MIG Welding
Overview
Welding: a process of joining two materials that
coalesce at their contacting surfaces through the
application of heat.
• Advantage: portable, permanent, stronger than
the parent materials with a filler metal; the most
economical method of joining in terms of material
usage and fabrication costs.
• Disadvantage: expensive manual labour, highenergy and important safety considerations; does
not allow for disassembly, defects can be
concealed.
MIG welding
A continuously fed metal electrode (wire) contacts
the base metal and produces heat through an ‘arc’ of
electrical current. The arc is shielded by an inert gas
to inhibit oxidisation.
Typical setup for wire speed
• The wire feed rate or speed is set using the dial on the
wire controller.
This setting increases or decreases the current or heat.
This setting is measured in amps.
• Ideal settings can be fixed and monitored by the amp
meter on the front panel of the welder.
• Ideal settings can be found in the wire manufacturer’s
data book, related to the appropriate current.
Types of joint
Butt joint
http://www.youtube.com/watch?v=XYBjLvxG5z0
Corner joint
http://www.youtube.com/watch?v=sNSHDork_Yw
Lap joint
http://www.youtube.com/watch?v=JqFp5kCeTA0
T joint
http://www.youtube.com/watch?v=NNz_Bbo4Ojg
Technique
Speed of movement is very important.
The angle and direction for a right-handed
person.
(Left-handed people move to the right, angled to the left.)
Method of welding
• The following films will show you how to use a MIG welder.
Watch and listen very carefully, taking notes, to remember all
the tips that are given in each clip. Remember, the best way to
learn how to weld is practise, practise and practise some
more.
• http://www.youtube.com/watch?v=ZNyAzVQTY6Y&feature=re
lated
• http://www.youtube.com/watch?v=lzBGZaS1apw&feature=rel
ated
• http://www.youtube.com/watch?v=NCrJWoid9Y&feature=related