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.

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.

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