Tolerance ring with low consistent installation force profile

A disc drive, comprising:

• a basedeck;
• a spindle motor supported on the basedeck;
• a disc supported on the spindle motor for rotation about a disc axis;
• a moveable actuator assembly which supports a head adjacent the disc, the actuator assembly having a central aperture with an inner surface defining an actuator axis;
• a stationary shaft supported on the basedeck having an outer surface and which defines an actuator axis nominally parallel to the disc axis;
• and
• a tolerance ring compressingly disposed between the inner and outer surfaces to mount the actuator assembly for rotation about the shaft, comprising:
• a substantially cylindrical base portion extending an axial length along the actuator axis and a radial distance from the actuator axis;
• and
• a plurality of spaced apart raised portions radially extending from the base portion each consisting of an arcuate contact surface with a substantially elliptical cross-section in a direction parallel to the axial length and a pair of arcuate transition portions between the contact surface and the base portion each having a continually radiused cross-section in a direction parallel to the axial length so that, for each raised portion, a selected one of the elliptical cross-sections and the pair of radiused cross-sections is convex with respect to the actuator axis and the remaining one of the elliptical cross-sections and the pair of radiused cross-sections is concave with respect to the actuator axis wherein the tolerance ring provides a substantially constant and consistent insertion profile along an axial length of the actuator axis.