JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B. Tech III MANUFACTURING PROCESS AND MACHINE TOOLS Previous Question Paper (August - 2022 - R16)
Answer any five questions. All questions carry equal marks.
Main
Briefly explain investment casting with neat sketch. Also give its limitations and applications.
Answer
Investment casting, also known as lost-wax casting, is a precision casting process used to produce complex shapes with excellent surface finish and dimensional accuracy. The process involves creating a wax pattern, coating it with a ceramic slurry to form a mold, melting out the wax, and pouring molten metal into the cavity.
The process steps are: 1. Wax pattern production. 2. Assembly of patterns onto a central wax sprue. 3. Repeated dipping of the assembly into ceramic slurry and stuccoing to build a shell. 4. Dewaxing (melting out the wax in an oven). 5. Firing the ceramic mold. 6. Pouring molten metal. 7. Breaking the shell and finishing the part.
Applications: Used for turbine blades, dental implants, jewelry, firearms components, and intricate machine parts requiring high precision.
Limitations: High cost per unit, limited to smaller parts, long production cycle time due to mold preparation, and not suitable for very large castings.
Sketch and explain various die casting process. Also give their limitations and applications.
Answer
Die casting is a metal casting process characterized by forcing molten metal under high pressure into a mold cavity (die). There are two primary types: Hot Chamber and Cold Chamber.
Hot Chamber Die Casting: The metal melting pot is an integral part of the machine. A plunger forces molten metal directly from the pot into the die. It is used for low-melting-point alloys like zinc, tin, and lead.
Cold Chamber Die Casting: Molten metal is ladled into a cold chamber from an external furnace before being injected into the die by a plunger. This is used for high-melting-point alloys like aluminum, magnesium, and copper alloys to prevent damage to the injection system.
Applications: Automotive engine blocks, transmission cases, household appliances, and complex thin-walled components.
Limitations: High initial tooling and equipment costs, limited to non-ferrous metals, porosity issues due to trapped air, and restricted to smaller or medium-sized parts.
Explain the principle, advantages and applications of Gas metal arc welding.
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Discuss solid state welding processes in detail with sketch.
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Explain the following with suitable examples and sketches:
i) Strain hardening
ii) Recrystallization
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Classify the different types of rolling arrangements. Also explain the concept of rolling force.
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Distinguish between wire drawing and tube drawing. Also give their applications.
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Explain the characteristic features of sheet metal used in forming process.
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Sketch and explain the Impact extrusion and hydrostatic extrusion.
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Explain different types of extrusion processes with sketches. Also list out product applications of each process.
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Explain different types of forging processes with sketches. Also list out product applications of each process.
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Discuss in detail the open die and closed die forging process. Also give their applications.
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Draw Merchant’s Circle Diagram and derive expressions to show the relationships among the different forces acting on a cutting tool and different parameters involved in metal cutting.
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Write any four operations that can be performed on a lathe machine with diagrams.
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Sketch and describe about a Horizontal milling machine.
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What is the use of cylindrical grinders? Explain the principle of cylindrical grinding.
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