Ok well I will make some guesses.
If you want to do 20-40 IPM in mild steel .04 deep with (1/8 , 1/16 ,1/4 ,1/32 ,2mm ,4mm, 6mm "rolls dice" 1/8 inch) then you will have to use a spindle running 12000 rpm and higher probably a lot higher. I would recommend good flood cooling, and depending on speed and feed either 2 or 4 flute carbide. Depending on... you are getting into "high speed" machining. The smaller the bits you use the faster they have to turn to keep the chip load reasonable especially at high fees rates like this in steel, especially at that depth. Depending on the size of the bit it might not be at all possible to go that deep in one pass at any ware close to that speed, or at all. If this were wood there would be no problem but this kind of speed in steel is going to take a lot of experimentation and very high rpm.
For example on our metal mill with a 1/8 inch bit cutting 1/8 deep in 2025 alum with mist cooling with the speed cranked all the way up to 5600 rpm I start breaking mill bits at 12 ipm. If it were mild steel I couldn't go much over 2 or 3 ipm (maybe).
Cooling is going to be critical! At that kind of rpm and feed any heat = broken bit.
Spindles:
http://www.hsd.it/home.asp or
http://www.pdscolombo.com/products.htmJust found this:
Fully guarding the machine and offering a remote video system for monitoring performance will also reduce operator fear and anxiety. High-speed milling is quite foreign to many of today's operators, and running a spindle at 25,000 or 30,000 rpm is vastly different from running at the 2,000 or 3,000 rpm that operators understand.
To assist in determining certain feeds and speeds for a selected machine, Tables 1 and 2 are reprinted with permission of the Robb-Jack Corporation and represent their recommendations for using their particular end mills for machining three different materials.
Table : Table 1 - Recommended feed rates for two-flute solid carbide end mills in aluminum (based on unlimited available horsepower).
DIAMETER CHIP LOAD FEED RATE AT FEED RATE AT FEED RATE AT
(INCHES) PER TOOTH 6,000 RPM 10,000 RPM 20,000 RPM
1/8 0.002 24.0 40.0 80.0
3/16 0.004 48.0 80.0 160.0
1/4 0.008 98.0 160.0 320.0
5/16 0.008 98.0 160.0 320.0
3/8 0.012 140.0 240.0 480.0
1/2 0.016 190.0 320.0 640.0
5/8 0.016 190.0 320.0 640.0
3/4 0.020 240.0 400.0 800.0
1 0.020 240.0 400.0 800.0
DIAMETER CHIP LOAD FEED RATE
(INCHES) R.P.M. PER TOOTH (IPM)
1/8 2,000 0.0007 16.8
3/16 8,500 0.0012 20.0
1/4 6,000 0.0017 20.0
5/16 4,900 0.0025 25.0
3/8 4,100 0.003 25.0
1/2 3,000 0.004 24.0
Table 2 - Recommended feed rates for roughing a slot in 6AL titanium (340 Brinell) with a two-flute solid carbide end mill (up to 5/16-inch diameter) at 400 sfpm. These recommendations apply to a depth of cut not to exceed one half of the cutter diameter. For cutters over 5/16 inch in diameter, depth of cut should not exceed one quarter of the diameter. For finishing cuts or profiling operations, use a four-flute end mill at double the listed feed rates.
Chad
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