JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III MACHINE TOOLS Previous Question Paper (January/February - 2023 - R13)
Question paper consists of Part A and Part B. Part A is compulsory (25 marks). Part B (50 marks) requires answering any one question from each unit.
Part A
What is the function of a chip breaker?
Answer
The primary function of a chip breaker is to break long, continuous chips into smaller, manageable pieces. This prevents the formation of dangerous long chip coils, protects the operator, avoids damage to the workpiece surface finish, and facilitates easier chip disposal.
Define tool life. State the factors which effect tool life.
Answer
Tool life is defined as the actual cutting time a tool can perform effectively between two successive sharpenings. Factors affecting tool life include cutting speed, feed rate, depth of cut, tool material, workpiece material, tool geometry, and the use of cutting fluids.
Why are engine lathes called by that name?
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Explain the working principle of lathe.
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What are the advantages of twist drill?
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Give comparison between planer and shaper.
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State the advantages of down milling process?
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Compare grinding, lapping, and honing.
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How is grinding ratio defined?
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Enumerate the special features of grinding process.
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Part B
Give the comparison between orthogonal cutting and oblique cutting with neat sketches.
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With the help of neat sketches, explain briefly the tool elements and tool angles in case of single point cutting tool.
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What is chip thickness ratio? Discuss briefly the basic mechanism of chip formation.
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During orthogonal cutting a bar of 75mm diameter is reduced to 73mm. If the mean length of the cut chip is 73.5 mm and rake angle is 15 degrees, calculate (i) Cutting ratio (ii) Shear angle.
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What factors govern the classification of lathes? Describe in brief the various types of lathes.
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Describe the taper turning attachment of a lathe. What are its merits and demerits over other methods of taper turning?
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Describe the different methods of feeding the tool in screw cutting.
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How threading tools are set for internal and external threading? Explain.
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Explain the working of a quick return mechanism of a shaper.
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A C.I. plate measuring 300 mm × 100 mm × 40 mm is to be rough shaped along its wider face. Calculate the machining time taking approach = 25mm, Overtravel = 5 mm, cutting speed = 12m/min, return speed = 20m/min allowance on either side of the plate width = 5mm and feed per cycle = 1mm.
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Enumerate the work holding devices used in drilling machines.
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Explain briefly a jig boring machine, with a neat sketch.
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Explain the effects of various angles of the teeth of a plain milling cutter with help of neat sketch.
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What are the different indexing methods? Explain about angular indexing.
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Explain the terms speed, feed and depth of cut as applicable to grinding work.
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What is the purpose of honing? List the advantages, disadvantage and applications.
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Explain the principle of centerless grinding. Explain through feed, infeed and end feed methods of centerless grinding.
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What are the different abrasives used in grinding process. Explain.
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How does the area of contact affect grinding wheel selection? Explain.
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Differentiate grain and grade in a grinding wheel.
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