Resistance welding

1. MANUFACTURING
TECHNOLOGY – I
CRAFTED BY:
RAMESH KUMAR A
Assistant Professor
Sona College of Technology
Salem
07-02-2019 05:39 1

2. RESISTANCE WELDING
07-02-2019 05:39 2

3. RESISTANCE WELDING
07-02-2019 05:39 3
 The metal parts to be joined are
heated by their resistance to the
flow of an electrical current
 No fluxes are employed
 The amount of heat generated in
the work piece depends on the
following factors:
 Magnitude of current
 Resistance of current
conducting path
 Mathematically,
H = I V t
= I (IR) t
= I^2 R t
Where,
H – Heat generated in joules
I - Current in Amp
R – Resistance in ohms
t – time of current flow in
seconds

4. TYPES OF RESISTANCE WELDING
07-02-2019 05:39 4
 Spot welding
 Seam welding
 Projection welding
 Butt welding
Upset welding
Flash butt welding
 Percussion welding

5. RESISTANCE WELDING
SPOT WELDING
07-02-2019 05:39 5

6. SPOT WELDING
07-02-2019 05:39 6

7. SPOT WELDING…
07-02-2019 05:39 7
 Carried out by overlapping the
edges of two sheets of metal and
fusing them together between
copper electrode tips at suitably
spaced intervals
 Resistance offered to current as
it passes through the metal
raises the temperature of the
metal between the electrodes to
welding heat
 The current is cut-off and
mechanical pressure is then
applied by the electrodes to
forge the welds
 Advantages
 High production rate
 Very economical process
 High skill not required
 Most suitable for welding sheet
metals
 Dissimilar metals can be welded
 Small heat affected area
 Limitations
 Suitable for thin sheets only
 High equipment cost

8. SPOT WELDING
07-02-2019 05:39 8

9. RESISTANCE WELDING
SEAM WELDING
07-02-2019 05:39 9

10. SEAM WELDING
07-02-2019 05:39 10

11. SEAM WELDING…
07-02-2019 05:39 11
 It is analogous to spot welding
with the difference the
electrodes are in the form of
rollers; and the work moves in
direction perpendicular to
roller axis
 The welding is usually done
under water to keep the
heating of the welding rollers
and the work to minimum,
and thus to give lower roller
maintenance and less
distortion of the work
 2000 A to 5000 A
 5 kN to 6 kN
 1.5 m/min for thin sheet
 Applications
 Pressure tanks (light or leak
proof)
 Oil switches
 Transformers
 Refrigerators
 Evaporators and condensers
 aircraft tanks etc.,

12. SPOT WELDING
07-02-2019 05:39 12

13. RESISTANCE WELDING
UPSET BUTT WELDING
07-02-2019 05:39 13

14. UPSET BUTT WELDING
07-02-2019 05:39 14

15. UPSET BUTT WELDING…
07-02-2019 05:39 15
 To join bars and plates
together end to end
 One bar is held in a fixed
clamp in the butt welding
machine and other in the
movable clamp
 The clamp being electrically
insulated, the one from the
other, and being connected to
a source of current
 Current is ON, the resistance
in the joint causes the ends to
heat up to welding
temperature
 Then current is switched OFF,
the movable clamp forced up,
so that the pressure applied
upsets the parts together
 Applications
 Non-ferrous of bars, rods,
wire
 Steel rails

16. UPSET BUTT WELDING
07-02-2019 05:39 16

17. RESISTANCE WELDING
FLASH BUTT WELDING
07-02-2019 05:39 17

18. FLASH BUTT WELDING
07-02-2019 05:39 18

19. FLASH BUTT WELDING…
07-02-2019 05:39 19
 The parts to welded are clamped
to the electrode fixtures, as in
butt welding but the voltage is
applied before the parts butted
together
 As the parts touch each other,
an arc is established which
continues as long as the parts
advance at the correct speed
 This arc bursts away a portion of
the material from each piece
 When the welding temperature
is reached, the speed of travel is
increased, the power switched
off and the weld is upset
 Applications
 Automobile – body, axles,
wheels, frames and other
parts
 Welding motor frames,
transformer tanks, and many
type of sheet steel containers
such as barrels and floats

20. FLASH BUTT WELDING
07-02-2019 05:39 20