Abstract: Embodiments include a disk drive having a drive motor assembly including at least one component selected from the group consisting of a rotatable hub, disk spacer, disk clamp, backiron, lower bearing bushing, and lower mounting flange. At least one of the components comprises a low sulfur outgassing free machining stainless steel material. The low sulfur outgassing free machining stainless steel material may include a free machining stainless steel that outgases sulfur at a rate insufficient to cause visually observable sulfide corrosion when tested by placing a copper strip into contact with the free machining stainless steel in an environment having a temperature of 50° C. and 90% relative humidity for a 7 day test period and then observing the copper strip.

Abstract: A ring shaped-disk clamp for clamping a disk stack to a spindle motor. The ring-shaped disk clamp is referred to as a shrink-fit disk clamp and must be expanded by heating prior to being inserted onto the hub of a spindle motor. Once inserted onto the hub of the spindle motor, an external axial load is applied to the disk clamp. As the disk clamp cools while applying the external load, the clamp contracts and provides a gripping force on the hub of the spindle motor. Subsequently, the external load is removed. The ring-shaped disk clamp includes a top surface, a bottom surface for contacting the disk stack, and an inner peripheral surface for contacting the hub. The inner peripheral surface contacts the hub at a hub contact area that is optimized to provide a localized gripping force on the hub. By optimizing the location of the hub contact area, the disk clamp can provide a relatively high gripping force with a low coefficient of friction between the disk clamp and the hub.