Overmolding of actuator E-block by thixotropic or semisolid forging

An actuator E-block for a rotary data storage device has a number of solid flat arms and flat coil yokes. The arms and yokes are formed from a metal, metal-reinforced metal matrix composites (MMC), ceramic-reinforced MMCs, glasses, ceramics or ceramic composites having a low density metal matrix surrounding reinforcing particles of low density and high specific stiffness. The arms and yokes may be formed as inserts by inexpensive processes such as stamping, blanking or laser scribing. The arm and yoke inserts are placed in a mold and then overmolded with a metal or metal matrix composite E-block body using a thixotropic or semisolid forming process. After molding, these materials and processes form a cost effective, lightweight E-block with a near net shape and enhanced damping and stiffness.