[zstangkrewson]

Im very new to working steel, iim used to milling polypro plastic on router table cnc machines.

boss just purchased a V4 haas, sweet machine, coolant flood chip evac etc... we bought a drill mill to drill out the center of some 4in round 1018 steel, now he want us to take .21in off the surface of the pieces. have purchased some multiple flute carbon tip (replaceable tips) end mills, but im new to this material, and what im having a hard time telling him is this machine is high speed milling, i cant grasp how fast this machine can run, until i see it myself... so, what i want to use a 1/2' 4-5 flute carbide tipped endmill to surface .21inches of the face of a round 4 in 1018 steel. if i go by the settings bobcad has pre-installed in its software, its going to take forever.... what speeds and feeds would you gents use/recomend? i get alot of ipm data from other sources and have yet to figure out how to convert ipm to sfm. thank you in advance.

[ghyman]

Assuming you are using inch dimensions for everything, then here are a few things to get you started:

RPM is (obviously) Revolutions per Minute.

Most tools will have a 'sweet spot' for speed; it is generally indicated in SFM ==>> Surface Feet per Minute. For carbide inserts, this number should be readily available from the tool manufacturer.
This is good to know, because the SFM for a certain grade of tool will be the same regardless of diameter (generally speaking, that is!)
So it is always good to know how to get from SFM and Diameter to RPM.
This is the most accurate way: RPM = SFM / (Dia * Pi / 12)

Next, is the other half of your question... IPM (Inches Per Minute)
This will be a function of the RPM as well as the recommended chip load of the tool you are using.
Chipload is the amount of material per flute that the tool can comfortably remove. Again, the manufacturer should be able to supply this information.
IPM is: Chipload X # flutes X RPM

So...

Your 1/2" endmill would look like this:
(Assuming a SFM of 150, and a chipload of .002" and 4 flutes)

RPM = 150 / (.500 * 3.14159 / 12)
RPM = 150 / (.1309)
RPM = 1146

IPM = .002 * 4 * 1146
IPM = 9.17


I would check with your tool supplier for some more specific numbers, but the ones I used should be good enough (maybe a little conservative.)
Please note, these numbers assume a short, stubby, rigid tool (<5:1 diameter to stickout) and a rigid setup for the part as well.

There are a lot of good resources online for speeds / feeds, but I hate to give one in particular - just search online for "machinability" and the alloy you are cutting, and you should find a lot of good starting points.

I say "starting points" because every setup is different, and your specific tool / machine / material may not perform exactly the same as the people who put out the speed and feed information.

[dmsgdt112]

Off the top of my head, I run a .375 VM at 5700rpm and 35ipm at full depth in hot roll steel. I can cut 50 flanges before the tool dulls enough to affect my finishing pass. I can usually get 100 flanges done before the bit quits. These flanges are triangular, around 5" x 5" with a 3" center hole.