JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III FABRICATION PROCESSES Previous Question Paper (October - 2020 - R16)
Answer any five questions. All questions carry equal marks.
Illustrate your answers with NEAT sketches wherever necessary.
Main
Explain the ‘sweep pattern’, and mention its applications.
Answer
A sweep pattern is a specialized type of pattern used to generate surfaces of revolution, such as large circular or cylindrical castings, without requiring a full-sized solid pattern. It consists of a wooden board or template shaped to the profile of the desired casting, which is attached to a vertical spindle or central axis. As the spindle rotates, the board sweeps through the molding sand, carving out the cavity in the mold.
Applications include:
- Production of large circular or cylindrical components like bells, pipes, and large gears.
- Manufacturing of molds for large circular tanks or circular bases.
- Situations where creating a full solid pattern is economically unfeasible due to the large size of the casting.
A casting of plain carbon steel is to be made using a wooden pattern. The casting is a rectangular prism with 140 × 200 mm base and 80 mm height. It has a central through hole of 70 mm dia. Calculate the dimensions of the wooden pattern which is to be used to make the casting, and draw a free hand sketch of the pattern showing the various dimensions. Shrinkage allowance may be neglected.
Answer
Since shrinkage allowance is neglected, the pattern dimensions are identical to the casting dimensions. The casting is a rectangular prism (140 mm × 200 mm × 80 mm) with a central through-hole (70 mm diameter). To create this, the pattern must be a solid rectangular block with a core print to accommodate the core for the hole.
Pattern dimensions:
- Length: 200 mm
- Width: 140 mm
- Height: 80 mm
- Core print: A cylindrical projection or recess is required to support the 70 mm diameter core.
Sketch description: Draw a rectangular block of 200 mm (length) by 140 mm (width) by 80 mm (height). At the center of the top and bottom faces, indicate circular core prints of 70 mm diameter to ensure the core is held in position during metal pouring.
List the different properties of molding sand and explain any four.
Answer
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Explain the principles of design of risers.
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With a neat sketch, explain the process of Thermit welding. What are its applications?
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What is Explosive welding, and in what applications it is used?
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Compare and contrast TIG welding and MIG welding based on (i) material thickness, and (ii) ease of control. When should you prefer one of these two welding techniques over the other?
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What is ‘forge welding’? When is it used?
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Describe various types of pressures used in mechanical working.
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Give a complete comparison of hot working vs cold working.
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What is coining? Compare and contrast hot and cold coining.
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What are the different drawing processes? With a neat sketch, describe the deep drawing process.
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How are collapsible tubes of aluminium (like toothpaste tubes) manufactured? Explain.
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Distinguish between the forces encountered in forward extrusion and backward extrusion.
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What is meant by bulk deformation? Explain the different types of forging processes with sketches.
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What do you understand by ‘flash’ in forging? Explain with a sketch.
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