[cncfun1]

Hi All, I am not sure if this topic has been covered already, but i have a issue with a cnc milling machine we are building. It uses a JianKen Spindle JGL-80/1.5R24, which has a max rpm of 24000 and ISO20 taper

We are very happy with the performance of the spindle and are able to run up-to 3Cubic Inch MRR. typical cuts are
DOC = 5mm
WOC=3.2
feed rate is 3000mm/min

We are mostly cutting aluminium T6061 and using 9 and 10mm cutters, at between 19000 and 22000 rpm.
As I said the spindle performs as expected, However we are having an issue with fretting in the spindle taper.
We can see signs of fretting after only 4-5 hours of use at these typical loads, has anybody else experience issues like this?

I have attached images of the tool-holder fretting but similar marks can be seen on the spindle taper. Also this has happened on a few spindles so its not a one off.

any feedback would be greatly appreciated.