I have been attempting to turn down the diameter of some small ceramic magnets. I have been using my regular carbide inserts and have not been having much luck. I am flooding the magnet with water, and my lathe is running at its highest rpms. I am only taking off about 1 to 2 thousands at a time and turning my carriage very very slowly. I have successfully managed to turn down 2 magnets so far, but have failed at about 8. Basically, the magnets just crumble if I accidentally take off to much, or twitch with my hand etc....
Is there a specific insert designed for turning ceramic, or are there any special techniques that I haven't mentioned? Is there a recommended insert radius for ceramic?
On my cnc mill, I designed a simple jig to securely hold the magnet. Using a diamond coated 3/16" 4 flute end mill spinning at about 8000rpm with coolant, I am able to machine down the thickness with no problems. I then use a ceramic 1/4" drill bit to drill a hole down the center, again with no problems. But when it comes to turning down the diameter I just can't do it with the tools I have.
Thanks for any info. I am hoping to succeed in this final machining operation.