JNTU B.Tech Examinations, FOUNDRY AND WELDING, Aug/Sep 2008
Time: 3 hours Max Marks: 80
Answer any FIVE Questions
All Questions carry equal marks
1. A mechanized ductile iron captive foundry has to be set up with a capacity of 250
tons/day of output metal. It must have sections for core making, two automated
mold making and handling lines, a melting and casting bay, two induction melting
furnaces, separate scrap yards for returns, automated sand preparation and supply
and sand reclamation system, degating yard, a cleaning and grinding unit, a quality
control and inspection wing and an administrative block. Provide a schematic
sketch of foundry plant layout which, you think, provides for minimum material
handling and redundant work. 
2. (a) Define permeability of molding sand. How is it tested? Why this property is
important for molds and cores?
(b) What are the molding clays? How do you classify them?
(c) Explain how binding clay forms bridges between the sand grains and the water
and consequently develops strength. [6+4+6]
3. (a) What laboratory tests that are routinely done for cupola melt control? What
is the relevance of these tests?
(b) How is melt rate and liquid metal temperature and composition are controlled
in Cupola? What process parameter the operator has in control on adjusting
4. (a) Sketch schematically a gating system and explain the geometry, design considerations and role of different elements of it.
(b) Differentiate between progressive and directional solidification of castings.
5. (a) Explain the submerged arc welding process with a neat sketch.
(b) Differentiate between TIG welding and MIG welding processes. [8+8]
6. (a) Explain the ‘friction welding’ process used for welding of plastics giving details about
i. Principle of operation
ii. Equipment used
iii. Surface preparation
(b) Write down the advantages, limitations and applications of the above process. [10+6]
7. Explain why for the following
(a) Bakelite scrap is useless, while polyvinylchloride scrap can be recycled.
(b) thermoplastic polymers are flexible, where as thermosetting polymers are not.
(c) Polyethylene is harder and more rigid than phenol formaldehyde.
(d) During condensation polymerization water molecules are formed as by-product.
8. (a) Describe the atomization process for the production of metal powders. Differ-
entiate between water and gas atomization techniques.
(b) Briefly classify and describe various powder metallurgical compaction processes
enlisting their suitability for specific application. [8+8]