Evaluation of Cutting Parameters and Cutting Time:

Throughout turning operation on a lathe machine, the main cutting motion enables the cutting procedure (chip formation) to be accomplished, when the feed motion extends the cutting procedure to the entire surface to be machined on the workpiece (Figure 1) throughout both external turning and internal turning.

Cutting conditions (cutting speed - V, feed rate - f, & depth of cut - d), tool material (WC, H.S.S etc) and tool geometry (clearance angle, rake angle, etc) affect the procedure performance. The feed rate might be defined as linear movement of the tool in the feed direction in each of revolution (mm / rev.). Sometimes this is also indicated in terms of mm/s, or mm/min. It might be calculated (Eq. (1)) if spindle speed (revolutions per minute (RPM), or revolutions per second (RPS)) and feed rate in mm / rev. are known.

f_s (mm /s) = f_r (mm/rev.) × RPS          . . . (9.1)

Here, RPS is rotational speed of workpiece in revolutions per second.

Figure : Operation Showing Primary Cutting Motion

A feed rate (mm/rev) might be decided only from those feed rates that are available on the machine tool. Only restricted number of feed rates is available on any machine tool (exceptional is numerically controlled (NC) machine tools whereas bigger flexibility is available).