Manufacturing Process 3 - Jun 2014

Mechanical Engg. (Semester 5)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks. 1 (a) Compare Hot working and Cold working processes.(8 marks) 1 (b) A Copper wire has a nominal breaking strength of 300MPa. Its ductility is 77% reduction of area. Calculate the true stress for fracture.(5 marks) 1 (c) Derive the equation for principle stresses.(7 marks) 2 (a) Discuss the effect of i) Friction ii) Lubrication on metal working process.(8 marks) 2 (b) Write a note on
i) Deformation zone geometry ii) Workability of materials iii) Residual stress in wrought products.(12 marks) 3 (a) Classify and explain the various forging process, with neat sketches.(8 marks) 3 (b) A circular bar of 150 mm diameter and 100 mm height is forged at room temperature between two flat dies to 25 mm height. Determine the yield strength, average die pressure , as well as maximum die pressures at the beginning of plastic deformation and at the end of compression. The yield strngth of the material is given as σ=100.0(0.0085+ε)^0.39 N/mm² and /mu=0.1.(12 marks) 4 (a) Explain the commonly used rolling mill arrangements in today's manufacturing industry(10 marks) 4 (b) A roll mill has roll diameter of 850mm. Calculate the maximum reduction possible in this mill if the coefficient of friction is 0.3. Determine the rolling load required to obtained 25% reduction of a metal strip of 35mm thickness using the same rolling mill, given the average yield strength of the metal as 180 Mpa and strip width as 690mm.(10 marks) 5 (a) Discuss redundant work and its estimation in drawing(10 marks) 5 (b) List and explain a few important process variables that affect the drawing force in wire drawing process.(6 marks) 5 (c) Explain tube drawing with a floating mandrel.(4 marks) 6 (a) Explain the sketches : i) Indirect extrusion ii) Hydro static Extrusion.(8 marks) 6 (b) Write a note on extrusion dies(4 marks) 6 (c) It is required to extrude an Aluminium alloy at 380°C through square dies from 140mm to 50mm diameter. The ram speed is 40mm/sec and the flow stress of the material at 380°C is 240 Mpa. Determine the extrusion force with the following data. Length of the billet is 450mm; semi-die angle is 45°; Coefficient of friction between work surface is 0.15.(8 marks) 7 (a) Explain the types of multi operation dies, with neat sketch(12 marks) 7 (b) Calculate the maximum punch force and the work done required to blank a steel washer 44.45mm outside diameter and 22.3mm inside diameter from a 1.59mm thick rectangular sheet with an ultimate shear of 432N/mm^{2>/sup> and the % penetration is 20%.}(8 marks) 8 (a) Discuss any 3 methods od production of powders.(6 marks) 8 (b) List the advantage and disadvantage of HERF.(8 marks) 8 (c) Explain: i) Electromagnetic forming ii) Hot Isostatic Pressing.(6 marks)