Question

QUESTION 1 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) = 15 in. The cutting speed = 300 ft/min, the penetration feed (z-direction) = 0.015 in/rev, and the traverse rate between holes (x-y plane) =15.0 in/min. Assume that x-y moves are made at a distance of 0.50 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° Determine the time required to retract drill from hole O 0.444 min 0 874 min 0.056 min 0.123 min

Answer 1

c) Time required to retract drill from hole is 0.056 min

Cutting speed is 300 So,

N= 1527.7

fr = 22.916

A = 0.315

Tm =0.112/2

time is 0.056 to retract drill from hole