GTU previous question papers -BE- Sem-Vth – Manufacturing Processes-II -Nov/Dec-2011

GUJARAT TECHNOLOGICAL UNIVERSITY

BE SEM-V Examination-Nov/Dec.-2011

Subject code:  151901

Subject Name: Manufacturing Processes-II

Instructions:

1. Attempt all questions.

2. Make suitable assumptions wherever necessary.

3. Figures to the right indicate full marks.

Q.1 (a) What is pattern? List different types of patterns and explain

any two with neat sketch.

(b) Explain the following:

(i) Rapping allowances

(ii) Distortion allowances

Q.2 (a) List factors which affect salvaging of casting. Also list

various salvage techniques of casting and explain any one.

(b) Discuss: (i) Shell Moulding (ii) Die Casting

OR

(b) Explain the properties of moulding sand.

Q.3 (a) What determines whether a certain welding process can be

used for workpiece in a horizontal, vertical, or an upsidedown

position, or for all types of positions? Explain, giving

appropriate examples.

(b) Two flat copper sheets of 1.2mm thickness each are spot

welded. The process parameters are: current = 5000A,

Current flow time = 0.20second, and diameter of electrodes

= 6mm. Estimate the heat generated in the welding zone.

OR

Q.3 (a) Explain the factors involved in electrode selection in arc

welding processes.

(b) A steel tube of 76mm outer diameter and 4mm thickness is

welded to a flat piece by applying friction welding process

with the following information: Energy applied E=IS2/C,

where I= Moment of inertia of the flywheel, S = spindle

speed in rpm, C = proportionality constant = 250, weld

zone = 5mm deep, and energy required to melt the

electrode = 0.14kg-m. If the entire energy of the flywheel is

used to heat the electrode, what is the required moment of

inertia of the flywheel?.

Q.4 (a) Explain why there might be a change in density of a forged

product as compared to that of the cast blank.

(b) Explain how you would go about applying front and back tensions to sheet metals during rolling

OR

Q.4 (a) It was stated that the extrusion ratio, die geometry,

extrusion speed, and billet temperature all affect the

extrusion pressure. Explain why.

Q.4 (b) How would you go about preventing center burst defects in

extrusion? Explain why your methods would be effective.

Q.5 (a) With the aid of sketches, compare the principles of

compression moulding, injection moulding and extrusion

moulding. Describe where each would be used in terms of materials and components.

(b) Explain with sketch and application: Cylindrical and

Center less grinding process for finishing operation.

OR

Q.5 (a) Explain what is meant by term Inserts, and explain where

they are of use in plastic moulding. Sketch a typical

component showing the position of the Inserts and explain

their purpose.

(b) Explain: (i) Barrel Tumbling (ii) Polishing operation