Suggestions on milling 304 SS plate

[liftoff]

I need to mill a 3/8" thick 304 plate into a particular 2D profile. I'm wondering about the best way to do this. The time to mill the plate is unimportant, but I'd like to preserve tool life if possible. The approximate shape is a ring, 10" OD and 8" ID. I have use of a Haas TM-2 mill.

The approach I'm considering is to lead in from outside the stock (or, for the inner profile, from a pre-drilled hole), and cut around the profile at full depth. I bought a cobalt 1/2" dia. coarse profile roughing end mill for this purpose. Doing some reading indicates that about 0.0015" ipt, maybe 50-80 sfm is right; I'll flood-cool. I would then run a finish profile with a finishing mill, taking off maybe 0.010".

My main concern is that this profile is perhaps a bit too much to bit off in one pass. After all, this profile is really a slot at nearly 1*D. Would it make sense to run the same profile three times (say), taking off 1/8" in depth at each pass? Doing it this way, however, it seems to me that the tool will wear out faster since I'll only be using the bottom 1/8" of the tool for real cutting.

Any suggestions on my proposed method, or feeds/speeds would be appreciated.

[Shane123]

i see chatter in your future! first, get a piece of wood or uhmw or something you can mount under it, since you are cutting thru. you might even consider drilling the center hole in a first op, then using that to bolt the center down to the table thru the under-layment, and then i would ramp down (.05-.1 per full pass) your id size and skip all that hogging. or better yet, ramp down and leave .01 on the wall, and .02 onion skin on the bottom from ramping, and then step over your .01, plunge down your last .02 to break thru, and then finish profile the id.

as for tool wear, its 304 plate. that stuff is nasty on cutters, and corners. if you could do this work with a radius corner endmill, you should be better off for tool life.

i would use a coated carbide endmill, like TaIn coated with variable helix, but only because i have found ways to abuse them and keep them living feed 30ipm, rpm of 5500, flood coolant of course....

[djr76]

you consider getting them laser, waterjet, or plasma cut? call around for pricing, might be cheaper and alot less hassle, then what you plan on doing.

[Shane123]

yeah, djr has a good point. I would consider that my first option.