301SS milling help needed

[LockTech]

im fairly new too cnc and milling. have been at it for a year or so now.

been milling a notch in the end of 301ss this strip with dim of .125x.022x3.5 inches. i have 10 laying side by side so as to make many the same, and do this repeatively. the notch in the end that im milling out is ranges from about half to almost all of the hieght. i have an mini X2 xyz cnc added and belt drive added with flood coolant running Mach3.

i have used large .5 mills and small .125 mills. and if i go at a feed rate of 1 with 4000rpm it starts to smoke bad seems i get the best results with super slow speeds like .1 to .3 feed rates. but this seems opposite of all that i have read from other posts. and i have always had issues with tool life.

anyone have any comments or things i can try to improve feed rate and or tool life? or questions?

[davereagan]

I'm not sure what is different between 301 and 304, but for a 1/2" endmill, 4000 rpm would be screaming even in mild steel. I would run a 1/2" endmill at more like 1500 in 304. Feed would be .001-.003" per tooth, depending on depth, etc. Of course, the speed for the .125" endmill would be four times higher, with a lot lower feeds.

Dave

[The Blight]

I would even go slower. Between 800 and 1000.

[LockTech]

So, if I am understanding this correctly, the approx speed for a 1/2" em is around 1000rpm's. And the feed rate is suppose to be about .002" per tooth on the em. The em has 4, so thats a feed rate of .008 ipm? Hole crap that sounds like some slow cutting. If this is the case I think I need to redesign my jig to hold more pieces.

Btw, the most amount of material being taken out varies between .100 X .100 to .45 X .100. Does that make sense?

[Alex_Cole]

Lets see if this helps with understanding the feed rates that have been recommended.


They recommended 800 to 1000 rpm. now your cutter is a 4 flute. That is 4 teeth.

They gave you a feed rate of .001 to .003 feed per tooth.

So lets work with 1000 rpm. Now being that we have a 4 flute endmill we take 1000 x 4 = 4000. now take 4000 x .001 and we get 4 Inches per min feed rate.

If you up your chipload to .002 feed per tooth then you would get 8 inches per min feedrate. so you are going slow but not as slow as you were thinking.

FPT mean that the feed rate would move the tool into the material at a rate that will have each flute(tooth) of the tool would enage by an ammount. EG .001


Hope this helps.

AC

[The Blight]

I have never tried to cut steel on my X2, and so I can't say how it holds up. It's not a big machine, so light cuts is the way to go. You will probably have to end up with doing some testing with speeds and feeds to see whats best.

[LockTech]

That was very informative Alex, thx for that explanation

[bilinghm]

300 series stainless is not fun to machine in any fashion. It is subject to work hardening, meaning that as it is cut, drilled, milled, it spot hardens where the tool contacts it. I have had fits trying to band saw, drill and tap 301. 400 series SS is MUCH better stuff. If possible, switch to a machinable grade before you ruin any tooling.

Bill

[LockTech]

thank you all.

the suggestions made above have made a world of difference. now we will see how tool life holds up....