Feed and Speed Steps:

In any conventional machine tool, the speed and feed vary in steps. The cutting conditions are found by selecting the highest permissible feed and then determine the corresponding speed from Eq. (12). From the tool life point of view, choose the lower speed (RPM) from the two closest values available on the machine tool.

For example, suppose the calculated RPM is 310 but the available speeds on the machine tool are 320 and 275. Then, choose 275 in place of 320 from the tool life consideration. It is not necessary to apply all the restrictions discussed above, at a time. Which restriction should be applied, is decided by the requirements of the job.