Crofer 22 machining

[dapoopta]

Hello all,

I am new to this forum, so I would like to say hello first. There we go...

Anyway. I am trying to machine a small .5" piece of crofer by putting pockets into it. I am trying to figure out good feeds and speeds, but can't find any good ones. I am using a Haas TM-1. The end mill I am using is a 1/32" 2-Flute Carbide endmill. I started with 1in/min and 6000rpm spindel, removing .005" per pass, but it only lasted about one pass over the material, then the tip of the tool broke. I am currently not using any coolant, but I could hook it up if it is totally necessary. Thanks for your help guys!!!

[mpstech]

I'm really no machinist, but I would say you need to reduce your depth to
about .0005 instead of .005. Since your trying to machine hardened stainless, you may want to to even go less maybe .0002 depth per pass.
A much higher 15,000+ rpm or higher spindle is also recommended. Try a spindle speeder or add on a high speed spindle somewhere. Mount a die grinder or dremel and try again with a much shallower depth. You may also be able to increase the feed rate then. Your lacking spindle speed !

** ADDED **
HRB hardess is 70-90 on this material
Maybe someone can give you speeds, feeds, and tooling to machine something at this hardness level.

http://www.thyssenkrupp-vdm-fareast....fer22apu_e.pdf

[dapoopta]

My max spindel speed is 6000rpm. I would also say remove less material per pass, but this process is already taking 5 1/2 hours... with the tool breaking. I am trying to figure out how to optimize it. Can someone explain what benefits coolant would bring, since I have never worked with it.

[dylskee]

Coolant will definitely help, even if you bought a mister that would also be a great help. The coolant will keep the work pc from hardening even more from the heat generated from the tool. Here is a link to some of the units we use on our older bridgeports. http://www1.mscdirect.com/CGI/GSDRVS...00000031175827

You could also use some WD40 from a spray bottle, I've done that before with success. I would probably go with a 4 flute endmill too.

[dapoopta]

Thanks for the tips dylskee. I have a few more 2 flutes to try out. Do you guys think spinning at 6000rpm and moving at 1in/min is a good idea? What would the optimum feeds and speeds be for this job? Thanks again.

[dapoopta]

Ended up going to .003" depth and 4 flute 1/32" end mill at a feed of 1in/min