In industrial context, welding refers to a
fabrication process that joins materials such as metals and
thermoplastics, by causing coalescence. This is typically done by
softening the work pieces and adding a filler material, which is often
a welding rod, to form a pool of molten material that cools to become a
strong joint. Various processes and energy sources are used for
welding, such as gas flame, electric arc, laser, electric beam,
friction, and ultra sound.
Welding machines can be broadly
classified into different categories depending on the type of welding
processes and equipment used during the process. Some welding machines
use transformers for converting high voltage, low current electricity
into high current low voltage, often between 17 to 45 volts and 190 to
590 amperes. These types of welding machines are the least expensive
and allow welders to select the output current by either moving the
core of the transformer in and out of the magnetic field or by allowing
the welder to select from a set of taps on the transformer.
Some
welding machines use an internal combustion engine or an electric motor
to drive the alternator or generator present in these machines. The
process used is similar to transformer based welding machines as power
is first converted into mechanical and back to electrical energy to
achieve the step-down affect.
Inverter based welding machines use
high-power semiconductors such as the IGBT for building a switching
power supply capable of handling high loads of arc welding. These
machines convert utility electricity into high voltage and store it in
a capacitor bank. The stored energy is then transferred to a secondary
transformer for producing the desired welding current.
Welding
machines have simplified different types of machining jobs undertaken
in small and large manufacturing companies. Automated welding machines
are also in use and have helped in increasing the effectiveness of
welding processes.