The hard disk platters are accessed for read and write operations using the read/write heads mounted on the top and bottom surfaces of each platter. Obviously, the read/write heads don’t just float in space; they must be held in an exact position relative to the surfaces they are reading, and furthermore, they must be moved from track to track to allow access to the entire surface of the disk. The heads are mounted onto a structure that facilitates this process. Often called the head assembly or actuator assembly (or even the head-actuator assembly), it is comprised of several different parts.
Hard Disk Drive Magnets
50% of the world’s neodymium magnets are currently used in computer hard disk drives (HDD) with each HDD typically containing two magnets. The magnets are used in the actuator – a device which moves the actuator arm on the tip of which is the head which reads and writes data to/from the ultra-delicate platters. Driving the arm using magnets means that mechanical wear and tear is not an issue – unlike old-fashioned stepper motor powered hard drives.