The Servo Track Writer (STW) or Servowriter 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
. The servoinformation is written to the servo tracks at a specific frequency
tohelp the hard drive head position itself accurately.
Servo track writers functionally consist of a spindle that gives the read/write heads the exact speed to fly across 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 that ensures that the servo information is written on a circular track. Up to 120 servo information is written on a circular track per revolution.