JNTU B.Tech Examinations, FOUNDRY AND WELDING, Aug/Sep 2008

JNTU B.Tech Examinations, FOUNDRY AND WELDING, Aug/Sep 2008

(Production Engineering)

Time: 3 hours Max Marks: 80

Answer any FIVE Questions

All Questions carry equal marks

SET-II

1. (a) When does metal casting become attractive against a wrought product of same

shape?

(b) When do you use a sweep pattern?

(c) Differentiate between an automated foundry and mechanized foundry.

(d) Define permeability of molding sand? How is it tested? Why molds and cores

need to be permeable. [3+3+5+5]

 

2. (a) Discuss the use of polymer resins as binder of molding and core sands.

(b) Explain how strength is conferred in sodium silicate bonds. [10+6]

 

3. (a) Sketch cross section of cupola furnace and label different zones. What physical

and chemical changes occur in these zones when cupola is operated?

(b) What measures do you suggest to improve the thermal efficiency of a cold

blast cupola. [10+6]

 

4. (a) Explain how alloys solidify?

(b) Explain how microshrinkage and microsegregation are developed in solidified

parts?

(c) What are the pros and cons of using several ingates instead of single ingate in

feeding a mold cavity, when total ingate area is same in both cases? [4+6+6]

 

5. (a) Sketch the neutral flame for oxy acetylene welding and explain the chemical

reactions taking place in various zones of the flame. Also compare this with oxidising and carburising flames.

(b) Explain how acetylene gas is stored in the cylinder with a sketch, showing the

cross section of the cylinder. Discuss the safety devices incorporated on the

cylinder. [10+6]

 

6. (a) What is prime? What are the various types of primers used in adhesive bonding process. Explain them.

(b) Explain why primers are used in adhesive bonding process.

(c) Explain the following with regard to adhesive bonding process.

i. Surface preparation

ii. Curing the assembly which is adhesive coated. [6+5+5]

 

7. (a) What effects does a plasticizing agent have on a polymer? Explain in detail.

 (b) Give applications for which flammability of plastics would be of major importance. Also explain why?

(c) What properties do elastomers have that thermoplastics in general do not

have. Discuss. [8+4+4]

 

8. (a) Explain the following in detail:

i. Apparant density

ii. Sedimentation

iii. Compressibility

iv. Permeability

v. Flow rate.

(b) The property of the final sintered compact depends on the physico-chemical

characteristics of the metal powders used. Discuss. [10+6]

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