The Bearing of Hard Disk Drive Spindle Motor
The speed of magnetic disk rotation is about 5400, 7200, 10000 or even 15000 revolutions per minute that mean the necessity of using qualitative bearings. Earlier, the ball bearings with balls made of metal alloys or ceramics used for HDD production. In the modern hard drives, the liquid (hydrodynamic) bearings applied. The special oil is swallowing impact actions used in the bearings of that type instead of balls that aimed at increasing durability of the engine. Liquid bearings have a lower level of noise and almost do not emit heat during the operating time. Spinning parts of the spindle motor in them separated from each other by a membrane of oil which works as an absorber of impact actions and prevents the damage of the bearing working surfaces. The dynamic liquid bearing is capable of extinguishing any vibrations of both internal and external origin quickly while the absence of contact provides a theoretically infinite lifetime of drives with fluid bearings.