Impax IM-TIG200 Instruction Manual page 24

MMA OPERATION
Wear a leather apron and gauntlets. This will
protect you from being burnt or sparks setting
alight to your clothes.
Place the work so that the direction of welding
is across, rather than to or from, your body. The
electrode holder lead should be clear of any
obstruction so that you can move your arm
freely along as the electrode burns down. If the
lead is slung over your shoulder, it allows greater
freedom of movement and takes a lot of weight
off your hand. Be sure the insulation on your
cable and electrode holder is not faulty,
otherwise you are risking an electric shock.
Striking The Arc
Holding a face mask in front of your face stroke
the electrode point on the workpiece as if
striking a match.
Maintain a steady gap between the end of the
electrode and the workpiece of approximately
2mm (Fig.8).
Fig 8
Maintain this distance as constantly as possible
during the weld remember that the angle of the
electrode to the work piece must be 20-30°
(Fig.9).
Fig 9
2mm
20º-30º
Do not hit the electrode on the workpiece as
this may damage the electrode. Withdraw with a
clean movement at the end of the welding run.
Note: This is the most difficult aspect for most
beginners. It is recommended that you practice
on some scrap material in order to get a feel of
the operation.
If the electrode is not withdrawn quickly enough
once the arc is primed, there is a possibility that
the electrode will weld itself to the workpiece.
Should this happen, give it a sharp tug to free it,
and try again. If this fails to free it, turn off the
machine immediately as it will quickly overheat.
If you withdraw the electrode too far once the
arc is primed, you will lose the arc and have to
try again.
Inspect the job carefully. With a correct
combination of electrode size and current
setting the area of weld should be complete
fusion of the electrode and parent metal/s. Any
slag which forms on the surface should be
chipped away with the pick/brush supplied.
If the resultant weld looks messy and irregular,
this is an indication of porosity or slag
contamination, and you have almost certainly
failed to achieve the correct combination. This is
a common problem, so do not worry as practice
will quickly cure this.
Arc Length
The securing of an arc length necessary to
produce a neat weld soon becomes almost
automatic. You will find that a long arc produces
more heat. A very long arc produces a crackling
or spluttering noise and the weld metal comes
across in large, irregular blobs. The weld bead is
flattened and spatter increases. A short arc is
essential if a high quality weld is to be obtained
although if it is too short there is the danger of it
being blanketed by slag and the electrode tip
being solidified in. If this should happen, give
the electrode a quick twist back over the weld to
detach it. Contact or "touch-weld" electrodes do
not stick in this way, and make welding much
easier.
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