Many thanks for the replies. That is a LOT to think about and I'll certainly experiment with speeds and feeds etc. Thinking about it... it did make more noise when feeding slower- I was too scared to go faster
It was also making more noise when I was machining towards the chuck than away from it (the tool was at 45 deg to the diameter).
Much food for thought, thanks for the tips!
I was using these little things- it says carbide on the box (apologies for the poor pics, my camera is on the way out I think)