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# THAPAR UNIVERSITY Metal Casting & joining,PPI312 DEC. 2014 PAPER Electronics and Communication Engineering (ECE) Notes | EduRev

## Electronics and Communication Engineering (ECE) : THAPAR UNIVERSITY Metal Casting & joining,PPI312 DEC. 2014 PAPER Electronics and Communication Engineering (ECE) Notes | EduRev

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.1 	 What are the causes of gas porosity in sand casting process and discuss the 04+05
mechanism for formation of gas porosity in the cast product by suitable
schematic diagrams.
In a particular mould design, the down sprue has an area of cross section 6.45
cm
2
where the pouring basin leads into the sprue. The sprue is 20 cm long. The
required metal flow rate at the top section of the sprue is 820 cm
3/sec. Determine
the pouring height necessary above the sprue top.
.2 The arc length characteristic of a DC arc is given by the equation V=24+4L,
where V is the arc voltage in volts and L is the arc length in mm. The static volt
ampere characteristic of the power source is approximated by a straight line with
no load voltage of 80 V and short circuit current of 600 amperes. Determine the
optimum arc length for maximum power.
What is the heat affected zone explain briefly with neat sketch. Write the process
parameters of arc welding which can affect it and how to minimize this.
05+04
Q.3 Discuss the different modes of metal transfer in gas metal arc welding process, 05+04
explain with suitable neat sketches.
Why welding of reactive materials like aluminium is difficult by GMAW or
SMAW process and how to overcome these problems while joining through
SMAW process.
Q.4 How the modes of metal transfer affect the weld characteristic, Discuss the 05+04
different arc forces acting on the molten droplet during welding explain with
suitable sketches.
Why the differential heat generation at anode and cathode during arc welding
process.
Q.5 	 Discuss the arc cleaning action by suitable sketches and also discuss the 06+03
principle of PAW and write the type of power source and polarity will be used?
What do you understand by weld decay and how to control it?
Roll Number:
Thapar University Patiala
Department of Mechanical Engineering
End Semester Examination, December, 2014
ME (P411)- (III Semester)
December, 2014
Time: 03 Hours; MM: 45
Note: Do all questions in sequence
PPI312:
Metal Casting & joining
Name of Faculty: Dr. Dheeraj Gupta
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