t=LfNandV=πDN
∴t=LπDfV=900×π×2000.25×300×1000
=9π×230×0.25min=6π2.5min
=7.54min
A batch of 500 jobs of diameter 50mm and length 100mm is to be turned at 200rev/min and feed 0.2mm/rev The number of tool changes required to machine the whole batch is
Common Data: A disc of 200mm outer and 80mm inner diameter is faced at a feed of 0.1mm/rev with a depth of cut of 1mm. The facing operation is undertaken at a constant cutting speed of 90m/min in a CNC lathe The main (tangential) cutting force is 200N Assuming approach and over-travel of the cutting tool to be zero, the machining time in min is