10. What is meant by a feed rate? 17. What are the general recommendations for cutting depths for turning and boring? 18. What are the general recommendations for cutting depths for milling? 20. Why is it important to calculate machining times? 11. A hole of 12mm and 25 mm depth is to be drilled using an HSS drill for a medium carbon steel. For average metal cutting conditions, determine: (i) suitable speeds (rpm) and feeds (mmrev); (ii) the time to machine the hole. 3. A 40mm HSS face mill is being used to machine grey cast iron. Det- ermine a suitable speed in revmin" for average metal cutting conditions.