Resistance Welding?

Resistance Welding can be defined as; it is a fluid state welding technique

where the metal-to-metal joint can be shaped inside a fluid state in any case
molten state. Here intensity can be produced at the It is a thermo-electric
cycle in which intensity is created at the edge planes of welding plates as a
result of electric resistance and a weld joint can be made by applying low-
strain to these plates. This type of welding utilizes electric resistance from
produce heat. Despite its high efficiency and pollution-free nature, this
method has few applications due to limitations in material thickness and
equipment costs.

Electric-Resistance-Welding
Working Principle of Resistance Welding
The cycle begins with the metal parts being carried into contact with one
another, sandwiched between two electrode tips. These electrodes are
responsible for applying the requisite pressure to ensure optimal contact
and to firmly hold the parts intact during welding.
When the components are set up, an electric current is brought into the
workpieces by energizing the electrodes. This current flow through the
workpieces, experiencing resistance at the connection point where they
meet.
As the current encounters this resistance, it delivers a lot of intensity at a
sped up pace. The Joule heating effect is a way electrical energy is
effectively turned into intense heat. The intensity created by the resistance
causes the metal at the contact point to rapidly soften and eventually melt.
This heat generation happens due to the energy change from electric to
thermal. The resistance welding equation for heat generation is
H = I 2 RT
Where,
I = Current flowing through the electrodes,
R = is the contact resistance of the point of interaction, and
t = is the time at which the current flows
Types of Resistance Welding
Different types of resistance welding are discussed below.
 Spot Welding
 Seam Welding
 Projection Welding
 Flash Butt Welding
Spot Welding
The simplest form of welding is spot welding, in which the workpieces are
held together by the anvil face’s force. The copper (Cu) terminals will
connect with the work segment and the progression of current through it.
The work portion material applies a couple of protections inside current
stream which will cause restricted heat creation. The opposition is high at
the edge surfaces on account of the air gap. The current starts to supply
through it, then, at that point, it will decrease the edge surface.
 Spot-Welding

The current supply and the time should be enough for the right dissolving
of edge faces. Presently the progression of current will be halted anyway
the power applied with terminal went on briefly, while the weld immediately
cooled. However, the terminals take out as well as reach out to new detect
to make a round piece. The piece size predominantly depends upon
electrode size (4-7 mm).
Advantages of Spot Welding
 Spot welding has high similarity with effectiveness and consistency.
 Spot welding is economical.
 Spot welding gives a significantly more efficient approach to using
electrical energy for welding process.
 Spot welding is a quick welding process.
Disadvantages of Spot Welding
 Spot welding requires an large working area.
 Spot welding uses a heavy welding gun that requires a lot of strength
to operate. Subsequently, spot welding might be extremely hazardous
to the matured welders.
 The thicker materials are not suitable for spot welding.
Applications of Spot Welding
 Spot welding is utilized in different ventures, for example, auto,
aviation, metal furnishings, hardware, building development, and so on.
 Spot welding is utilized in high volume creation applications.
 It is used to weld thin sheets together.
 Spot welding is likewise utilized for manufacturing a wide range of
sheet metal designs where high mechanical strength is required.
 Spot welding can likewise be applied to a wide range of boxes, centers
and encasing cases, and so on.
Seam Welding
This type of welding is also called continuous spot welding where a roller
form electrode can be used to supply current all through work parts. At first,
the roller electrodes are getting out to the work part. These electrode rollers
can carry a high current, melting the edge surfaces and shaping a weld
joint.

Seam Welding

The electrode rollers will start moving on work plates to make a super
durable weld joint. The weld timing and cathode development can be
controlled to ensure that the weld cross-over and work part doesn’t get
excessively warm. When seam welding is used to create airtight joints, the
speed of the welding can be about 60 inches per minute.
Advantages of Seam Welding
 The welds created by the seam welding are impenetrable and water-
tight.
 Seam welding is a quick welding interaction and it tends to be
computerized utilizing mechanical machines.
 It does not require any filler or flux materials.
Disadvantages of Seam Welding
 The resistance seam welding process has a few drawbacks, including
the fact that it uses roller electrodes and can only produce welds in
straight lines or uniformly curved lines.
 It isn’t appropriate for metal sheets of thickness more than 3 mm per
sheet.
Applications of Seam Welding
 Resistance seam welding is utilized for a number of purposes,
including the creation of lap joints.
 It is utilized in assembling cycle of different kinds of strain tight or
sealed tanks, for example, gas tanks, oil switches, transformer tanks,
airplane tanks, and so on.
 Utilized for welding parts of vessels that should to be air tight and water
tight.
 For welding of pipes and tubes.
Projection Welding
Projection welding is like spot welding separated from a dimple can be
generated on work parts at the spot any place weld is liked. At present the
work parts held among cathode as well as a gigantic amount of current
course through it. A little amount of strain can be applied all through the
cathode on welding safeguards. The progression of current all through
dimple which disintegrate it and the power reasons the dimple level and
shape a weld.

Projection-welding

Advantages of Projection Welding

 There is no limitation on the metal thickness, i.e., metal of any
thickness can be welded with the projection welding.
 Multiple welds can be made at once with projection welding.
Subsequently, more result is acquired.
 In the projection welding, less current is gone through the terminals
and low strain is applied. Hence, the anode life is expanded.
 Projection welding gives great intensity balance while welding process.
 The projection welding method results in a weld with a polished
appearance.
Disadvantages of Projection Welding
 The course of projection development is complicated and time
consuming.
 It requires highly skilled welders.
 Projection welding can’t be applied to a wide range of workpieces.
 Hardware utilized for projection welding are costly.
Applications of Projection Welding
 Projection welding is used for welding studs, nuts to plates, etc.
 Projection welding is also used in the shipbuilding, automotive, and
sheet metal industries.
 It is moreover used for welding the bits of cooler, condensers, etc.
Flash Butt Welding
Flash butt welding is a type of resistance welding that is used in the steel
industry to weld both tubes and rods. In this strategy, two work parts are
welded which will be held tightly during the terminal holders as well as a
high pulsed flow of current inside the 1,00,000 ampere range can be
provided toward the work part material.

Flash Butt Welding

In the two electrode holders, one is long-lasting and other is variable. At

first, current can be supplied, and a spark will be produced when the
changeable clamp is pressed against the permanent clamp due to contact
between the two parts at high current. At the point when the edge surface
methodologies into plastic shape, the progression of current will be halted
too as hub power can be improved to make joint. Due to plastic deformation,
the weld can be formed using this method.
Advantages of Flash Butt Welding
 It is a faster process.
 Preparation of weld surface isn’t needed.
 Power necessity is less.
 Numerous dissimilar metals with various melting temperatures can
be flash welded.
 The process is cheap.
 It offers strength factor up-to 100 percent.
Disadvantages of Flash Butt Welding
 More possibilities of fire hazards.
 Metal is lost during flashing and disturbing.
 Concentricity and straightness of the work pieces during welding
process is frequently challenging to keep up with.
Applications of Flash Butt Welding
 It is utilized for welding metal sheets, bars, rods fittings and so on.
 Flash welding finds applications in car and air craft products.
 It is additionally utilized in home devices, coolers and farm implements.
Successful Welding Process
Three things are crucial for an effective welding process, and they are:
 Time for welding.
 Welding current.
 Welding pressure.

Successful Welding Process

The Figure shows how the energy input to the welding process, welding
strength, and welding current differ with welding time.
The choice of welding time depends upon a few factors, such as, the type
of welding, the thickness and piece of the material being welded, the size
of the weld, and the required welding quality and efficiency. The welder
should likewise consider the type of electrode, welding power source, and
ambient circumstances. A longer welding time might be important for thicker
material.
Specifications for Resistance Welding
The specifications for resistance welding can vary depending upon the type
of welding being performed and the materials being welded. The amount of
electrical current used to heat and fuse the metal parts is known as welding
current, and it is one of the most common specifications.
 Welding Current: The welding current is a major parameter in
welding. It is commonly in the range of 1,000 to 200,000 amperes,
depending upon the material and thickness.
 Electrode Force: The force applied to the terminals during welding is
basic for accomplishing a proper weld. It makes it easier for current to
flow through the workpieces and ensures good contact between the
metals.
 Anode Material: Materials that can conduct electricity well and
withstand the high temperatures generated by welding are required for
electrodes. Common terminal materials incorporate copper and its
alloys.
 Cooling System: Resistance welding creates heat, So for cooling
purpose we need a cooling system . Water cooling is used for this
purpose.
 Welding Machine Control System: Modern resistance welding
machines are equipped with control systems that allow exact change of
welding parameters and high-quality welds.
 Welding Transformer: In welding system transformer plays a major
role because for welding purpose we need more current. So we need a
transformer that should be matched to the specific requirements of the
welding application.
 Safety Measures: In any welding process safety is more important.
For this purpose require a proper ventilation, personal protective
equipment (PPE), safety interlocks on machinery are essential.
Advantages of Resistance Welding
 This method is simple and does not require a lot of skilled labor.
 The resistance welding metal is 20 millimeters thick and 0.1 millimeters
thin
 Automated simply
 The production rate is high Both related and distinct metals can be
welded.
 Welding speed will be high
 It needn’t bother with any flux, filler metal and protecting gases.
Disadvantages of Resistance Welding
 Instruments cost will be high.
 The work segment thickness is limited because of the current
requirement.
 When used with high-conductive equipment, it is less effective.
 It consumes high electric-power.
 Weld joints contain small tensile and fatigue Strength.
Applications of Resistance Welding
 The applications of Resistance welding incorporate the following.
 This kind of welding can be generally used inside automotive
industries, making of nut as well as a bolt.
 Seam welding can be used to produce spill demonstrate joint vital
inside little tanks, boilers, and so on.
 Flash welding can be utilized for welding cylinders and lines.
Comparison Between Resistance Welding and
Electric Arc Welding
Features Resistance Welding Electric Arc Welding

For the most part, AC Both AC and DC supply

Supply supply is utilized for can be utilized in the arc
resistance welding welding.

In resistance welding, In arc welding, the

Power Factor
the power factor is low. power factor is poor

In arc welding, no
In resistance welding, outside pressure is
Requirement of outer tension is required. Subsequently,
External Pressure expected for joining the the hardware is
metals. straightforward and
simple to control.

With the resistance

Filler metal rod is
welding, no filler
Requirement of Filler required for arc welding
material is included any
Material to ensure that the joint
structure for joining the
has sufficient strength.
two metal pieces.

In the event of arc

Resistance welding
welding, the striking
Voltage requires an extremely
voltage is high. Hence, it
low voltage.
needs voltage control.

In arc welding, the arc

In resistance welding
segment temperature is
process the
Temperature extremely high. On the
temperature raise isn’t
off chance that it isn’t
exceptionally high.
dealt with as expected, it
Features Resistance Welding Electric Arc Welding

might harm the work-

piece.

In the resistance
In the circular segment
welding, the intensity is
welding, the intensity is
delivered because of
delivered because of the
Production of Heat the progression of
curve made between the
current primarily
electrode and the work-
through the contact
piece.
resistance.

Resistance welding is Arc welding is

generally appropriate appropriate for fix work.
Suitability for large scale However, it is
manufacturing and incompatible with mass
furthermore for fix work. production.