Different metals have different characteristics that affect their
ability to be welded or cut.
The welding process involves melting the base metal parts and adding
filler metal that has the same melting temperature and characteristics
of the parent metal.
Metals are divided into two categories, ferrous and non ferrous.
Ferrous metals contain iron such as cast iron, mild steel, forged
steel, and stainless steel., where as aluminium is a non- ferrous
metal. Each metal type requires different welding procedures and
filler metals.
These are the four major welding processes that are used both in
industry and for the home hobbyist.
1) Oxyacetylene Welding or Gas Welding.
Uses a gas flame to melt base metals and fuses them together. The gas
flame is created by the combustion of oxygen and a fuel gas such as
acetylene, propane, butane or natural gas. The hottest of any gas
flame is capable of melting most metals.
Gas welding today is generally restricted to welding thin sheet metals
and brazing of mild steel, and copper pipe work. , Braze welding is
used for joining dissimilar metals and metals of different thickness
and often used to repair cracked or broken cast iron.
2) Shielded Metal Arc Welding (SMAW)
Also referred to as stick or arc welding. The process involves heating
the base metal to fusion by an electric arc using a welding electrode.
The covering on the electrode provides both a flux and shielding gas
for the weld.. Electrodes range in thickness from 2 mm for light work
and up to 5 mm for heavy steel.
Stick welding is used for fabrication, construction and repair work,
more suited to metal thickness 4 mm and upwards. Thinner metals are
more suited to the GMAW process.
3) Gas metal Arc Welding.(GMAW)
Also referred to as MIG or metal inert gas welding.
The most versatile and most used of all welding processes. Uses a
continuos wire feed electrode fed through a welding gun along with a
continuos flow of shielding gas.
The advantages of a mig welder are many, the gun is
easy to manipulate and keep at a uniform distance from the weld,
continuos wire feed allows longer welds to be run, the welds remain
smooth and clean because of the shielding gas. You can weld at very
low temperatures allowing welding of 22 and 24 gauge sheet metals.
Disadvantages are outdoor welding situations where the shielding gas
can be blown away in a breeze and in tight situations where the gun
nozzle limits welding.
Ideal for welding mild steel, stainless steel and aluminium.
4) Gas Tungsten Arc Welding (GTAW)
Also referred to as TIG or tungsten inert gas welding
Tig welding is a process that generates an arc between a non
consumable electrode and the work. The electrode and the weld are
protected by a gas shield, and a filler rod may or may not be used.
Tig welding is similar to gas welding and requires more skill. Used
for doing fine work and where a high standard of finish is required
without the need for grinding, such as bicycle frames and food
manufacturing equipment.. As Tig welding is a very clean process its
ideal for welding stainless steel and aluminium.
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