A through hole is drilled in a steel plate 15 mm thick with a 20 mm twist drill of point angle 118°. The cutting speed is 0.5 m/s and the feed 0.22 mm/rev. Taking the approach A = 0.5D tan(90° − θ/2), determine (a) the machining time in s and (b) the metal removal rate in mm³/s once the drill reaches full diameter.