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Posts Tagged ‘irregular shapes’

Hello,

MIG Welding is the other main type of welding done today.  Today we
explore it in depth.

MIG(GMAW) or Wire Feed Welding Process Overview
This process is called by many names and it basically is a welding
process that uses an arc to heat metal that needs to be joined. The
welder uses a continuous feed filler metal (a consumable) electrode
and this is used on the work-piece. This type of welding also must
use a shielding that is provided by a gas or a mixture of gasses.

This type of welding is also called short circuit transfer. In the
MIG process, when the wire actually touches the metal to be
connected, it lets go of the metal that does the welding. This
makes sure that metal doesn’t transfer across an arc so there is no
puddling.

Also known as gas metal arc welding, the MIG(GMAW) process uses a
metal gun to provide this service instead of a torch so that you
get a direct current going to the metal. You can use both constant
current and alternating current systems to also produce this method
of welding.

GMAW uses four ways to transfer metal. These are:

Globular — this method is difficult and used the least because it
has a tendency to spatter because the gun will move to a high heat
without warning. This makes the welding surface come out with
flaws.  This method uses carbon dioxide so the electrode tends to
produce a ball of melted metal that cases irregular shapes that are
bigger than the electrode. They then drop and falls onto the piece
you are working on which causes a spatter. This is difficult to
control as you would imagine.

Short circuiting — this uses a smaller current than the globular
method but it still uses carbon dioxide. Because of the lower
current you can actually weld thinner metals together with this
method. This method is similar to the globular method because drops
of melted metal from the electrode still forms, but it causes the
electrode to short circuit instead of the drops falling on the
work. This closes off the arc but comes back again because the
surface tension pulls the metal goblet from the tip.

Spray — this was the first method for transfer used with GMAW and
used to weld aluminium and stainless steel. The difference with
this process is that the electrode metal passes through an electric
arc that is stable and goes all the way to the workplace. This
stops spattering and you get a weld finish that is higher quality
than in other methods. You also will watch as the current and
voltage increases so you get small, vaporized steam droplets
instead of large globules.

Pulse spray — this last one is a newer way of doing this type of
welding that uses a continuous current that pulses and melts the
filler wire. In each pulse a small droplet of metal will fall.

This also allows the welder to use a lower current. The welder gets
a more stable arc and this stops spatter and the short circuiting
process. Because this process is slower, argon gas is used instead
of carbon dioxide as the shielding gas.

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Have a good one,
Ivan Irons
WelderWorld.com

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