Object:True Rake and Inclination Angle(Cutting edge inclination) are calculated from R.R. and A.R..
R.R. and A.R. shows the characteristic of a milling cutter.
Four combinations of R.R. and A.R. are shown as follows;

1. posi-posi (double positive): R.R. and A.R. are positive.
2. nega-posi: R.R. is negative and A.R. is positive.
3. posi-nega: R.R. is positive and A.R. is negative.
4. nega-nega (double negative): R.R. and A.R. are negative.

General combinations are posi-posi, nega-posi and nega-nega.
Following equations show characteristics of these combinations.

\( \tan \left( \theta _ {T.R.} \right) = \tan \left( \theta _ {A.R.} \right) \times \sin \left( \theta _ {A.A.} \right) + \tan \left( \theta _ {R.R.} \right) \times \cos \left( \theta _ {A.A.} \right) \)
\( \tan \left( \theta _ {I.A.} \right) = \tan \left( \theta _ {A.R.} \right) \times \cos \left( \theta _ {A.A.} \right) - \tan \left( \theta _ {R.R.} \right) \times \sin \left( \theta _ {A.A.} \right) \)

Above mentioned equations are written in some cutting tool maker's catalogue.
T.R. and I.A. are calculated from R.R. and A.R..
T.R. becomes larger, cutting forces become smaller.
I.A. bocomes larger, chip evacuation becomes better. Because of large chip flow angle.
By using above mentioned equations, characteristics of cutters are explained as follows;

1. posi-posi:T.R. becomes large. Thus, this cutter is sharpe.
2. nega-posi:If the cutter's approach angle is large, I.A. becomes large. Thus, the chip evacuation is good.
3. posi-nega:I can not find advantage. I.A. is the smallest.
4. nega-nega:Characteristics of the major edge is worse than those of posi-posi and nega-posi. But, double-sided inserts can be used.