JNTU
JNTU B.Tech III MACHINE TOOLS Previous Question Paper (May/June - 2019 - R13)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks.
Part A
Explain various types of chips with neat sketches.
Answer
Chips are classified into three main types: Continuous chips (formed during ductile material machining with high speed and positive rake angle), Discontinuous chips (formed during brittle material machining or low speed with low rake angle), and Continuous chips with built-up edge (formed due to high friction and pressure at the tool-chip interface causing material to weld to the tool tip).
Explain the mechanisms of tool wear. What are its regions?
Answer
Tool wear mechanisms include Adhesion (welding of chip to tool), Abrasion (hard particles scratching the tool), Diffusion (atomic migration at high temperatures), and Oxidation. The wear regions are: Flank wear (on the clearance face), Crater wear (on the rake face), and Notch wear (at the depth-of-cut line).
What are different operations performed on lathe?
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What are work holding and tool holding devices explain one in each?
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Explain the working principle of shaper.
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State the difference among drilling, boring and reaming process.
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What are work holding devices in milling machine?
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What is meant by indexing? State the principle of direct indexing.
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How is grinding differs from other machining process?
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Give the characteristics of grinding abrasives.
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Part B
Consider the various forces acting on the chip, draw merchant force diagram. State the assumption made.
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Discuss about Tool life.
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Explain the ideal properties of cutting tool material.
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Explain the geometry of a single point cutting with help of neat sketch.
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Comparison between Turret lathe and capstan lathe.
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Why Chucks are used? List various types of chucks used in lathe.
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Explain the difference between single spindle and multi-spindle lathes.
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Explain the principal features of automatic lathes.
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Write the differences between shaping and planning machine.
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Estimate the machining time required in a shaper to machine a plate of 200 × 90 mm under the following conditions. Cutting speed = 13.3m/min feed = 0.57 mm/stroke, approach + overrun (longitudinal) =20mm, (lateral) = 4mm ratio of cutting speed to rapid return = 0.83.
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Show with neat sketch a twist drill and label the important features.
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Estimate the time required to machine a cast iron surface 250 mm long and 150 mm wide on a shaper with cutting-to-return ratio of 1/2. Use a cutting speed of 21 m/min, return speed by 42 m/min, a feed of 2 mm/stroke and a approach and overrun at each end is 25 mm.
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What do you mean by broaching? Explain principle related to broaching and types of broaching machines.
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Explain briefly about lapping and honing process.
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Explain with the help of neat sketch column and knee type milling machine.
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What is the difference between compound indexing and differential indexing?
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Describe the construction and working of tool and cutter grinding machine.
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Describe dressing and balancing in grinding.
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Mention various types of bonds used in making the grinding wheel also mention their application.
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What is meant cylindrical grinding machine, explain various types cylindrical grinding machines.
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