City Guilds Model Questions Vol1 2019 Engineering Question 25

A CNC milling operation must remove material from a steel workpiece that is \(200\) mm long, \(50\) mm wide and \(10\) mm thick. The cutter is a carbide end‑mill of diameter \(10\) mm with four teeth. The recommended cutting speed for the steel is \(120\) m/min and the feed per tooth is \(0.08\) mm. (a) Calculate the required spindle speed in rpm. (b) Assuming a single‑pass depth of cut equal to the cutter diameter and 100 % material removal per pass, determine the total number of cutter revolutions needed to clear the whole workpiece. (c) Using the Taylor tool‑life equation \(V T^{n}=C\) with \(V=120\) m/min, \(n=0.25\) and \(C=150\), estimate the tool life \(T\) in minutes and state whether a single tool will survive the operation.