Past Year Questions: Joining Processes Mechanical Engineering Notes | EduRev

Manufacturing and Industrial Engineering

Mechanical Engineering : Past Year Questions: Joining Processes Mechanical Engineering Notes | EduRev

The document Past Year Questions: Joining Processes Mechanical Engineering Notes | EduRev is a part of the Mechanical Engineering Course Manufacturing and Industrial Engineering.
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Question 1:A 900 mm long steel plate is welded by manual metal arc welding process using welding current of 150 A, arc voltage of 20 V and welding speed of 300 mm/min. If the process efficiency of is 0.8 and surface resistance is 36 micro-ohm, the heat input in J/mm

[PI 2003]

Question 2:In resistance welding, heat is generated due to the resistance between

[PI 2003]

Question 3:The type of weld represented by the shaded region in the figure is

[ME 2018,Set-1]

Question 4:Two pipes of inner diameter 100 mm and outer diameter 110 mm each are joined by flash butt welding using 30 V power supply. At the interface, 1 mm of material melts from each pipe which has a resistance of 42.4 ohms. If the unit melt energy is 64.4 MJ/m3, then time required for welding (in s) is

[ME 2010]

Question 5:Spot welding of two 1 mm thick sheets of steel (density = 8000 kg/m3) is carried out successfully by passing a certain amount of current for 0.1 second through the electrodes. The resultant weld nugget formed is 5 mm in diameter and 1.5 mm thick. If the latent heat of fusion of steel is 1400 kJ/kg and the effective resistance in the welding operation is 200 μ-ohms, the current passing through the electrodes is approximately

[ME 2005]

Question 6:The strength of a brazed joint

[ME 2005]

Question 7:Resistance spot welding is performed on two plates of 1.5 mm thickness with 6 mm diameter electrode, using 15000 A current for a time duration of 0.25 sec. Assuming the interface resistance to be 0.0001 ohms. The heat generated to form the weld is

[ME 2001]

Question 8:For resistance spot welding of 1.5 mm thick steel sheets, the current required is of the order

[ME 1991]

Question 9:Which of the following welding process results in the smallest heat affected zone?

[PI 2011]

Question 10:During a steady gas metal arc welding with direct current electrode positive polarity, the welding current, voltage and weld speed are 150 A, 30 V and 6 m/min respectively. A metallic wire electrode of diameter 1.2 mm is being fed at a constant rate of 12 m/min. The density, specific heat and melting temp of the wire electrode are 7000 kg/m3, 500 J/kg and 1530°C respectively.
Assume the ambient temp to be 30°C and neglect the latent heat of melting. Further consider that 2/3rd of the total electrical power is available for melting of the wire electrode. The melting efficiency (in percentage) of the wire electrode is

[PI 2010]

Question 11:Autogeneous gas tungsten arc welding of a steel plate is carried out with welding current of 500 A. Voltage of 20 V and weld speed of 20 mm/ min. Consider the heat transfer efficiency from the arc to the weld pool as 90%. The heat input per unit length (in kJ/mm) is

[PI 2009]

Question 12:The DC power source for are welding has the characteristic 3V + I = 240, where V = Voltage and I = Current in amp. For maximum are power at the electrode, voltage should be set at

[PI 2007]

Question 13:The current in Amperes used in resistance spot welding of plain carbon steel sheets (1 to 3 mm thick) lies within the range

[PI 2004]

Question 14:Which of the following process can be used for welding of Aluminum alloys?
P. Submerged arc welding
Q. Gas metal arc welding
R. Electroslag welding
S. Gas tungsten arc welding

[PI 2003]

Question 15:The voltage arc length characteristics of a DC arc is given by V = 20 + 40L, where L = arc length in cm. The power source characteristics can be approximated by a straight line. Open circuit is 80 V and short circuit current 1000 Amps. The optimum arc length in mm

[PI 1991]

Question 16:High alloy steel components are preheated before welding for reducing

[PI 1991]

Question 17:The mode of metal transfer in CO2-MIG welding at low temperature is

[PI 1990]

Question 18:In an arc welding process, welding speed is doubled. Assuming all other process parameters to be constant, the cross sectional area of the weld bead will

[ME 2017,Set-1]

Question 19:The welding process which uses a blanket of fusible granular flux is

[ME 2016,Set-2]

Question 20:During a TIG welding process, the arc current and arc voltage were 50 A and 60 V, respectively, when the welding speed was 150 mm/min. In another process, the TIG welding is carried out at a welding speed of 120 mm/min at the same arc voltage and heat input to the material so that weld quality remains the same. The welding current (in A) for this process is ___________ .

[ME 2015,Set-2]

Question 21:In a linear arc welding process, the heat input per unit length is inversely proportional to

[ME 2015,Set-1]

Question 22:In a DC arc welding operation, the voltage-arc length characteristic was obtained as Varc = 20 + 5l where the arc length l was varied between 5 mm and 7 mm. Here Varc denotes the arc voltage in Volts. The arc current was varied from 400 A to 500 A. Assuming linear power source characteristic, the open circuit voltage and the short circuit current for the welding operation are

[ME 2012]

Question 23:Which one among the following welding processes uses non-consumable electrode?

[ME 2011]

Question 24:In arc welding of a butt joint, the welding speed is to be selected such that highest cooling rate is achieved. Melting efficiency and heat transfer efficiency are 0.5 and 0.7, respectively. The area of the weld cross section is 5 mm2 and the unit energy required to melt the metal is 10 J/mm3.If the welding power is 2 kW, the welding speed in mm/s is closest to

[ME 2008]

Question 25: A direct current welding machine with a linear power source characteristic provides open circuit voltage of 80 V and short circuit current of 800 A. During welding with the machine, the measured arc current is 500 A corresponding to an arc length of 5.0 mm and the measured arc current is 460 A corresponding to an arc length of 7.0 mm.
The linear voltage (E) - arc length (L) characteristic of the welding arc can be given as (where E is in Voit and L is in mm)

[ME 2007]

Question 26:In an arc welding process, the voltage and current are 25 V and 300 A respectively. The arc heat transfer efficiency is 0.85 and welding speed is 8 mm/s. The net heat input (in J/mm) is

[ME 2006]

Question 27:Two 1 mm thick steel sheets are to be spot welded at a current of 5000 A. Assuming effective resistance to be 200 micro-ohms and current flow time of 0.2 second, heat generated during the process will be

[ME 2004]

Question 28:Which of the following arc welding processes does not use consumable electrode

[ME 2002]

Question 29:Two plates of the same metal having equal thickness are to be butt welded with electric arc.When the plate thickness changes, welding is achieved by

[ME 2002]

Question 30:Preheating before welding is done to

[ME 1996]

Question 31:The electrodes used in arc welding are coated.This is not expected to

[ME 1994]

Question 32:In DC welding, the straight polarity (electrode negative) results in

[ME 1993]

Question 33:At small variations of arc length at operating conditions, the manual metal arc welding transformer provides nearly

[ME 1990]

Question 34:Penetration is increased by

[ME 1990]

Question 35:Which of the following powders should be fed for effective oxy-fuel cutting of stainless steel.

[PI 2001]

Question 36:During gas welding of copper sheets a neutral flame was used consuming 8 litres of acetylene.But the weld was found to be defective. So it was rewelded using an oxidizing flame. The likely consumption of oxygen in litres will be

[PI 1993]

Question 37:In welding a mild steel sheet using an oxyacetylene flame, the total amount of acetylene consumed was 8.0 litres, the oxygen consumption from the cylinder is

[PI 1989]

Question 38:The temperature of a carburizing flame in gas welding that of a neutral or an oxidizing flame

[ME 2002]

Question 39:For butt welding 40 mm thick steel plates, when the expected quantity of such jobs is 5000 per month over a period of 10 years, choose the best suitable welding process out of the following available alternatives.

[ME 1999]

Question 40:For gas welding a particular job using a neutral oxyacetylene flame the acetylene consumption was 10 litres. The oxygen consumption from the cylinder in liters will be

[ME 1991]

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