Two 1 mm thick steel sheets are to be spot welded at a current of 5000 A. Assuming effective resistance to be 200 μm and current flow time of 0.2 second, heat generated during the process will be
Answer: D
Given: I = 5000 A, R = 200 μΩ = 200 × 10⁻⁶ Ω, Δt = 0.2 second
Heat generated, Hg = I 2(R Δt)
Hg = (5000)⊃2; × 200 × 10⁻⁶ × 0.2 = 1000 Joule
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NC contouring is an example of
Answer: A
NC contouring is a continuous path positioning system. Its function is to synchronize the axes of motion to generate a predetermined path, generally a line or a circular arc.
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A twist drill is a
Answer: C
No answer description available for this question.
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Which of the following parameters govern the value of shear angle in continuous chip formation?
Answer: D
No answer description available for this question.
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The object of caulking in a riveted joint is to make the joint
Answer: D
No answer description available for this question.
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A CNC vertical milling machine has to cut a straight slot of 10 mm width and 2 mm depth by a cutter of 10 mm diameter between points (0,0) and (100,100) on the XY plane (dimensions in mm). The feed rate used for milling is 50 mm/min, milling time for the slot (in seconds) is
Answer: B
Given data, width (b) = 10 mm, depth = 2mm
Distance travelled for cut between points (0, 0) and (100,100)
By Pythagoras theorem
d = √(100⊃2;+ 100⊃2;) = 141.42mm
Feed rate f = 50 mm/min = 50/ 60 = 0.833 mm/ sec.
Time required to cut the distance (d)
t = d/f = 141.42/ 0.833 = 169.7 ≈ 170 sec.
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The snag grinding is done
Answer: B
No answer description available for this question.
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In which type of welding a gas shield, a consumable electrode is used and the welding can be done in all positions.
Answer: D
In MIG welding, it’s a gas shield, a consumable electrode and can be done in all positions.
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Shrinkage allowance on pattern is provided to compensate for shrinkage when
Answer: C
Since metal shrinks on solidification and contracts further on cooling to room temperature, linear dimensions of patterns are increased in respect of those of the finished casting to be obtained. This is called the “shrinkage allowance”. So, the temperature of solid phase drops from freezing to room temperature.
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The main purpose of spheroidising treatment is to improve
Answer: D
Spheroidising may be defined as any heat treatment process that produces a rounded or globular form of carbide. High carbon steels are spheroidized to improve machinability, especially in continuous cutting operations.
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