GATE ME Machining and Machine Tool Operations PYQs & Answers — Page 4

Questions 31–40 of 63. Imported answers require independent review unless marked reviewed.

A slot of 25 mm × 25 mm is to be milled in a workpiece of 300 mm length using a side and face milling cutter of diameter 100 mm, width 25 mm and having 20 teeth. For a depth of cut 5 mm, feed per tooth 0.1 mm, cutting speed 35 m/min and approach and over travel distance of 5 mm each, the time required for milling the slot is ______ minutes (round off to one decimal place).

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A cylindrical bar with 200 mm diameter is being turned with a tool having geometry 0° - 9° - 7° - 8° - 15° - 30° - 0.05 inch (Coordinate system, ASA) resulting in a cutting force

. If the tool geometry is changed to 0° - 9° - 7° - 8° - 15° - 0° - 0.05 inch (Coordinate system, ASA) and all other parameters remain unchanged, the cutting force changes to

. Specific cutting energy (in J/mm

) is

, where

is the specific energy coefficient, and

is the uncut thickness in mm. The value of percentage change in cutting force

, i.e.

, is ______ (round off to one decimal place).

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There are two identical shape machines S

and S

. In machine S

, the width of the workpiece is increased by 10% and the feed is decreased by 10%, with respect to that of S

. If all other conditions remain the same then the ratio of total time per pass in S

and S

will be ______ (round off to one decimal place).

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In a turning process using orthogonal tool geometry, a chip length of 100 mm is obtained for an uncut chip length of 250 mm.

The cutting conditions are: cutting speed = 30 m/min, rake angle = 20°.

The shear plane angle is ______ degrees (round off to one decimal place).

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Bars of 250 mm length and 25 mm diameter are to be turned on a lathe with a feed of 0.2 mm/rev. Each grinding of the tool costs Rs. 20. The time required for each tool change is 1 min. Tool life equation is

(where cutting speed

is in m/min and tool life

is in min). The optimum tool cost per piece for maximum production rate is Rs. ______ (round off to 2 decimal places).

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A point ‘P’ on a CNC controlled XY- stage is moved to another point ‘Q’ using the coordinate system shown in the figure below and rapid positioning command (G00). A pair of stepping motors with maximum speed of 800 rpm, controlling both the X and Y motion of the stage, are directly coupled to a pair of lead screws, each with a uniform pitch of 0.5 mm. The time needed to position the point ‘P’ to the point ‘Q’ is ______ minutes (round off to 2 decimal places).

Diagram for Mechanical Engineering question 46

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The length, width and thickness of a steel sample are 400 mm, 40 mm and 20 mm, respectively. Its thickness needs to be uniformly reduced by 2 mm in a single pass by using horizontal slab milling. The milling cutter (diameter: 100 mm, width: 50 mm) has 20 teeth and rotates at 1200 rpm. The feed per tooth is 0.05 mm. The feed direction is along the length of the sample. If the over-travel distance is the same as the approach distance, the approach distance and time taken to complete the required machining task are

Your answerChoose one option.

14 mm, 18.4 s

21 mm, 28.9 s

21 mm, 39.4 s

14 mm, 21.4 s

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The cold forming process in which a hardened tool is pressed against a workpiece (when there is relative motion between the tool and the workpiece) to produce a roughened surface with a regular pattern is

Your answerChoose one option.

Roll forming

Strip rolling

Knurling

Chamfering

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In an electrical discharge machining process, the breakdown voltage across inter electrode gap (IEG) is 200 V and the capacitance of the RC circuit is 50 μF. The energy (in J) released per spark across the IEG is _____

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In orthogonal turning of a cylindrical tube of wall thickness 5 mm, the axial and the tangential cutting forces were measured as 1259 N and 1601 N, respectively. The measured chip thickness after machining was found to be 0.3 mm. The rake angle was 10° and the axial feed was 100 mm/min. The rotational speed of the spindle was 1000 rpm. Assuming the material to be perfectly plastic and Merchant’s first solution, the shear strength of the material is closest to

Your answerChoose one option.

722 MPa

920 MPa

200 MPa

875 MPa

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GATE ME Machining and Machine Tool Operations PYQs

Question 42

Question 43

Question 44

Question 45

Question 45

Question 46

Question 15

Question 16

Question 25

Question 35