The internal structure of a hard drive consists of a fixed panel, control circuit board, heads, platters, spindle, motor, interface, and other attachments. Among these components, the head-disk assembly is at the core, encapsulated within the hard drive's contamination chamber. This assembly includes floating head components, head actuator mechanisms, platters, spindle drive units, and front-end read/write control circuits. Once the hard drive's cover is removed, its internal structure becomes clearly visible.
1. **Head Assembly**: This is one of the most precise parts of the hard drive, consisting of read/write heads, actuating arms, and a rotating shaft. The heads are a crucial and critical aspect of hard drive technology, actually comprising multiple heads integrated through advanced processes. They use a non-contact head-disk architecture, moving over the rapidly spinning disk surface with a gap of only 0.1 to 0.3 micrometers, enabling excellent data transfer rates. In modern drives spinning at 7200 RPM, the flying height is typically less than 0.3 micrometers, which facilitates reading high signal-to-noise ratio signals and ensures reliable data transfer rates.
2. **Head Actuator Mechanism**: Track seeking in a hard drive is achieved by moving the heads, which requires this mechanism for driving. The head actuator mechanism comprises an electromagnetic coil motor, a head carriage, and anti-vibration devices. A high-precision, lightweight head actuator can accurately drive and position the heads, achieving precise track positioning as specified by system commands in a very short time.
3. **Disk Platters**: Disk platters are the carriers of data storage in a hard drive. Modern hard drive platters are mostly made from metallic thin-film materials, which offer higher storage density, residual magnetization, and coercivity compared to the discontinuous granular carriers used in floppy disks. Additionally, IBM uses a material known as "glass platters," which provide better stability during operation compared to regular platters. Hard drive platters are extremely flat, almost mirror-like.
4. **Spindle Assembly**: The spindle assembly includes components like bearings and drive motors. As hard drive capacity expands and speeds increase, spindle motor speeds are also rising. Some manufacturers are adopting liquid bearing motor technology (FDB) from precision mechanical industries. Using FDB motors not only significantly reduces operational noise but also enhances the stability of the hard drive.
5. **Front-end Control Circuit**: The front-end control circuit manages head-induced signals, spindle motor speed adjustment, head driving, and servo positioning. Due to the faint signals read by the heads, sealing the amplification circuit within the chamber reduces external signal interference and improves the accuracy of operational commands.
Original article from Anhui Data Recovery Center: http://www.cndr.cn/hydt/12916.html