– 8 –
2
FIG.
Note: Welding is a mix of science and art and due to the
complex principles and vast differences in parameters
(ie. Material type, position, condition etc.) That
information is well beyond the scope of this manual.
Draper Tools suggest training be obtained from a third
party or refer to a suitable reference book on the subject
additionally; nothing can beat practice using the welder
on scrap material to get a better understanding.
8.2 TIG WELDER, TUNGSTEN
ELECTRODES - SELECTION &
PREPARATION – FIG. 3
The correct selection of tungsten size and type will
vary for each application dependent upon amperage,
material thickness, equipment and shield gas, however
as a general rule for DC output negative electrode
machines a 1.6mm thorium or cerium oxide tungsten
electrode will suffice.
The selection of the ceramic shroud is based on the
tungsten electrode and should be 4 to 6 times the
tungstens diameter. For example a 1.6mm tungsten
could be used with a No.4 (6.4mm) ceramic shroud, a
No.5 (8.0mm) or at the maximum a No.6 (9.8mm).
There are a variety of different tungsten electrodes
available with the most common categories underlined:
Note: The alloy content shown are a guide but generally
range between 1% to 4%.
Before welding can commence the electrode must be
prepared, i.e. the tip ground to a suitable point.
If using a grinding wheel, a dedicated abrasive wheel
must be used to prevent contamination of the tungsten.
The tip must be ground straight, i.e. perpendicular to the
grinder’s drive spindle.
Note: For DC welding the tip should be ground into a
point to help produce a stable arc.
The general rule is to grind the point’s length to match
the electrodes diameter
(A)
.
However for low amperage/smaller diameter electrodes
the points length should be double the electrodes
diameter
(B)
.
With AC welding you mayfind the tip forms itself into a
balled configuration.
3
FIG.
(A)
(B)
Note: During the grinding process thorium alloy
tungsten can release alpha ( ) dust particles and in
some instances beta ( ) and gamma ( ) particles. Avoid
inhalation as they act as a carcinogen.
In addition to dust protection, safety goggles must be
warn to protect eyes from sparks and debris thrown up
by the grinder.
Selection of the appropriate specification electrode is
important to achieve a good quality weld. Seek guidance
if unsure of selection.
8.3 MACHINE OPERATION
No TIG filler wire is supplied with this machine, please
visit drapertools.com to see our range of accessories.
Alternatively, consult your local Draper stockist for
further information.
Prepare the joint(s) to be welded. Select the electrode
suitable for the application and insert it into the electrode
holder as described in the manufacturers literature.
The tungsten should extend 3-6mm past the end of
shroud but no greater than the gas shroud diameter.
With the earth clamp, electrode holder and gas bottle
connected, connect the machine to the power supply.
The power display will illuminate as confirmation. Set
the amperage adjustment appropriate to the selected
electrode size.
Secure the earth clamp to a clean sound section of the
parent metal in the vicinity to the intended weld. With all
safety equipment in place and personal protective
clothing on begin welding.
Note: Ensure the gas bottle regulator is open.
Open the torch gas control valve (where fitted).
Lower the electrode down toward the parent metal.
Allow the tip of the tungsten to touch the workpiece and
carefully lift again, the arc will be established and
welding can commence.
8.4 ARC WELDING, FILLER ROD
(ELECTRODE) SELECTION – FIG. 4
The correct selection of electrode size and type will vary
for each application dependent upon material thickness,
