Hardware Insights Forum

Although fluid-dynamic bearings have long since replaced ball bearings in HDD spindle motors, ball bearings persist for supporting the head assembly. While fluid-dynamic bearings have great advantages for spindle motors (more shock resistance, doesn't get noisier or develop higher NRRO with age or thermal cycling), they have not eclipsed ball bearings for head assemblies, for two reasons:

• The advantages of FDB over BB are not as pronounced for head assemblies (spindle rotation being continuous, but seeking only intermittent). You can get an easy 10 billion spindle rotations, but it would take a long time to reach 1 billion seeks, in desktop use.
• FDB has a critical drawback for the head assembly - it can only sustain continual rotation in one direction.

I hypothesised a workaround for the second one, by supporting the head assembly from a spinning motor. Whether it's practical, I really don't know.

It's possible that thermal cycling may produce more wear on ball bearings than seeking itself, though I'm not certain.

The question here is, will they ever use different bearings for head assemblies???

I went with option 3. It is possible, I'm sure. However. I think SSDs will probably replace HDDs before it happens.