Hi, I need some advice about feed rates as I dont usually use such small cutters.

I'm cutting open ended slots to a depth of 2.5mm in 316 stainless with a 4mm 2 flute carbide cutter with flood coolant at a depth of 0.6mm per pass.

Using the speeds and feeds wizard as maths was never my best subject, It calculates for hard steel that I should use the highest spindle speed my machine offers
which is 1750 rpm for carbide.

What I'm not sure on is the chip load per tooth which I set at 0.02mm. This gives out a feed rate of approx 71mm/min.

I managed to get 5 of these slots done but could hear a bit of complaining and checked the cutter, the edges were rounded off.

I'm now down to my last 4mm cutter so I'm asking you, "Cap in hand" what might be my problem, Usually dulling of the ends means too much rpm but I've read that the big guys use carbide at thousands of rpm so my logic says perhaps I should reduce the feed rate.

My only worry is that if I reduce the feedrate work hardening of the material may take place.


G code attached so you may be able to suggest a better way of doing things

Many thanks
John

I think I would be a bit slower on the feedrate than that, would probably be about 1900 to 2000rpm and a feed about 50mm/min and plenty flood coolant. All depends on your setup and machine however as rigidity is needed for carbide. I often use and get better results from using HSS Co8 cutters, slightly slower on feed and RPM  but works well and they seem to last

Hood

Hi Hood, Thanks for your advice, Sometimes you can forget the obvious and after I changed the setup to make the material more rigid I have completed the items and the cutter is still as new.


Many thanks.

John

Glad it helped
Hood