The importance of the spindle motor contained within a hard disk is often overlooked, with most people only think about the speed at which is rotates the drive platters. Not only is do these need to spin at a constant speed to a high degree of precision, but they must also be quiet, and not lead to the platter being about to move out of alignment, which could result in the destruction of the magnetic recording surface, the read/write heads, or even the platters themselves.
The spindle motor is required to operate continuously at a constant rotational speed, while avoiding any vibration which could result in a resonance, whereby the platters could start to move out of alignment. It is the workhorse, and a failure of the spindle motor will always require professional data recovery, to rebuild the drive, in order to recover the data.
Traditional Ball Bearing Motors
Up until the early 2000’s, almost every hard disk drive spindle motor contained ball bearings. These would support the spindle motor and ensure the platters were centrally located. Ball bearings however have three design limitations for use within hard drives: rotational speed, storage capacity and noise issues.
Ball bearings can only rotate up to a certain speed, before they will begin to overheat, causing problems with the lubricants which will outgas. They also have a limited lifespan, which will result in a limited lifespan.
The storage capacity in the drive was limited by the magnetic density of the recording layer, but increase density saw a requirement for lower read/write head flying distances, as well as higher precision required in platter alignment. However well manufactured ball bearings are, they will usually contain an inherent wobble, which limited the precision of alignment.
With hard drives being widespread in the office and home environment, it was also important to find a solution which would produce less noise.
Fluid Bearing Motors
A fluid bearing, also known as a liquid bearing, is essentially a small quantity of lubricant which is trapped with a high precision machined housing. The use of fluid bearings has addressed the three issues that were apparent with ball bearing motor spindles, leading to higher speeds and magnetic recording density, along with a reduction in noise.
With no mechanical connection between the platters and the motor, vibrations and noises are no longer transmitted between the two, leading to less chance of a resonant vibration occurring. The fluid in the bearing also acts are a damper, helping to reduce the levels of noise.
Fluid Bearings and Data Recovery
Although an impact event is still highly likely to cause a failure of the spindle motor, the extent of the problems have been lessened, as fluid bearings are more shock resistant than ball bearing motor spindles.
It is essential though, that if a spindle motor is damaged, that the drive is not powered up, as it may lead to further failures, such as the read/write heads coming into contact with the hard disk platters. Data recovery from a failed spindle motor requires the drive to be rebuilt before it can be powered up, in order to avoid causing widespread damage to the magnetic recording surfaces.