A spindle motor for use in a disk drive includes a spindle motor base and a motor
shaft. The motor shaft has a central axis. The spindle motor includes a spindle
motor hub rotatably coupled to the spindle motor base, the spindle motor hub including
a central magnetic metal portion disposed adjacent a distal end of the motor shaft.
The spindle motor includes a ball bearing set disposed between and in mechanical
communication with the spindle motor hub and the motor shaft for rotatably coupling
the spindle motor hub to the spindle motor base. The spindle motor includes a shaft
magnetic element attached to the motor shaft at the distal end adjacent the central
magnetic metal portion, the shaft magnetic element being sized and configured to
apply an attractive magnetic force to the central magnetic metal portion in a direction
along the central axis for pre-loading the ball bearing set.
