Milling S7 Tool Steel

[GSSTUART]

I am shapinging some air hammer anvils for a friend and having trouble finding recommended feeds and speeds for S7 tool steel. The material I have is supposedly annealed but when I take a facing cut of about an inch width with a 2 in. 3 flute carbide insert cutter (2000 rpm) at 0.050" doc and 8 ipm the cutter is throwing a lot of red hot chips and sure seems to be working hard. I tried slowing way down on the spindle speed (400 rpm) and 5 ipm as recommended in "ME Consultant" but it felt like I was beating everything up. I have a 2 hp spindle. Any suggestions?

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[Geof]

2" diameter at 2000 rpm is more than 1000sfm and 8ipm gives a chipload of 0.0013 per insert in the cutter.

I think your speed is way high and your feed way low.

Did you change the inserts before slowing the speed down? I think you probably rubbed the edge off them with such a high speed and small feed.

You are limited in power so probably you cannot do several hundred sfm with a decent chipload such as 0.01 per tooth so I think you will have to poke along as you are maybe at an even slower feed. It probably is going to make a lot of noise because you are machining tough stuff.

[John Welden]

If you only have 2hp you're probably using a pretty wimpy machine. Smaller cutter, smaller cuts. You've got to do what you need to do to get it to cut and not rub while not beating the crap out of everything. That S7 is tough and doesn't want to go away easily.

[Andre' B]

First off if that 2" 3 insert cutter uses triangular inserts, take it to the nearest lake and throw it as far as you can off the end of the dock.
Then order a face mill with some good positive rake angle.

Second on harder tough steels and a 2hp spindle you will likly remove metal faster with a 4 flute 3/8 coated end mill then you will with a facemill, use one with around 0.030 corner rad.