Three Elements of Milling

The cutting amount refers to the total term of the cutting speed v c, feed rate f (or feed rate v f), and back cutting amount a p, also known as the three elements of cutting amount. It is the process parameter required to adjust the relative motion speed and position between the tool and the workpiece. Their definitions are as follows:

（1） Cutting speed v c

The instantaneous speed of the selected point on the cutting edge relative to the main motion of the workpiece. The calculation formula is as follows:

V c=(π d w n)/1000 (1-1).

In the formula, v c - cutting speed (m/s).

Dw - The diameter of the surface to be machined on the workpiece (mm).

N - workpiece speed (r/s).

When calculating, the maximum cutting speed should be used, such as the numerical value of the surface diameter to be machined during turning, because the speed is highest and the tool wear is fastest here.

（2） Feed rate f

The relative displacement between the tool and the workpiece in the direction of feed motion during each revolution of the workpiece or tool.

The feed speed vf refers to the instantaneous speed at which a selected point on the cutting edge moves relative to the workpiece feed.

V f=fn (1-2).

In the formula, v f - feed rate (mm/s).

N - Spindle speed (r/s).

F - Feed rate (mm)

（3） The back bite rate is a p.

The cut measured in the direction perpendicular to the working plane through the cutting edge base point. According to this definition, if the outer circle of the longitudinal car is in the outer circle, its back cutting amount can be calculated as follows:

A p=(d w d m)/2 (1-3).

In the formula, d w - the diameter of the workpiece surface to be machined (mm).

DM - The diameter of the machined surface of the workpiece (mm).