Project ForgeA slot of 25 mm × 25 mm is to be milled in a workpiece of 300 mm length using a side and face milling cutter of diameter 100 mm, width 25 mm, and having 20 teeth. For a depth of cut 5 mm, feed per tooth 0.1 mm, cutting speed 35 m/min and approach and over-travel distance of 5 mm each, the time required for milling the slot is __________ minutes (round off to one decimal place).
Explanation
N=V/(πD)=35,000/(π×100)≈111.4 rpm. Table feed Vf=N·fz·Z=111.4×0.1×20≈222.8 mm/min. Since the cutter width (25mm) matches the slot width but the slot is 25mm deep and the depth of cut is only 5mm per pass, 25/5=5 passes are needed. Distance per pass = 300+5+5=310mm; time per pass=310/222.8≈1.39 min. Total = 5×1.39≈6.96 min, i.e. within the 7-9 minute accepted range.
Source: GATE ME 2020 Session 1 (ME-1) (2020)
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