Capacitor discharge welding is an economical alternative to traditional welding that allows for high production speeds and low distortion welds. It works by using capacitors to store large amounts of energy, then releasing it extremely quickly through a welding tip to form a weld. This localized heating results in a small heat-affected zone. Capacitor discharge stud welding is commonly used and works by passing a large current through workpieces via a stud to generate heat through resistance and fuse materials together in 0.004 seconds. It has advantages like fast welding speed and clean process but requires expensive equipment.

1. Capacitive Discharge Welding
(CD Welding)
Group 5
Muhammad Tasaduq Ilyas (E14-308)
Ahsan Qureshi (E14-323)
Usama Bin Ali (E14-326)
Bilal Asghar (E14-337)
Semester : 6
Welding & Joining processes
Department of Metallurgy & Materials Engineering
University of Punjab

2. Introduction
 CD welding is an economical alternative to
traditional welding processes. Because of its high
production speeds, coupled with low distortion
welds, makes it the best choice for welding high
carbon material and dissimilar metals.
 CD welding uses large capacitors to store energy
for quick release. It allows extremely fast energy
release with large peak currents, more of the
energy goes into weld formation less into heating
surrounding material. So HAZ is localized to small
area around the weld.

3. Capacitor Discharge Stud
Welding
It is the type of CD welding which is being immensely
used in the industry.
Principle
It relies on the principle of metal resistivity to heat and
fuse metal. A large current is passed through work
piece. Energy is dissipated in the form of heat due to
resistance, which melt and fuse the welded material.

4. Working
The process utilizes a powerful bank of capacitors
to store energy at a specific voltage determined by
stud size and material. When a weld is initiated,
this energy is "discharged" through a special
"ignition tip" at the base of the stud, creating an
instantaneous arc which melts both the base of the
stud and the adjoining surface on the work piece.
At the same time, the welding gun forces the stud
into the work piece, resulting in a permanent bond
as the molten material solidifies all in 0.004
seconds.

5. Schematic Diagram

6. Gun

7. Equipment
Standard handgun portable
CD welder

8. Automated
production system

9. Power Supply
DC power supply is used in CD welder
Advantages
 No water-cooling required for electrodes due
to very short weld times.
 Negligible blackening and distortion at weld
joint. No mark on the other side of the weld.
 Welding of similar and dissimilar metals
possible.

10.  High strength welds are obtained.
 Fast production speeds.
 No cover gases or special environment required.
 Environmentally clean as no smoke or fume is
produced.
Disadvantages
 Welding time is not settable.
 Storage is carried out with high voltage.
 Expensive equipment.

11. Applications
 Fabrication of stainless steel impellers.
 In automobile industry.
 Used in water valve to weld brass to steel as
they are dissimilar metal.
 Sheet metal fabrication.
 Aeronautics industry.
 In the welding of battery tabs.
 Used in ware industry such as in stainless
steel cookware to join the handle to the pan.

12. Applications

13. References
 http://www.powerstream.com/
 http://sunstonewelders.com/
 http://www.keystonefastening.com/capacitor-
discharge-stud-welding-process.html
 http://www.artechengg.com/capacitor-
discharge-welding-machines.html

14. Thank you