Abstract: A disc drive includes a base and a disc rotatably attached to the base. The disc drive also includes an actuator assembly rotatably attached to said base and a device for moving the actuator assembly. A cover is attached to the base. The combination of the cover and base form a disc enclosure for enclosing the disc the actuator assembly and the device for moving the actuator assembly. An inertia ring is attached to the disc enclosure for increasing the moment of inertia of the base and cover. The inertia ring may be attached to the cover or to the base. The inertia ring may be formed of a material which is more dense than the cover or more dense than the base. The inertia ring may also be formed integral with the base or the cover. The inertia ring may also be formed such that the material is positioned near the periphery of the base and attached cover. A damped interface between the inertia ring and the base or cover may further reduce movement of the base with respect to the actuator.

Abstract: Apparatus and method for cooling the actuator coil with a suitable heat sink structure. The heat sink thermally couples the coil to one or more of the head-carrying arms, which are positioned close enough to the disc stack that rotation of the stack cools them. In one embodiment, a gap is formed between the coil and a thermal conduit, and the gap is made wide enough to allow a majority of the gap to be filed with a solid dielectric. Another embodiment is a method for controlling the minimum gap thickness. In yet another embodiment, a rotary actuator includes a heat conduit with a concave surface for bonding to the coil, increasing rigidity and thermal conduction.