[Paul_S]

End Cutting will always have a worse finish then the side cutting at the same feed. If you are trying to get a good finish on an end cut you must go much slower than you would use for a side cut.

If you know the angle on the bottom of the end mill you can calculate for a approximate finish.

I assume a 1.5 deg angle.

And I calculate for a 125 finish to start, and see how it looks.

I make my feed calculation as if I only have one flute cutting. (With a good end grind with a 2 of 4 flute the feed can be increased by the number of flutes maybe.)

For a 125 finish I calculate 250E-6/tan 1.5 x RPM

250E-6/tan 1.5 will give you a feed of .0095 per revolution.

For a 63 finish I calculate 126E-6/tan 1.5

Which gives me .0048

Again this is per revolution. Not per flute.

So for a 125 finish .0095 IPR
For 63 finish .0048 IPR
For 32 finish .0024 IPR

Now if the cutter has a radius on it, you can go a little faster and get the same or better finish.

To calculate a finish with tool radius, the method is more accurate and predictable.

Using the following equation:

Were the finish is for example 32 becomes 32E-6 ( 32. x 10^-6)

4 x sqr(32E-6x(radius - 32E-6)) = IPR

If you want closer to a Ra or RMS finish the correction is:

sqr(183/125) x 4 x sqr(32E-6 x (radius - 32E-6)) = IPR for a RMS type finish.
sqr(183/111.52) x 4 x sqr(32E-6 x (radius - 32E-6)) = IPR for an Ra finish

63 would be 63E-6 in the equation, 125 would be 125E-6 in the equation.

If a finish is not as good as you think it should be or an inspector says it isn't as good. Make a IPR correction as follows.

old IPM (or IPR) x sqr(finish wanted/known finish) = corrected IPM (or IPR)

For sharp end cutting tools, end cutting, use a direct ratio.

old IPM (or IPR) x (finish wanted/known finish) = corrected IPM (or IPR)

Note, all finish feed rates should be calculated by IPR not IPT.

Only end cutting one might be able to increase the feed per tooth. Only with ground EM. Otherwise always IPR.

I hope this info will help.

One more thing, some materals may require as much as 20% decress in feed. Which can be calculated/corrected as noted above.