When choosing the most suitable number of effective cutting edges, zc, for the operation, it is also essential to consider the pitch – the distance between the cutting edges.
Selecting the correct milling cutter pitch is important because it has a dramatic effect on productivity, stability and power consumption.
Number of cutting edges, zn
Cutter with high number of
By increasing the number of cutting edges, the table feed can be increased while retaining the same cutting speed and feed per tooth, without generating any more heat at the cutting edge.
However, increasing the number of edges changes the design of the tool. Shorter distances between tool edges means that there is less space left for chip evacuation and, in most cases, the cutter must be evenly pitched.
Power requirement is often a factor that limits the possible number of cutting edges that are engaged in cut.
Differential-pitched cutters have unequal spacing of the teeth around the cutter. These cutters are advantageous because they break up harmonic vibrations, which in turn increases stability and reduces the risk of vibration. This is especially useful when milling with a high width of cut, ae, and long overhangs.
Coarse, close and extra-close pitch
There are normally three different pitches to choose from that can help you optimize the application: coarse, close and extra-close pitches.
The closer pitch cutters are used when stability is good and for low ae applications. This ensures that more than one tooth always is engaged in cut.