Always do research on the material you are going to cut! The feedrate and spindlespeed are highly dependent on material, cuttertype and setup. Remember that machining is a dynamics problem, things are spinning, flexing and shearing. The key to a well machined part is a rigid setup, appropriate lubrication and proper cutting forces.
Feed and Speed
Whether using the drill press or the milling center it is important to select the correct spindle speed. Spindle speed is specified in RPM (revolutionsperminute) and can be calculated based on the cutter diameter and the material from tables. Tables usually list feedrate in SFM (surfacefeetperminute), which can be converted into RPM using the following formula, where the diameter of the tool is in inches:
RPM = [ 12 x SFM ] / [ PI x ( tool diameter ) ]
Similarly you can determine the feedrate in IPM (inchesperminute) given a specified IPR (inchesperrevolution) from a table using the following formula:
IPM = ( # of teeth in the cutter x IPR ) x RPM
So for example if you were going to cut aluminum with a 3/8" HSS 2 flute endmill you would want to start with a spindle speed of (12*300) / (3.1416*0.375) = 3056 RPM and feed rate of (2*0.001)*3056 = 6.1 IPR.
Material 
Speed (SFM) 
Feed (IPR) 
Aluminum 
300 
0.001 
Brass 
200 
0.001 
Mild Steel 
100 
0.001 
Stainless Steel 
50 
0.001 
Teflon 
250 
0.002 
