I have recently started using uncoated carbide inserts and was wondering if there is a rule of thumb on how fast to run them and how hard to feed them over HSS. I was machining a piece of 3" gray iron that would eat even a 10% cobalt bit. I switched over to a C2 uncoated carbide and running in backgear at 180 rpm and a depth of .003 with a feed of .003 it machined like a dream with a very nice finish. In HSS this would equate to around 133rpm using 4C/D where C= cut speed of material and D= Diameter.
I then had to bore the piece out and used a Carboloy 883 brazed 1/4" bit in the boring bar using the same speeds feeds and depths of cut and again it cut very well with no chatter.
So is it fair to assume that when using uncoated carbide that you can increase your speed by 30-50 percent over HSS speeds? I tried to check the Kennametal, Valenite, and Carboloy websited and didn't have any luck finding recommended feeds and speeds for uncoated carbide. I also checked
Thanks for any help. -Steve