servo track writer (STW)

The servo track writer (STW) or servo writer is used in the manufacture of hard disks for writing servo tracks. These are used by the servomechanics to position the actuator arm with the read/write heads. Servo information is written to the servo tracks at a specific frequency to assist the hard disk head in accurate positioning.

Servo track writers functionally consist of a spindle that gives the read/write heads the exact speed to fly over the hard drive and the correct frequency to write and read data. Furthermore, a servo writer consists of the actuator with its precision positioning system, which ensures that the servo information is written on a circular track. Up to 120 servo information are written on a circular track per revolution.