A NC drill press is to perform a series of through-hole drilling operations on a 1.75 in thick
aluminum plate that is a component in a heat exchanger. Each hole is 3/4 in diameter. There are
100 holes in all, arranged in a 10 by 10 matrix pattern, and the distance between adjacent hole
centers (along the square) = 1.5 in. The cutting speed = 300 ft/min, the penetration feed
(z-direction) = 0.015 in/rev, and the feed rate between holes (x-y plane) = 15.0 in/min. Assume
that x-y moves are made at a distance of 0.5 in above the work surface, and that this distance
must be included in the penetration feed rate for each hole. Also, the rate at which the drill is
retracted from each hole is twice the penetration feed rate. The drill has a point angle = 100
degrees. Determine the time required from the beginning of the first hole to the completion of the
last hole, assuming the most efficient drilling sequence will be used to accomplish the job.