JNTU B.Tech II Semester Examinations, FOUNDRY TECHNOLOGY, Apr/May 2008
(Metallurgy & Material Technology)
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
1. (a) Why is the casting yield in a steel foundry is considerably less than that of a gray iron or ductile iron foundry?
(b) What limits the largest casting that can be made by a molding process? Which molding process offers capability of producing very thin walled castings?.
(c) Evaluate casting processes which use no chemical binder with those foamed sand aggregate which can be readily poured to fill and form a mold. [6+5+5]
2. (a) Explain how vertically parted sand molds are made.
(b) Classify casting processes based on type of mold used.
(c) What are the merits, and demerits of core sand mold over green sand molds? [5+5+6]
3. (a) What defects are commonly observed in centrifugally cast parts? Explain them.
(b) Write short notes on :
i. Gravity die casting
ii. Centrifugal casting. [6+10]
4. (a) High strength molds require a lower feeder volume compared with a lower strength mold containing the cavity of same dimensions. Why is it so?
(b) Outline a procedure for deciding the riser dimensions and its location and their number for a given casting geometry?
(c) Why are risers mostly tapered cylinders of aspect ratio between 1.1 to 2.5. [5+6+5]
5. (a) Distinguish between homogeneous and heterogeneous nucleation for the solidification of a pure metal.
(b) Why is directional solidification essential in castings? Explain. [10+6]
6. (a) How much steel scrap can be charged in cupola? Discuss the limiting factors.
(b) What is divided blast cupola.
(c) What is chill-test?
(d) What inferences can be drawn by observing the fracture of cupola-slag?[5+5+3+3]
7. Discuss the low head type of continuous casting machine and discuss its applications. 
8. Discuss the casting defects which ma be directly attributed to the molding sand used for steel castings. Explain the remedial measures you would like to adopt to overcome these defects.