Hard Disk Drive Hermetic Block
The basis of the hard disk drive construction is the cast metal case protecting magnetic disks and the fine mechanics from the influence of environment. It is almost completely hermetic and protects the hard disk drive from particles of dust, which can damage a sensitive magnetic layer and put the drive out of action if they get into a narrow gap between the head and the disk surface. Besides, the case shields the store from electromagnetic interference. The internal volume of the case is filled by air cleared of dust. Assembling of the hermetic block is carried out indoors, where one cubic meter of air includes less than one hundred particles of dust. There is an aperture in the case closed by the dense filter that provides adjusting internal air pressure to atmospheric pressure. At rotation of disks the stream of air circulating in the hermetic block, which passes through one more filter, is created, being additionally cleared of dust.