You can adjust DOC, RPM, and IPM to any value that produces a removal rate
BELOW the rating of your spindle motor, and BELOW the FPM for the material
(Milling aluminum, about 300 FPM) with the cutter size you are using.

In general, an end mill shouldn't have a DOC more than it's fluted length, and
half the diameter, unless you absolutely have to plow a slot. If you're
plowing, the lengthwise DOC will determine the accuracy of the finished work.
Say 0.010 inch infeed steps for a typical key way: that means many passes but
gives a good fit so the key won't bend under loads.

Material removal rate is CIM, cubic inches per minute, and it takes about one
HP to remove one CIM in steel. You might get 2 CIM in aluminum, but just
because the FPM is 3 times higher than in steel, it does NOT mean the CIM will
be the same amount higher.

CIM divided by HP = Machinability, and the most machinable practical metals
are magnesium alloys, which can produce flammable chips easily. Save the chips
for Independence Day. The only thing that will put out an Mg fire is smothering
it with dry sand or adding a lot of carbon to it to soak up available oxygen.
Sorry, that's not right. What''s the Class D extinguisher? It's black, but it's
not carbon. Is it graphite? Or coke?

So your spindle has an RPM limit built in. Below that, your cutter diameter and
material gives you a FPM limit. The motor HP limit gives you a CIM limit, and
DOC and IPM feed (Dimensions of cut, not Depth of Cut, that is, an area, not a
linear measurement) multiply together to calculate actual CIM. Once selected,
FPM, DOC, and IPM imply tolerance. Easing off on any or all three gives you a
better tolerance. Pushing them to the max, if you stay in tolerance, gives
plenty of good parts at the best production rate. But each reject costs you one
machine cycle.

If you easy off FPM on a lathe, though, you can get stringy chips, which slow
production.

Got it?

So if anyone could explain it or give
me a formula it will greatly be appreciated.


I think this is one of the most concise posts I have written here. That's rare
for me. I have never set it down even for myself as well as this.





Yours,

Doug Goncz
Replikon Research (via aol.com)

Nuclear weapons are just Pu's way of ensuring that plenty of Pu will be
available for The Next Big Experiment, outlined in a post to
sci.physics.research at Google Groups under "supercritical"