ARC WELDING PROCESSES
The process, in which an electric arc between
an electrode and a workpiece or between two electrodes is utilized to weld base
metals, is called an arc welding process. The basic principle of arc welding is
shown in Fig.1. However the basic elements involved in arc welding
process are shown in Fig. 2. Most of these processes use some shielding
gas while others employ coatings or fluxes to prevent the weld pool from the
surrounding atmosphere. The various arc welding processes are:
1. Carbon Arc Welding
2. Shielded Metal Arc Welding
3. Flux Cored Arc Welding
4. Gas Tungsten Arc Welding
5. Gas Metal Arc Welding
6. Plasma Arc Welding
7. Atomic Hydrogen Welding
8. Electroslag Welding
9. Stud Arc Welding
10. Electrogas Welding
Fig.1: Principle of arc welding |
Fig.2: Arc welding process setup |
Arc Welding Equipment
Arc welding equipment, setup and related tools
and accessories are shown in Fig. 2. However some common tools of arc
welding are shown separately through Fig. below . Few of the important
components of arc welding setup are described as under.
1. Arc welding power source
Both direct current (DC) and
alternating current (AC) are used for electric arc welding, each having its particular applications. DC welding
supply is usually
obtained from generators driven by electric motor or if
no electricity is available by internal combustion engines. For AC welding supply, transformers are predominantly used for almost
all arc welding where mains electricity supply is
available. They have to step down the usual supply voltage (200-400 volts) to the normal open circuit welding voltage
(50-90 volts). The following factors influence the selection of a power source:
1. Type
of electrodes to be used and metals
to be welded
2. Available power
source (AC or DC)
3. Required output
4. Duty
cycle
5. Efficiency
6. Initial costs and running costs
7. Available floor space
Versatility of equipment
Electrode holder |
Earth clamp |
Hand screen |
Chipping and hammer |
Wire brush |
C-clamp
V-block |
2. Welding cables
Welding cables are required for conduction of current
from the power source through the electrode holder,
the arc, the workpiece and
back to the welding power source. These
are insulated copper or aluminium cables.
3. Electrode holder
Electrode holder is used for
holding the electrode mannually and conducting current to it. These are usually
matched to the size of the lead, which in turn matched to the amperage output
of the arc welder. Electrode holders
are available in sizes that range from 150 to 500
Amps.
4. Welding Electrodes
An electrode is a piece of wire
or a rod of a metal or alloy, with
or without coatings. An arc is set
up between electrode and workpiece. Welding electrodes are classified into
following types-
(1)
Consumable Electrodes
(a)
Bare
Electrodes
(b)
Coated Electrodes
(2)
Non-consumable Electrodes
(a)
Carbon or Graphite Electrodes
(b)
Tungsten Electrodes
Consumable electrode is made of
different metals and their alloys. The end of this electrode starts melting
when arc is struck between the electrode and workpiece. Thus consumable
electrode itself acts as a filler metal. Bare electrodes consist of a metal or
alloy wire without any flux coating on them. Coated electrodes have flux
coating which starts melting as soon as an electric arc is struck. This coating
on melting performs many functions like prevention of joint from atmospheric
contamination, arc stabilizers etc.
Non-consumable electrodes are
made up of high melting point materials like carbon, pure tungsten or alloy
tungsten etc. These electrodes do not melt away during welding. But practically,
the electrode length goes on decreasing with the passage of time,
because of oxidation and vaporization of the electrode material during welding.
The materials of non- consumable electrodes are usually copper coated carbon or
graphite, pure tungsten, thoriated or zirconiated tungsten.
5. Hand Screen
Hand screen used for protection of eyes and
supervision of weld bead.
6. Chipping hammer
Chipping Hammer is used to remove the slag
by striking.
7. Wire brush
Wire brush is used to clean the surface to be
weld.
8. Protective clothing
Operator
wears the protective clothing such as apron to keep away the exposure of direct
heat to the body.
I admire this article for the well-researched content and excellent wording. I got so involved in this material that I couldn’t stop reading. I am impressed with your work and skill. Thank you so much. welding machine online
Electric resistance welding
The world owes the invention of electric resistance and spot welding to Englishman Elihu Thomson. This engineer has several patents in the field of spot welding to his name.
Electric resistance welding consists in assembling by autogenous fusion the parts to be welded under the pressure of two metal parts. Who says welding says heat, with resistance welding the heat necessary for welding is provided by the Joule effect (which is the thermal manifestation of electrical resistance, this heat occurs when an electric current passes through any material conductor) of a current of high intensity and low voltage, passing through the parts to be assembled. Indeed, it takes a lot of amps and little voltage. The application of a forging force makes it possible to ensure the metallic interpenetration.
Punktschweißen
As a professional welder, I always recommend a multi-process welder. Because these welders are perfect for every type of welding. However, if you are looking for the best multi-process welder you can visit the Service Welding Supply website.
Weld repairs to aircraft and component parts use such equipment as gas tungsten arc welding (GTAW), gas metal arc welding (GMAW), plasma arc welding, miller syncrowave 350 lx review and oxyacetylene gas welding.