(^174) PC Hardware: A Beginner’s Guide
the HDA case. The spindle disk motor is designed to prevent oil or dust from contaminating
the components to the sealed dust-free environment inside the HDA. At the spindle and
spindle motor’s high rotation rates, the lubricating oil in spindle and motor assembly can
be turned into a mist. Special seals are placed in the spindle motor to prevent oil leaks.
On the bottom of most hard disk drives is thespindlegroundstrap,which is a small flat
and angled piece of copper with a piece of carbon or graphite (some older drives may
haveaTeflonpad)thatismountedsothatitisincontactwiththespindle.The purpose of
the ground stra pis to discharge any static electricity created as the s pindle turns
preventing it from being discharged inside the HDA and damaging the disk drive or
corrupting stored data.
Storage Media
Although not listed as a major component in the list at the beginning of this section, the
material on which data is actually stored is nonetheless a very important part of the disk
drive. Thestorage media, or the magnetic material that holds data on the platters, is a very
thin layer of magnetic substance in which electromagnetic data is stored.
Data is stored on a hard or floppy disk using electromagnetic principles. A magnetic field
is generated from a magnetic core wrapped or surrounded by an electrical wire through
which an electrical current is passed to control the polarity of a magnetic field. As this
magnetic field is passed over the disk, it influences the magnetic polarity of a certain area of
the recording media. Reversing the direction of the flow of the electrical current reverses
the polarityofthemagneticfield,whichreversestheinfluenceithasontherecordingmedia.Figure 9-3. Views of a spindle motor. Image used with permission from Samsung
Electro-Mechanics of Korea