Diamond wheels should not be used for grinding steel components

To get good surface finish on a turned job, one should use a sharp tool with a ......... Feed rate and ............... Speed of rotation of the job.

In horizontal milling process ............................ (up/down) milling provides better surface finish and .............................. Up/down ) milling provide longer tool life.

If the longitudinal feed in center-less grinding is expressed by
$${V_f} = \pi \,D.\,\,N\,\sin \,\alpha ,\,\,D$$ stands for