As the spindle speed differs according to a work material, there is a difference about a lateral feed rate. In the case of hard and brittle materials, 0.1-0.5µm is recommended. Harder the work material slower the spindle speed, and lateral feed rate is made smaller.
In case of work material with hard and brittle material, it is sufficient with that of 10,000 min-1 or so. As there is no need to worry about the discharge of chips, it may possible to operate with a higher rotation according to a performance of machine, but it may need to pay attention to the sliding phenomenon at the cutting point according to a work material.