Can Measuring your Spindle's Electrical Resistance Indicate the Lubrication Level?

[rgsparber]

The short answer: I don't know.

However, I just completed a survey that implies that you can characterize your machine and know when your bearings are dry using an ohmmeter.

If you are interested, please, click here


Your comments are welcome. All of us are smarter than any one of us.


Thanks,

Rick

[nova_robotics]

That's some good work there Rick. One tiny note, I done goofed on the data I gave you. I gave two values for resistance, for example 0.09 and 1.2, were for stationary and rotated respectively. The low value was for a stationary spindle, the high value was for the rotated spindle. I just got it in my head that rotated would always produce a lubricant film and be higher resistance, but I forgot to actually write that. Sorry about that.

[rgsparber]

That's some good work there Rick. One tiny note, I done goofed on the data I gave you. I gave two values for resistance, for example 0.09 and 1.2, were for stationary and rotated respectively. The low value was for a stationary spindle, the high value was for the rotated spindle. I just got it in my head that rotated would always produce a lubricant film and be higher resistance, but I forgot to actually write that. Sorry about that.

Thanks for the correction. I see other entries where I misinterpreted the same way. All corrected now.

I am reminded of a comment made by one of the designers of Auxiliary Power Units that are used in jets. He said they use magnetic bearings so when running at the full 50,000 RPMs, the spindle does not touch the housing. However, when stopped, the spindle rests on the housing. I asked how you get from stopped to full speed without tearing things up. He just smiled and said that is where the magic occurs.

[nova_robotics]

I am reminded of a comment made by one of the designers of Auxiliary Power Units that are used in jets. He said they use magnetic bearings so when running at the full 50,000 RPMs, the spindle does not touch the housing. However, when stopped, the spindle rests on the housing. I asked how you get from stopped to full speed without tearing things up. He just smiled and said that is where the magic occurs.

Hard drives have all switched to air bearings. The spindle floats on an air bearing, and the heads float above the surface of the magnetic disc because the boundary layer effect causes the heads to "fly" just off the surface, which is also essentially an air bearing. What happens when the hard drive is spinning up or spinning down? More magic I guess.

[bob47907]

As far as the read/write heads go, each platter has a ‘landing zone’ where no data is stored. Often, the zone is coated with a low-friction material to protect the head.

[nova_robotics]

As far as the read/write heads go, each platter has a ‘landing zone’ where no data is stored. Often, the zone is coated with a low-friction material to protect the head.

Yup. But what about the spindle bearing?