Spindle funny noise

I have installed a 2.2 kW water cooled spindle on my machine and initially I did run it for few hours at low speed (5000 RPM) with no load.
Then I gradually increased the speed up to 24000 RPM.

I have used the spindle for some test cut on wood, nothing serious, less than one hour work and I noted a funny sound that I have recorded in this video https://www.youtube.com/watch?v=FzVwleJvOBo. Looks like I have a bunch of frogs in the spindle!

In the video the initial speed is 5000 Rpm than I increase it to 10000 RPM and the noise starts. It makes the intermittent frog noise between 8000 Rpm and 24000 RPM with and without load.

I forgot to say that there are no vibrations and the spindle is turning freely by hand.

Do you think the spindle is faulty?

Is the noise definitely coming from the spindle? Really odd sound ...

Are you sure that there is not a birds nest in there:cower: Or is the pump blowing air bubbles through it ?

Quote:

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Originally Posted by Millone

Do you think the spindle is faulty?

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I think you have air bubbles in your cooling system. Is there a good flow? I'd start checking that, or maybe the pump.

I'm going with Clive on this one!

Sounds like something in the water lines to me, air bubbles, drain the spindle down and spin it back up empty and see if the noise has gone, then investigate what if anything has got into or is going on in the cooling lines built into the spindle.

Don't worry you can run it dry for these intermittent tests, obviously dont leave it running dry over night or cutting anything.

Couple of long shots.

Might be one of the bearings in the spindle is not seated properly and is skipping around. Loctite might sort it but does mean spindle disassembly.

Or electrical connection to spindle is arcing - does this have a plug on the top of the spindle. Take it off and check for arcing / black on the pins. Check the wires are tight into the VFD.

https://youtu.be/WAHKldA4cKg

If I leave it several months without use my little CNC mill spindle motor will make a similar noise until it warms up if I run it above 5Krpm, it seems to be electro-mechanical noise generated when the motor slips a little too much and the VFD tries to sort it out.