor using damping material to reduce NRRO

This paper investigates the dynamics and NRRO of a 2.5" HDD by using FEM, modal testing and runout analysis. Most frequency components of NRRO are generated by the defects of ball and rotating race, and they are transmitted to disk through the spindle system. Based on the characterization of NRRO, it proposes the novel design of a spindle motor that can reduce NRRO effectively by inserting a viscoelastic damping material in a transmission path of NRRO, i.e., where the strain energy is highly concentrated.