K.L.

N COLLEGE OF ENGINEERING
ME8352 MANUFACTURING TECHNOLGY-I
UNIT- 2 Part-A&B (2 Marks with answers and 16 mark ) Anna University questions

1. What are the advantages of welding? (Apr’05)

● Permanent joints can be obtained

● Strength of the join is high when compared to riveted joints

● Uniform distribution of same parent metal at the joint can be ensued.

● Welded parts can be used in heavy duty applications.

2. State any four applications of welding process.

● Fabrication and erection of steel structure in industry.

● Construction of structural joints.

● Aircraft frame works, railway wagons and furniture.

● Automobile bodies and ship building.

3. Differentiate fission welding from fusion welding. [Anna Univ. Nov’10]

In plastic welding, the metals are heated to a plastic state and pressed together to make the joint.
In fusion welding, the literals are heated to a molten state and then it is allowed to solidify (without
application of pressure).

4. What is meant by gas welding?

Gas welding is one type of welding processes in which the edges of the metals to be welded are
melted by using a gas flame.

5. What is the principle of oxy-acetylene gas welding?

In oxy-acetylene gas welding, the edges of the metals to be welded are melted by using the heat
obtained by burning a mixture of oxygen and acetylene gas. The gases are mixed in the required in a
welding torch which provides a control for the welding flame. The flame is produced at the tip of a
welding torch.

6. What are the various gases commonly used in gas welding?

● Acetylene

● Hydrogen

● Propane

● Butane.
7. Mention the types of gas welding process.
● Air-acetylene welding
 ● Oxy-acetylene welding

● Oxy-hydrogen welding.

8. What is the function of welding torch?

The gases are mixed in the required proportion in a welding torch which provides the control
for the welding flame

9. Differentiate between solid state welding and fusion welding.

Solid state welding
● It does not require melting of weld surfaces.

● Dissimilar materials can be easily joined together.

● Process is done by combination of heat and pressure.

Fusion welding
● It requires melting of weld surfaces.

● Dissimilar materials are difficult to join together.

● Process is done by molten pool to add strength to weld joint.

10. Differentiate between brazing and soldering.

Brazing
● It is done at temperature above 450c

● Workpieces are heated.

● May change in mechanical properties of joint.

● Cost and skill requirement are high.

Soldering
● It is done at temperature below 450c

● No workpieces are heated.

● No change in mechanical properties of joint.

● Cost and skill requirement are very low.

11. Principle used in percussion welding.

Fusion is obtained simultaneously over the entire area of the contacting surfaces. The heat that
causes fusion is obtained from an electric arc produced by the rapid discharge of stored energy in
percussion welding.

12. State whether flux is used in aluminum gas welding. Name two chemicals used in flux
manufacture.
 Non-ferrous metals generally require fluxing. The chemicals used to manufacture flux are
borates or boric acid, soda ash & small amounts of other compound such as sodium chloride,
ammonium sulphate and iron oxide.

13. Explain fusion welding.

Fusion welding is a group of process that bond metal together by heating a portion of each
piece above the melting point and causing them to flow together. A filler material is used to insure the
joint filled.

14. Mention the application of friction welding.

● H.S.S. twist drills

● Gas turbine shafts

● Steering columns

● Welding of sinetered products etc.,

15. List out any four arc welding equipment.

⮚ Welding generator(DC) or transformer(AC)

⮚ Electrode and electrode holder

⮚ Two cables and gloves and protective shield.

16. What are the diameter and length of the electrodes available in the market?
⮚ Diameter(mm): 2,2.5,2.15,4.0,5.0,6.3 up to 12

⮚ Length (mm): 200mm to 450mm

17. What is the principle of resistance welding?

In resistance welding, the parts to be jointed are heated to plastic state by their resistance to
the flow of electric current and mechanical pressure is applied to complete the weld.

18. What is the purpose of flux?

● To act as a shield to the weld

● To prevent atmospheric reaction between molten metal and atmosphere.

19. How can slag inclusion in welding be avoided?

● Avoid multilayer welding.

● Reduce arc length.

● Increase electrode angle

● Avoid using large electrode.

20. How does brazing differ from braze welding?
The difference between brazing and welding processes is more sufficient: in the welding
processes edges of the work pieces are either fused (with or without a filler metal) or pressed to each
other without any filler material; brazing joins two parts without melting them but through a fused
filler metal.

21. Why is flux coated on filler rods?

To act as a shield weld and to prevent the atmospheric reaction between molten metal and
atmosphere.

22. What is the role of fluxes in welding? [Anna Univ. Apr’5, Nov’13, Dec’14 & May’16]
Fluxes are used in welding to prevent the atmospheric reaction and remove impurities

23. What are the three types of flame? [Anna Univ. Nov’09]
● Neutral flame

● Oxidising flame

● Carburising flame

24. How can the neutral flame be obtained?

The neutral flame can be obtained by supplying equal quantity of oxygen and acetylene.

25. What are the different cones in carburising flame?

● Sharp inner cone

● White intermediate feather cone

● Bluish outer cone.

26. What are the applications of carburising flame? [Anna Univ. Nov’09]
Carburising flame is used for welding the following metals:
● Very few carbon steel

● Monel alloy

● Alloy steels and

● Non-ferrous metals.

27. How is the oxidizing flame obtained and where it is used?

The oxidizing flame is obtained by supplying excess oxygen than acetylene.
The oxidising flame is mainly used for welding brass and bronze materials.

28. Sketch an oxidizing flame in Oxy acetylene gas welding [Anna Univ. May’17]
29. State the applications of air acetylene welding.
● Lead welding

● Low melting temperature metals and alloys.

30. State any two applications of oxy-hydrogen welding.

● Welding of aluminium.

● Welding of lead and magnesium.

31. Name the types of gas welding techniquies based on flame movement
● leftward or forward welding

● Rightward or backward welding.

32. How does penetration wary for DCSP and DCRP welding? [Anna Univ. Dec’17]
In DCSP the electrode is connected with the –ve terminal of the power sources and base metal
are connected with +ve terminal but in DCRP, the electrode is connected with the +ve terminal of the
power sources and base metal are connected with -ve terminal. Although penetration depends on a
number of factors, DCSP tends to enhance the achievable penetration. Electrons liberated from the
electrodes are accelerated towards base metal due to potential difference between them and finally
strike the base metal surface at a very velocity. Due to striking the kinetic energy of electrons is
converted into thermal energy, Therefore high heat is generated at the base metal surface. So it can be
stated that DCSP provides maximum penetration and DCRP provides minimum penetration

33. What are the advantages of gas welding?

● Temperature of flame can be easily controlled.

● The amount of filler metal deposits can be controlled easily.

● The flame can be used for welding and cutting.

● All types of metal can be welded.

● The cost of equipment is less.

● It can be used in the factory or in the field.

● Maintenance cost of gas welding equipment is less.

34. Mention any two limitations of gas welding.
 ● It is a slow process.

● Handling and storing of gas cylinders need more care

35. State the applications of gas welding.

● Oxyacetylene welding is extensively used for joining thin steel sheets.

● It is also used for welding of dissimilar metals, brazing, braze-welding, silver

36. List out any four arc welding equipment. [Anna Univ. May’06]
● Welding generator (DC) or transformer (A.C)

● Electrode

● Electrode holder

● Two cables one for work and other for electrode

● Gloves

● Protective shield.

37. Note down the purpose of filler rod in welding process.

Filler rod or welding rod used in gas welding is to supply additional metal to make the joints

38. Why is shielding of weld area during welding required? [Anna Univ. Dec’15]
Shielding is used to prevent atmospheric reaction between atmospheres (prevention of oxidation).

39. Define arc length and arc crater.

The distance between tip of the electrode and bottom of the arc crater is known as arc length.
The molten metal is forced out of the pool by the electric arc which forms a small depression in the
parent metal where the molten metal is piled up known as arc crater.

40. What do you understand by DC straight polarity?

During the welding process, the positive terminal of DC power supply is connected to the
workpiece and the negative terminal is connected to the electrode.

41. What are the advantages of AC equipment over DC equipment in arc welding? [Anna
Univ.Nov’10]

AC machine (Transformer) DC machine (Generator)

Efficiency is more (80 to 85%). Efficiency is less (30 to 60%).
Power consumption is less. Power consumption is more.
Cost of equipment is less. Cost of equipment is more.
 Any terminal can be connected Positive terminal is connected to
to work or electrode. work and negative terminal is
connected to electrode.
It is noiseless operation. It is noisy operation.

42. Define the term electrode and mention its major classifications. [Anna Univ.Nov’11]
Electrode is a solid rod in arc welding process to produce electric arc by passing & current
through it and workpiece for melting the surfaces or edges that are joined without applying external
force.
Types of electrode:
Consumable electrodes
(a) Bare electrodes
(b)Lightly coaled electrodes
(c) Heavily coated electrodes.
Non-consumable electrodes.

43. Define bare electrode.

The electrode without coating of flux is called bare electrode.

44. What is the purpose of coating on an arc-welding electrode? [MSU—Apr’97]

1. To increase arc stability.
2. To avoid atmosphere reaction.

45. What are the diameter and length of the electrodes available in the market?[Anna Univ.
Nov’09]
Electrodes are available up to 12 mm diameter and 450 mm long.

46. What are the two main differences of consumable electrode and non-consumable electrode?

Consumable electrode Non-consumable electrode

The electrode is with coating of flux. The electrode is without coating of flux.
The electrode is consumed during welding This type of electrode is used for just producing
process. arc and it will not be consumed.

47. Compare shielded metal arc welding and gas welding.

Arc Welding Gas welding

Heat is produced by electric arc. Heat is produced by the gas flame.
The arc temperature is about 4000°C. The flame temperature is about 3200°C.
Filler rod is used as an electrode. Filler rod is introduced separately.
It is suitable for welding medium and thick It is suitable for welding thin work.
work.
Arc welded joints have very high strength. Gas welded joints do not have much
strength.
Filler metal should be same as or an Filler metal need not be same as the
48. What are the advantages of manual metal arc welding?
● Equipment is self-contained, portable and relatively inexpensive.

● Electrode provides its own flux.

● Most metals and alloys can be welded with MMAW.

● It is a useful process for welding in confined spaces.

49. Why shielding of weld area during welding is required? [Anna Univ. Dec'15J
Shielding is used to prevent atmospheric reaction between molten metal and atmosphere.

50. State the limitations of MMAW.

● It is not recommended for welding metals less than 1.5 mm thick.

● Excessive spatter is produced during welding.

● Frequent stop/starts are required to change electrode.

● The process is discontinuous due to limited length of the electrodes.

51. Note down the applications of MMAW.

● Because of the versatility of the process, simplicity of its equipment and operation, shielded
metal arc welding is one of the world’s most popular welding processes.
● MMAW is often used to weld carbon steel, low and high alloy steel, stainless steel, cast iron and
ductile iron.
● While less popular for nonferrous materials, it can be used for nickel, copper and their alloys.

● In rare cases, it is used for aluminium.

52. What is the purpose of using inert gas in TIG welding?

The inert gas surrounds the arc and protects the weld from atmospheric effects. Hence, defects
free joints are made.

53. Name the various equipment used in TIG welding.

● TIG torch or TIG hand piece

● Power transformer

● Shielding gas cylinder

● Pressure regulator and flow meter

● Work clamp

● Coolant system (optional).

54. Mention the various functions of the TIG torch.
● It holds the electrode tungsten.

● It delivers welding current to the tungsten via a welding power cable.

● It delivers shielding gas to TIG torch nozzle. The nozzle then directs the shielding gas to cover
the weld pool protecting it tom contamination from the surrounding air.
● It often will be the way of getting the welder control circuit to the operation, for example: On /
Off power supply and / or amperage control.

55. What arc the advantages of TIG welding?

● It is applicable to wide range of materials such as aluminum, stainless steel, manganese and
copper alloys,
● It is more suitable for thin sections.

● It does not create as much spatter and spark.

● It creates a better work environment with less smoke and fumes.

56. State any two limitations of TIG welding.

● It is generally restricted for flat and horizontal welding.

● Discontinuities in the weld are due to contamination of the tungsten electrode by the molten
metal.
● It is slow in operation than consumable electrode gas-metal arc welding.

● It emits brighter UV rays when compared to other welding processes.

57. Mention the applications of TIG welding.

● Aluminium, magnesium, copper alloys can be welded easily. Inconel, carbon steels and
stainless steels can be welded.
● Can sealing, instrument diaphragms and transistor cases can be welded very efficiently.

● Expansion bellows and other delicate parts can be joined.

● Atomic energy', aircraft, chemical and instrument industries use this welding process.

● A rocket motor chamber fabrication welding can be done by

58. What does MIG welding mean?

Metal inert gas welding is 'referred as MIG welding. It is also called Gas Metal Arc If welding
(GMAW). In this arc welding, the electric arc is produced between a consumable metal wire electrode
and the workpiece.
59. What are the gases common ly used in MIG welding?
● Argon

● Carbon dioxide

● Helium.

60. Distinguish MIG welding and TIG welding. [Anna Univ. May'06J

MIG Welding TIG Welding

It uses consumable electrodes. It uses non-consumable electrodes.
It is used for thicker material. It is used for thinner material.
Feeding of; electrode is continuous. Feeding of electrode is discontinuous.
It produces low quality weld. It produces high quality weld.
It needls, less skilled welder. It needs more skilled welder.
Automation is easy. Automation is difficult.
It produces more spark, smoke and
It produces less spark, smoke and spatter.
spatter.

61. List down the advantages of MIG welding.

● It is more suitable for welding a variety of ferrous and non-ferrous metals

● No flux is required and hence, there is no slag to remove.

● Multiple pass welding does not require any intermediate cleaning of weld pool.

● Because of the relatively simple process, training the operators is easy.

● This process is rapid, versatile and economical.

62. What are the limitations of MIG wedding?

● It cannot be used in the vertical or overhead welding positions due to the high heat input and
the fluidity of the weld puddle.
● The process is more expensive than any other types of welding.

● Outdoor welding is not easy because of effect of wind and dispersing the shielding gas

● The equipment is complex compared to equipment used for the shielded metal-arc welding
process.

63. State the applications of MIG welding.

● Since temperatures are relatively low, it is suitable for thin sheet section (less than 6 mm).
Examples: Motorcar manufacture, shipbuilding, aircraft engineering, heavy electrical
engineering and the manufacture of tanks, pressure vessels and pipes.
 ● It is also used in fabrication and manufacturing industries.

● The most common application of MIG welding is automotive repair and such repairs can be
carried out on a number of different vehicles whether they are large, small, light or heavy.
● MIG welding can be used to establish hard facing or it can even be used to reinforce the surface
of a worn out railroad track.

64. State any two limitations of submerged arc welding.

● It is not suitable for welding works which is inclined and vertical.

● The welding zone is not seen. So, it is difficult to guide the electrode movement.

● Operation is limited to some specific metals.

● The application is limited to straight scams and pipes and vessels.

65. Name the different areas in which submerged arc welding is used.
● Construction Industry

● Automotive industry

● Manufacturing Industry

● Shipping Industry,

66. What is the principle of resistance welding? [Anna univ. Apr'05, May’06 & Nov'09]
Resistance welding processes are pressure welding processes in which heavy current is
passed for short time through the area of interface of metal to be joined with the application of
pressure.

67. Classify resistance welding.

Spot welding, Seam welding, Projection welding, Resistance butt welding, Flash butt welding,
Percussion welding

68. What are the features of resistance welding?

● No flux such as solder is necessary. So, welded parts can be easily recycled.

● Easy operation as only pressing buttons facilitates process automation and it does not
require trained skills unlike arc welding and gas welding.
● As this welding is performed efficiently in a short period of time, it is suited for a high-
volume production of low-cost products.
● Since welding is done in short time duration, it gives less heat-affected area on workpieces
by resulting a beautiful appearance with less indentation.
 ● Electric facility is required in some cases due to use of large current. Optimum welding
parameters must be figured out before actual welding since those parameters depend on
material and thickness of parts to be welded. Welding condition setting must be prepared.

69. State the functions of electrode in resistance welding.

● Electrodes keep the parts aligned and in place.

● They are used to apply the required pressure to develop the correct surface resistance at the
interface for containing the molten metal to avoid weld expulsion and forge the nugget near
the end of the cycle.
● They convey the electric welding current to the electrodes.

● They also dissipate excess heat to avoid the surface melting.

70. Mention the advantages of resistance welding.

● Less skill is required to operate the resistance welding machine.

● This type of welding is well suited for mass production as it gives a high production rate.

● There is no need of using consumables such as brazing materials, solder or welding rods in
this process except electrical power and a relatively smaller electrode wear.
● Heating the workpiece is confined to a very small part which results less distortion.

● It is possible to weld dissimilar metals as well as metal plates of different thickness.

71. State the limitations of resistance welding.

● Certain resistance welding processes are limited only to lap joints.

● Spot welds have low tensile and fatigue strength.

● Equipment is not portable as it is heavy.

● The cost of equipment is high.

72. What are the applications of resistance welding?

● Resistance welding is used in mass production for welding sheet metal, wire and tubes.

● It is used in welding bars, boxes, cans, rods pipes and frames metals of medium and high
resistance materials such as steel, stainless steel, monel metal and silicon bronze which are
easy to weld.
 ● It is used in welding aircraft and automobile parts.

● It is used for making cutting tools.

● It is used for making fuel tanks of cars, tractors etc.

● It is used for making wire fabrics, grids, grills, mesh weld, containers etc.

73. What is the minimum distance maintained between two successive spot welds made by
resistance welding? Why? [Anna Univ. Apr’I3]
The minimum distance of 150 mm and maximum distance of 300 mm between two
successive spot welds or the acceptable distance of 16 times of thickness of metal to be welded
because the shunt current flowing through already formed weld spot reduces the efficiency of the
welding process.
74. What is meant by nuggets in electrical resistance welding? [Anna Univ. Dec’14]
The point at which the molten metal is created between for short period of time due to
maximum heat generation is called nugget.
75. Why is spot welding commonly used in automotive bodies in large appliances?
[Anna Univ. May'I6]
Many parts of the car are made up of sheet metals such as frame, the bodv. the suspension,
etc. So, the most common application of spot welding is in the automobile manufacturing industry
where it is used almost universally to weld the sheet metal to form a car. Also, the use of spot
welding in the auto industry is mainly to the stamping of sheet structure of the body panels in its lap
to make the weld pieces together as one.

76. Write down the advantages of spot resistance welding.

● Spot welding is quick and easy.

● There is no need to use any fluxes or filler metal to create a join by spot welding and there is no
dangerous open flame.
● Spot welding can be performed without any special skill.

● The rate of production is high.

77. State the limitations of spot resistance welding.

● It can create only localized joints which may not be particularly strong.

● To achieve small cost of building, the weld manufacture cost is not very high.

● The electrodes have to be able to reach both sides of the pieces of metal that are being joined
together.
 ● Warping and a loss of fatigue strength can occur around the point where the metal has been
spot welded.

78. Mention the various applications of spot resistance welding.

● It is used in joining killed carbon steel, low alloy steel, high alloy steel & titanium.

● It is used in manufacture of sheet metal goods.

● It is used in assembling sheet metal to steel structures.

● It is used in making cookware and muffler.

79. What is seam welding?

In spot welding, if both bottom and top electrodes are replaced by rotating wheels, it is called
seam welding.

80. How is the seam welding used as an application of spot welding? [Anna Univ. Dec’15]
The metal to be welded is moved between electrodes and electric pulses create spots of molten
metal that overlap to form the continuous seam.

81. Classify seam welding.

● Conventional resistance seam-welding

● Overlapping spot in a seam weld

● Roll spot welds

● Mash-seam welding.

82. Mention any two advantages and limitations of seam resistance welding.
Advantages:
● The production of single seam weld and parallel seams can be got simultaneously.

● Filler materials are not required and hence, there is no associated gases and fumes.
Limitations:
● The welding process is restricted to a straight line or uniformly curved line.

● The metals sheets having thickness more than 3 mm can cause problems while welding.
83. State any two applications of seam welding.
● It is used to make tin cans, leak proof tanks, automobile mufflers, gasoline tanks, drums,
radiators, household utensils, transformers, refrigerators, evaporators and condensers,
automobile bodies etc. It is also used for welding thin sheets.
 ● Circumference weld is possible in rectangular or square or even in circular shapes.

84. What do you understand by projection welding?

Projection welding is an electric resistance welding process that uses small projections,
embossments or intersections on one or both components of the weld to localize the heat and
pressure.

85.Mention any two advantages and applications of projection welding.

Advantages:
It can weld metals of thickness which is not suitable for spot welding.
Projection welding electrodes have a longer life when compared to spot welding electrodes because
these electrodes have to withstand less wear and less heating.
Applications:
It is used to make press-tools.
This process is more suitable for cross welding of a number of wires or rods which are commonly
used to make wire fencing, shopping carts and stove grills.

86. What are the types of resistance butt welding?

● Upset butt welding

● Flash butt welding.

87. Write down the advantages and applications of resistance butt welding.
Advantages:
● Upset butt-welding is more suitable for welding many alloys which are difficult to weld using
fusion welding.
● The metal retains base metal characteristics because the base metal does not melt during
welding.
Applications:
● This process is mainly used for welding nonferrous materials of smaller cross section such as
bars, rods, wares, tubes etc.
● Upset welding is used to make closure of capsules, small vessels and containers.

88. What is meant by flash butt welding?

The welding process in which the ends of rods are heated and fused by an arc struck
between them and forged to produce a weld is called flash butt welding.

89. Differentiate between upset butt welding and flash butt welding.
 Upset butt welding Flash butt welding
The weld is completed by contacting two ends The weld is completed by contacting two ends
of the workpiece which are rotated with very of the workpieces which are rotated with very
high rpm and by contacting suddenly. high rpm and when the contact is just made
flash will occur. This flash is used to melt the
portion to be welded
90. State the advantages and applications of flash butt welding.
Advantages:
● Many dissimilar metals with different melting temperature can be flash welded.

● Flash butt welding allows fast joining of large and complex parts.

● Power consumption is less.

● Clean welds can be made.

Applications:
● Butt welding is used in welding automobile components such as body, axles, wheels and frames.

● It is also used in welding motor frames, transformers tanks and many types of sheet steel
containers such as barrels and floats.

91. Write down the applications of percussion welding.

● It is used for fine wire leads to filaments such as in lamps and electrical components.

● The method is also used to weld pins, studs, bolts and soon.

92. What do you infer about stud welding?

It is one kind of resistance welding process. An electric arc is produced between stud and flat
surface of the workpiece. The arc melts the end of the stud and the pressure is applied on the stud
to fix it on the work metal surface.

93. Mention any two advantages and applications of stud welding.

Advantages:
● Deep weld penetration is possible.

● High speed welding of studs on thin steel sheets is possible.

Applications:
● In the automotive industry, the process is used to assemble heat shields, power steering and
dashboard components, instrument panels, insulation, exhaust systems, lighting systems,
brake lines, trim and electrical wire routing.
 ● In the farm equipment industry, it is used to assemble fenders, brackets, cabs, spreaders,
shrouding, thresher teeth, wiring and hose management parts. It is also used in lawn and
garden equipment such as tractors, mowers and seeders.
● In the commercial appliance industry, it is used in commercial dishwashers, bottle washers,
cooking equipment and griddle plate assemblies.

94. State the advantages and applications of low-frequency electric resistance welding.
Advantages:
● The low frequency process produces high quality weld.

● It is more prone to selective seam corrosion, hook cracks and inadequate bonding of seams.
Limitations:
● It is no longer used to manufacture pipe.

● The high frequency process is still being used to manufacture pipe for the use in new
pipeline construction.

95. What are the two types of plasma arc welding? [Anna Univ.May’17]
● Non-transformed arc

● Transferred arc.

96. Write short notes on transferred and non-transferred in plasma arc welding.[Anna Univ. Apr’13]
● Transferred type:
In transferred type, the tungsten electrode is connected to negative terminal and the workpiece is
connected to positive terminal. An electric arc is maintained between electrode and workpiece
which heats a co-axial flowing gas and maintains it in a plasma state. It is difficult to initiate the arc
first between workpiece and electrode. So, the pilot arc is struck between nozzle and electrode.
● Non-transferred type:
In this type, power is directly connected with the electrode and torch of nozzle. The electrode
carries the same current. Thus, the ionizing is qt high velocity gas that is strewing towards the
workpiece. The main advantage of this type is that the spot moves inside the wall and heat the
incoming gas and outer layer remains cool. This type plasma has low thermal efficiency

97. Why the temperature in plasma arc welding is much higher than in other arc welding
processes? [Anna Univ. Dec’16]
The plasma arc is constricted with the help of a water-cooled small diameter nozzle which
squeezes the arc, increases its pressure, temperature and heat intensely. It also improves arc
stability, arc shape and heat transfer characteristics.

98. Give some metals and alloy melted by plasma Arc welding process.
Titanium alloys, stainless steels, aluminium alloys and copper alloys.

97. What are the advantages of plasma arc welding?

● Penetration is uniform.

● It has deeper penetration capabilities and produces a narrower weld.

● Arc stability is good.

● Fully penetrated keyholes can be obtained.

98. State the limitations of plasma arc welding.

● Cost of the equipment is expensive.

● Ultraviolet radiations can affect human body.

● More skilled operator is needed than GTAW process.

● The torch is more delicate and complex than a gas tungsten arc torch.

● Gas consumption is high.

99. Mention the applications of plasma arc welding.

● It is used in aerospace applications.

● It is used for melting high melting point metals.

● It is used for welding titanium plates.

● It is used in welding nickel alloys.

● It is used for tube mill applications.

100. State the principle involved in Electro slag welding.

In this welding process, the heat is generated by an electric current passing between
consumable electrode (filler metal) and workpiece through a molten slag covering the weld surface.
In this process, the coalescence is formed by molten slag and the molten metal pool remains shielded
by molten slag.

101. List any four advantages of electro slag welding.

● It can weld materials of thickness up to 400 mm.

● Heavy thickness metals can economically be welded.

 ● Stress formation is low.

● Preparation of joints is easier.

● Slag consumption is low.

102. What are the limitations of electroslag welding?

● It is difficult to weld cylindrical objects.

● Hot cracking may occur.

● Toughness of the weld is low.

● Only vertical position is possible.

● The cost is high as the equipment is fully automatic and it is of special design.

103. State the applications of electro slag welding.

● It is used mainly to join low carbon steel plates and sections are very thick.

● It is used for welding thick sections of alloys steels and nickel alloys.

● This process is used for large structural-steel sections such as heavy' machinery, bridges, ships
and nuclear-reactor vessels.
● Forgings and castings are welded.

104. What is the principle of Thermit welding? [Anna Univ. Nov’12 & Nov’13]
Thermit welding is a welding process utilizing heat generated by exothermic chemical reaction
between components of the Thermit. Thermit consists of one part of aluminium and three parts of
iron oxide. The molten metal produced by the reaction acts as a filler material and joins the
workpieces after solidification. The welding principle is the heat of the Thermit reaction used for
welding in plastic state and mechanical pressure is applied for the joint.

105. What are the advantages of Thermit welding?

● No external power source is required (Heat of chemical reaction is utilized).

● Very large heavy section parts may be joined.

● The process uses simple and inexpensive equipment.

● The process is more suitable particularly in remote locations where the sophisticated welding
equipment and power supply cannot be arranged.

106. State the limitations of Thermit welding process.

● Only ferrous (steel, chromium, nickel) parts may be welded.

● High skill operators are required.

 ● Welding rate is slow.

● Deposition rate is low.

107. Write down the applications of Thermit welding process.

1. Thermit welding process is used for welding damaged wobblers and large broken crankshafts.
2. It is used to restore the broken teeth on gears.
3. Joints in pipes, rails, shafts are made in this process.
4. It is used in welding and repairs of large forgings, and broken castings.

108. Define electron beam welding?

Electron Beam Welding (EBW) is a fusion welding process in which a beam of high velocity
electrons is used for producing high temperatures and melting the workpiece to be welded. The
electrons strike the workpiece and their kinetic energy is converged into thermal energy' by releasing
heat which is used to heat the metal so that the edges of workpiece are fused and joined together
forming a weld.
109. Write down the advantages of EBW.

● High quality weld is produced.

● Deep welding is possible.

● Clean and bright weld can be obtained.

● High speed operation can be achieved.

110. Mention the limitations of EBW.

● The welding cost is high.

● Skilled persons are required.

● It is limited to small size welding.

● Welding should be carried out in vacuum seal only.

111. What are the commercial applications of EBW process?

● Dissimilar metals can be welded.

● Refractory and reaching metals can be welded.

● It is used in aircrafts, missile, nuclear component, gears and shafts.

● It is used in cams.
112. What is meant by laser beam welding?
Laser beam welding (LBW) is a welding process which produces coalescence of materials
 with the heat obtained from the application of a concentrated coherent light beam impinging
upon the surfaces to be joined.
113. List down the types of laser forms.
● Liquid laser

● Gas laser

● Carbon dioxide laser

● Solid-state laser

● Ruby laser

● Semi-conductor laser.

114. Classify laser beam welding.

● Pulsed laser beam welding

● Continuous wave laser beam welding

115. Write down the applications of laser beam welding.

● Thin metals about 0.5 mm to 1.5 mm thick can be welded. It includes welding of foils, stents,
sensor diaphragms and surgical instruments.
● It can joint dissimilar metals such as copper, nickel, chromium, stainless steel, titanium and
columbium.
● It is very much useful in electronic components welding.

● It is used in aircraft components joining.

116. Wit at do you infer about friction welding?

Friction welding is a solid state welding process in which coalescence is achieved by frictional
heat combined with pressure.

117. Write down the sequence in friction welding.

The sequence of operation in the friction welding process is as follows:
Step 1: Component fitted to rotating chuck is rotated at high speed.
Step 2: Component fitted to stationary chuck is brought into contact under axial force. Step 3: As axial
force is increased, the flash begins to form.
Step 4: Component fitted to rotating chuck comes to stop as the weld is completed.

118. Classify friction welding.

● Continuous-drive or spin friction welding

● Inertia friction welding

 ● Linear friction welding.

119. Note down the advantages of friction welding.

● Power consumption is low.

● The operation is easy and it uses simple equipment.

● Parameters are easily determined.

● Less time is required.

● It is smooth and clean process.

120. Differentiate between friction welding and inertia welding.

Friction welding Inertia welding
Power flows from electric motor. Power flows from flywheel.
Size of the motor limits the power. Power is independent of the size of the motor.
Heat is produced by sliding motion. Heat is produced by intermolecular bonding.
Friction speed is very important. Speed of the flywheel is very important.

121. Mention the limitations of friction welding.

● It is used only for joining small parts. Heavy components are not possible to weld.

● There is a possibility of heavy flash out.

● Heavy rigid machines are required due to high thrust pressure.

● Process is restricted to flat and angular butt welds.

122. State the applications of friction welding. [Anna Univ. Nov’10]

● Because of high quality of the weld obtained, the process is widely accepted in aerospace and
automobile industry for critical parts.
● In aerospace industry, turbine blade joining, seamless joining etc. are produced using friction
welding.
● In automobile industry, bimetallic engine valve, axle shafts, universal joint yoke, gear hub etc.
are produced using friction welding.
● In consumer goods manufacturing, it is used for producing hand tools, sports equipment.

123. What is friction stir welding?

Friction Stir Welding (FSW) is a solid state welding process in which a rotating tool is fed along
the joint line between two workpieces. It is used to join two facing surfaces.

124. Mention the advantages of friction stir welding.

 ● Improved safety is obtained due to the absence of toxic fumes or the spatter of molten
material.
● There is no use of consumables.

● It can be easily automated on simple milling machines due to low setup cost and less training.

125. State the limitations of friction stir welding.

● An exit hole remains the same after the tool is withdrawn from the work.

● Large down forces are required with heavy-duty clamping necessary to hold the plates
together.
● It produces slower traverse rate than some fusion welding techniques although this may be
offset if fewer welding passes are required.
● Process is restricted to flat and angular butt welds.

126. What are the applications of friction stir welding?

Friction stir welding processes are mainly used in the following industries:
● Automobile: Bimetallic engine valve, universal joint yoke, gear hub etc.

● Aerospace: Turbine blade joining, seamless joining etc.

● Consumer: Hand tools and sports equipment.

● Industrial machines: Spindles, tapers and tools.

127. What is diffusion welding?

Diffusion welding is a solid state joining process in which the strength of the joint results
primarily from diffusion.

126. Write down the stages involved in diffusion welding.

Stage 1. Deformation and interfacial boundary formation.
Stage 2: Grain boundary migration and pore elimination.
Stage 3: Volume diffusion pore elimination.

127. What are the advantages of diffusion welding? '

● Plastic deformation at surface is minimal.
● There is no limitation in the thickness of workpieces.

● The bonded surface has the same physical and mechanical properties as the base material.

● The diffusion bonding is able to help us to build high precision components with complex
shapes. Also, the diffusion is flexible.

128.Mention the limitations of diffusion welding.

 ● It is a time consuming process due to low productivity.

● Very thorough surface preparation is required prior to welding process.

● The mating surfaces must be precisely fitted to each other. *

● It is relatively high initial investments in equipment.

129. List down the applications of diffusion welding.

● It is used in joining of high-strength and refractory metals based on titanium in aerospace and
nuclear industries.
● Diffusion welding is usually used on sheet metal structures such as nuclear and electronics
industries.

130. What is ‘brazing’? [Anna Univ. Nov’11J

The process of joining two metals by using filler metal is known as brazing. The filler metal
having liquid temperature is above 427°C.

131. What are the functions of flux in welding electrode? [Anna Univ. Apr’11]
● To act as a shield to the weld

● To prevent atmospheric reaction between molten metal and atmosphere (prevention of

oxidation).

132. Define soldering.

The process of joining two metals by using filler metal is known as soldering. The filler metal
having liquid below is 427°C.

133. Why is flux used in soldering and brazing?

The main use of flux in the brazing is to the filler metal.

134. Give some fluxes used in brazing.

● Fluorides

● Chlorides

● Borates.

135. Classify brazing methods.

● Torch brazing

● Furnace brazing

● Induction brazing

● Dip brazing
 ● Resistance brazing

● Laser and electron beam brazing.

136. What are the commonly used fluxes and solders in soldering?
● Fluxes: Ammonium oxide and Zinc Chloride

● Solders: Tin alloy, lead alloy

137.What are the soldering methods?

● Hard soldering

● Soft soldering

● Dip soldering

● Wave soldering.

138. What is a soldering flux?

A substance added to molten metals on the surfaces to clean the surfaces and result in a better
bond is called soldering flux.

139. Write the difference between brazing and soldering. [Anna Univ. May’15]
Soldering Brazing
The filler material used in this process is The filler material used in this. process is called
ferrous, copper or silver based materials. solder.
Filler material has the melting point below Filler material has the melting point above 450°C.
450°C.
Temperature involved in this process is low. Temperature involved in this process is high.
The joints are the weakest joints. Joints are stronger.
Dismantling of joints is not possible. Dismantling of joints is possible.

140. Name the various causes for the defect porosity in welding. [Anna Univ. May ’15]
Porosity is caused by improper gas shielding, moisture in the electrode, incorrect welding
technique, improper cleaning of weld surface, sulfur in weld metal or surface contaminants. They
occur mainly due to entrapped gases. Presence of gases such as oxygen, nitrogen and hydrogen in the
solidifying metal produces porosity.

141. How arc the welding defects identified? [Anna Univ. May ’06]
Welding defects are identified by conducting various non-destructive testing,

142. List down the major defects in welded joints.

● Lack of fusion

● Lack of root penetration

● Cracks
 ● Porosity

● Undercut

● Distortion

● Slag inclusion

● Lamellar tearing

● Deformation

● Overlapping.

143. Define the terms weld decay and dilution. [Anna Univ. Dec’17]
Weld decay is form of intergranular corrosion usually of stainless steels or certain nickel base
alloy which occurs in the heat affected zone during the welding operation due to sensitization
Weld dilution is defined as the weight of the base metal melted divided by the total weight of
the weld metal. For example for dilution of 0.40 the fraction of the weld metal obtained from the
consumable electrode is 0.60.

144. Define undercut in welded joints.

Undercut is a groove gets formed in the parent metal along the sides of the weld.

145. Mention the reasons of occurring distortion after carrying out welding in metal joining
process.
● Insufficient clamping of workpieces

● Many number of passes

● Stresses in plates

● Unsuitable welding sequence.

146. What is meant by overlap?

Overlap is the protrusion of the weld metal beyond the weld toe or weld root. It may occur
because of fusion problem.

147. What are the steps used in testing the welded joint using magnetic particle test?
● The surface of the specimen is roughly cleaned wiping with a piece of textile.

● The fluorescent magnetic spray is applied on the surface being inspected.

● Magnetic field Is applied with a strong magnet to the location of interest. The iron powder is
attracted to the crack and the iron powder will be gathered near the cracks.
● The spots where the fluorescent magnetic particles accumulated is inspected under UV light.

148. Why do residual stresses get developed in weldments? [Anna Univ. Dec’16]
Residual stresses in welded joints are primarily developed due to differential weld thermal cycle
(heating, peak temperature and cooling at the any moment during welding) experienced by the weld
metal and region closed to fusion boundary i.e. heat affected zone.

Part-B

1. Explain the process of metal transfer in GMAW process with neat sketch. Also explain the
relationship between the shielding gas used and the type of metal transfer in GMAW.
2. Discuss the various types of resistance welding operations. Can dissimilar metals be welded
by resistance welding.
3. Explain the process of resistnce spot welding with one complete welding cycle.
4. Explain the process of transfer arc and non-transfer arc mode of operation in plasma arc
welding with applications.
5. Name any four welding process used for welding of copper. Explain any process in detail.
6. Compare the process of soldering and brazing.
7. List out the different types of welding process. Briefly explain the working principle of any
two welding process.
8. What is meant by welding defect? Explain any five welding defects.
9. Discuss the filter and flux materials using in Arc welding process.
10. Describe the types of flames obtained in an oxy-acetylene gas welding process giving the
applications.
11. Explain the TIG and MIG system of welding , Give the application of each.
12. Explain the resistance welding process giving the equipment, parameters controlled and
the applications.
13. With a neat sketch, explain the process of submerged arc welding.
14. Explain the merits, limitations and applications of Electron beam welding.
15. Explain the features of neutral, reducing and oxidizing flames . Why is a reducing flame so
called?
16. Illustrate the thermit welding process with neat sketch land also state its applications.
17. Compare the Laser Beam Welding with Electron Beam Welding.
 18. Describe with a neat sketch the components of Oxyacetylene gas welding equipment.
19. Discuss principle of adhesive bonding. List out any four types of adhesives.
20. Describe with neat sketches various steps in friction welding
21. Describe with a neat sketch the principle of percussion welding. State its advantages and
limitations.

Anna University questions - Part-B

1. What are the advantages and disadvantages of welding compared to other types of
assembly operations? [Anna Univ. May'16]
2. List out the different types of welding process. Briefly explain the working principle of
any two welding process.[Anna Univ.Nov’10]
3.Describe with a neat sketch the components of oxyacetylene gas welding equipment.
[Anna Univ. Apr’10, Nov’12 & Dec’14]
4. Explain the equipment of an Oxy-Acetylene gas welding . .[Anna Univ.Nov’15]
5. Sketch the three types of flame in Oxy-Acetylene gas welding and state their characteristic [Anna
Univ. May ’06 ,Nov ’ll]
6. Describe the types of flames using in gas welding .[Anna Univ.Nov’09]
7. Explain the metal arc welding process with a neat sketch. [Anna Univ. Nov '12 &. May’I5]
8. Discuss the various filler and flux materials used in welding. [Anna Univ.Nov'09]
9. Distinguish between gas welding and arc welding. [Anna Univ. Apr’05]
10. Explain about the equipment and operation of GTAW process. [Anna Univ. Nov ’09 & Dec'15]
11. Describe MIG welding with a neat sketch.[Anna Univ. May’06]
12. Explain the gas metal arc welding processes with neat sketch and its process capabilities. [Anna
Univ. Nov’13 & May’16]
13. With the help of suitable diagrams, explain the following types of welding: [Anna Univ. Apr’12]
(i) TIG welding process.
(ii) Electro slag welding process.
14. Compare MIG and TIG welding in respect of their principle of working and field of
application. [Anna Univ. Dec’16]
15. Sketch the overall set up of submerged welding process and explain the working principle.
Mention its applications. [Anna Univ. May’06, Nov’10, Apr’13 & May’15]
16. Differentiate electro gas welding and electro slag welding with its principles and
applications. [Anna Univ. Nov ’13 & Dec '14]
17. What is the principle of resistance welding processes? [Anna Univ. May’16]
18. Explain the resistance welding process giving the equipment, parameters controlled and the
applications. [Anna Univ. Dec’09]
19. Explain the resistance spot welding process with a neat sketch [Anna Univ. Apr'06 & Dec'15]
20. Explain the percussion welding process. [Anna Univ. May’05]
21. Describe with a neat sketch the principle percussion welding process. State its advantages and
limitations. [Anna Univ. May’10]
22. Describe plasma arc welding and give their applications.[Anna Univ. May '06, Nov'11,12]
23. What is the principle of Thermit welding? Explain with a neat sketch of the welding
arrangement. [Anna Univ. Apr’12]
24. Explain the variants of Thermit welding process. [Anna Univ. Dec ’15]
25. Explain the method of electron beam welding and given their applications.
26. Explain the electron beam welding process with a neat sketch.[Anna Univ. May '06 & Nov '10]
27. Explain the principle of operation, advantages and limitations of electron beam welding.
[Anna Univ. May '06, Apr'12 & Dec' 14]
28. Explain the method of laser beam welding and give their applications.
29. Explain the process of rotary drive friction welding with its advantages and limitations.
[Anna Univ. Dec '14]
30. Explain die three variables involved in continuous drive friction welding.[Anna Univ: Apr 75]
31. Describe with neat sketches various steps in friction welding. [Anna Univ. Apr'10]
32. Write short notes on (i) Electron beam welding (ii) Friction stir welding.[Anna Univ. Dec'16]
33. Describe the ultrasonic welding process with a neat diagram. [Anna Univ. MaryU5]
34.Explain the following welding process with neat sketch [Anna Univ. Nov’13]
(i) Resistance seam welding
(ii) Friction stir welding.
35. Explain the various welding positions with a neat sketch. [Anna Univ. May ’IS]
36. Describe brazing process.
37. Explain various methods of brazing.
38. Write short notes on soldering process.
39. What is a soldering flux? What are the different types of soldering fluxes used?[Anna Univ. Dec 16]
40. Distinguish between soldering and brazing. [Anna Univ. May ‘06]
41. Describe filler and flux materials used in brazing and soldering processes.
42. What is meant by welding defect? Explain any five welding defects. [Anna Univ. May ‘10]
43. Sketch the different types of weld defects and mention how they occur. [Anna Univ. Nov 10, 12]
44. What are the non-destructive tests used in welding inspection? Explain any one method. [Anna Univ
. Apr ‘13]