JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III FABRICATION PROCESSES Previous Question Paper (November/December - 2018 - R16)
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 and may have a, b, c as sub questions.
PART - A
(25 Marks)
What is the role of clay in moulding sand?
Answer
Clay acts as a binder in moulding sand, providing the necessary green strength and dry strength to the sand grains so that the mould retains its shape after the pattern is removed and during metal pouring.
What are the factors to be considered before selecting the material for a pattern?
Answer
Key factors include the number of castings required, the complexity of the casting shape, the required dimensional accuracy and surface finish, the cost of the material, and the resistance of the material to wear, moisture, and chemical reaction with the molten metal.
Explain various types of welds.
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Explain the mechanism of metal transfer in MIG welding.
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What is the significance of recrystallization temperature in metal working?
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What are the various types of dies used in press working?
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List out the advantages of extrusion.
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Explain methods to reduce forces required in extrusion.
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What are the main characteristics of hot forging as compared with cold forging?
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What is the importance of grain flow pattern in forging? Explain.
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PART - B
(50 Marks)
Explain the steps involved in investment casting.
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Explain various steps involved in design of gating system.
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Explain the significance of various pattern allowances.
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Calculate the size of a cylindrical riser (Height and diameter equal) necessary to feed a slab casting 45 × 45 × 25 cm with a side riser, casting poured horizontally in to the mould. Use caine’s equation and take constants in caine equation as a = 0.18, b = 0.05 and c = 1.0.
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Explain the effect of polarity on penetration in DC arc welding.
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Describe with neat sketches the TIG welding method and give its specific applications.
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With the help of a neat sketch of welding torch explain the oxy acetylene process of welding.
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With the help of a neat sketch explain the principle of laser welding.
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What are the similarities and differences between piercing and blanking?
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With the help of neat sketch explain the process of spinning. What are the advantages of spinning process?
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What is coining? Explain the process with the help of a neat sketch.
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A cup of 50mm diameter and 20mm height is to be produced by drawing from a 1.5mm thick sheet metal. Find the blank diameter and the maximum drawing force. Assume ultimate strength of sheet metal to be 650MN.
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Derive an equation for ideal extrusion pressure.
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Write a note on impact extrusion and list the advantages of impact extrusion over other extrusion processes.
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Explain the effect of speed of deformation and friction on extrusion pressure.
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How direct extrusion differs from indirect extrusion? Discuss their relative merits and demerits.
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Explain the various forging operations and list the forging defects.
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A 20cm thick plate is flat forged to decrease thickness in steps to 10cm and 5cm. Determine total strain based on initial and final dimensions and also on the summation of the incremental strains using engineering strain and true strain. Give conclusion.
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What are the advantages and limitations of smith forging?
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Explain the process of closed die forging. Explain the importance of flash.
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