Jasic EVO 2.0 EM-160C - Guide to MIG;MAG Welding

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GUIDE TO MIG/MAG WELDING
Before starng any welding acvity ensure that you have suitable eye protecon and
protecve clothing. Also take the necessary steps to protect any persons within the welding
area.
MIG process descripon
The MIG process was rst patented for the welding of aluminium in 1949 in the USA.
The process uses the heat that is generated by an electric arc formed
between a bare consumable wire electrode and the work piece.
This arc is shielded by a gas to prevent oxidaon of the weld.
In the MIG process an inert shielding gas is used to protect the
electrode and weld pool from contaminaon and enhance
the arc. Originally this gas was helium.
In the early 1950’s the process became popular in the UK
for welding aluminium using argon as the shielding gas.
Development in the use of dierent gases resulted in
the MAG process. This is where other gases were used,
for example, carbon dioxide and somemes users
refer to this process as CO² welding. Gases such as oxygen and carbon dioxide were added and are acve
constuents to the inert gas to improve the welding performance. Although the MAG process is in
common use today it is sll referred to as MIG welding although technically this is not correct.
This process began to prove itself as an alternave to sck electrode (MMA) and TIG (GTAW) oering
high producvity and deposion rates.
The process also helps reduce any weld defects from the increased stop/starts used in MMA. However,
the welder must have a good knowledge of the system set up and maintenance to achieve sasfactory
welds.
The electrode MIG gun is normally +VE and the work return is normally –VE. However, certain
consumable wires somemes require what is called reverse polarity i.e. Electrode –VE or work +VE.
Typically these types of wire are cored wires used in hard facing or high deposion and gasless
applicaons.
Typical welding ranges
Wire Diameter Spray Transfer DIP Transfer
(mm) Current (A) Voltage (V) Current (A) Voltage (V)
0.6 30 ~ 80 15 ~ 18 n/a n/a
0.8 45 ~ 180 16 ~ 21 150 ~ 250 25 ~ 33
1.0 70 ~ 180 17 ~ 22 230 ~ 300 26 ~ 35
1.2 60 ~ 200 17 ~ 22 250 ~ 400 27 ~ 35