The end of a large tubular workpart is to be faced on a NC vertical boring mill. The part has an outside diameter = 45.0 in and inside diameter = 25 in. If the facing operation is performed at a rotational speed = 30 rev/min, feed = 0.020 in/rev, and depth = 0.150 in, determine: (a) the cutting time to complete the facing operation, (b) the cutting speeds and metal removal rates at the beginning and end of the cut.