GATE PI topic:machining PYQs & Answers — Page 3

Questions 21–30 of 34. Imported answers require independent review unless marked reviewed.

Topic practice 34 questionsPage 3 of 4

The top layer of a flat 750 mm × 300 mm rectangular mild steel plate is to be machined with a single depth of cut using a shaping machine. The plate has been fixed by keeping 750 mm side along the tool travel direction. If the approach and the over-travel are 25 mm each, average cutting speed is 10 m/min, feed rate is 0.4 mm/stroke, and the ratio of return time to cutting time of the tool is 1:2, the time (in minutes) required to complete the machining operation is ________. [round off to one decimal place]

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Self-sharpening tendency of a conventional grinding wheel depends upon

Your answerChoose one option.

wheel structure

wheel grade

grit hardness

grit size

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A vertical boring operation is performed in a cast iron plate to enlarge a blind hole to a diameter of 25 mm up to a depth of 100 mm in a single pass. The cutting speed and the feed used in the process are 100 m/min and 0.1 mm/rev, respectively. Considering the allowance for tool approach as 2 mm, the actual machining time (rounded off to two decimal places) in minutes is ________________.

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For a particular tool-workpiece combination, the value of exponent

in Taylor’s tool life equation is 0.5. If the cutting speed is reduced by 50% keeping all the other machining conditions same, the increase in tool life in % is ____________.

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In a typical turning tool life test, the following data are generated for tools A and B:

Tool name	Cutting speed (m/min)	Tool life (min)
A	200	20
B	150	58

Assuming the same tool life exponent for the tools, the value of constant in the Taylor’s tool life equation (with cutting speed in m/min and tool life in min) is _____ (round off to 2 decimal places)

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A 20 mm HS drill with a point angle of 118° is used for drilling a through hole on a metallic plate of thickness 100 mm with a cutting speed of 333.33 mm/s and feed of 0.22 mm/rev. Assuming that the drill is touching the surface of the plate at the start, the drilling time (in s) is closest to

Your answerChoose one option.

100

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During a turning operation of a specific work material having shear strength of 220 MPa under orthogonal cutting condition, the process parameters are:

Parameter	Value
Feed	0.2 mm/rev
Depth of cut	1 mm
Rake angle	−5°

Given chip thickness ratio as 0.5, friction angle as 49.2° and shear angle as 25.4°, the feed force (in N) is ______

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A double-start thread with a pitch of 2 mm is to be cut using a lathe machine. The pitch of the leadscrew of the lathe is 6 mm. The job rotates at 60 revolution per minute (RPM). The RPM of the leadscrew is ______

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A cylindrical workpiece is turned at a feed of 0.1 mm/rev with a perfectly sharp tool. In ASA system, the side and end cutting edge angles are 15° and 5°, respectively, as shown in the figure. The peak-to-valley roughness (in

m, up to one decimal place) of the machined surface is _____

Diagram for Production and Industrial Engineering question 50

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During orthogonal machining of a job at a cutting speed of 90 m/min with a tool of 10° rake angle, the cutting force and thrust force are 750 N and 390 N, respectively. Assume a shear angle of 35°. The power (in W) expended for shear along the shear plane is _____

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GATE PI topic:machining PYQs

Question 47

Question 16

Question 46

Question 47

Question 21

Question 34

Question 49

Question 25

Question 50

Question 52