Feeds & Speeds

edited April 2013 in cnc
So...

I've got an 1/8" diameter, four flute, solid carbide end mill and I want to figure out speeds & feeds for the CNC Mill.  The datasheet at Production Tools says SFM (surface feet per minute) = 600 to 1200 @ 0.001 for Aluminum Alloys.  Using this link, the feeds & speeds calculator kicked out 18,335 RPM at 73.3 ipm (inches per minute).  Wow!  I don't think so.  Oh, and that was using SFM = 600 (the minimum).

Well, the Torq-Cut tops out at 7,500 RPM, so that's not an option.  Even at 7,500 RPM, the machine is crazy loud.

Luckily, the calculator also lets you enter desired RPM and it will reverse calculate SFM.  Below is table for the four flute 1/8" end mill from the calculator.

2000 RPM / 7.4 ipm
2500 RPM / 9.25 ipm
3000 RPM / 11.1 ipm
3500 RPM / 13 ipm

Reading some on Wikipedia, the following formula makes sense:

FR = RPM * T * CL   where FR = Feed Rate (ipm), T = # of Flutes, and CL = Chip Load (inches).

As an example, 3000 RPM * 4 Flutes * 0.001" Chip = 12 ipm   a bit higher than 11.1 ipm from the calculator.

My question, finally, is this: Do these calculation make sense.  Does 3000 RPM @ 12 ipm sound reasonable as a starting point?

If yes, I'm thinking of adding the Speeds & Feeds formula to the Torq-Cut i3 Wiki page.

Jim

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