Thermal Overload
All Welders have a feature called a duty cycle.
Duty cycle on a welder refers to the time in which the
welder operates during normal welding.
A welder can only weld for a certain continuous period of
time before it requires to cool down.
If the internal components of the welder should become
hot the welder could overheat. If the welder overheats the
Thermal Overload Protection feature will automatically
shut down the welder.
THIS CAN OCCUR IN HEAVY USE AND DOES NOT
INDICATE A FAULT.
The Welder will cease to weld and the Thermal Overload
LED light will turn on. This LED indication light is just
to inform you that your welder is becoming too hot and
requires to cool down to protect the internal components
of the welder. Do Not turn your welder Off as the welder
has an internal cooling fan and this will assist your
welder to cool down quicker. Reducing the cooling time
will enable you to get back to your welding job quicker.
Depending on how many Amps or how heavy the welding
you are doing the cooling time may take up to 10 Minutes
for your welder cool down so you can return to your
welding job.
IF YOUR WELDER OVERHEATS AND THE THERMAL
OVERLOAD PROTECTION ENGAGES DO NOT TURN
YOUR WELDER OFF AS THE FAN WILL ASSIST IN
REDUCING THE COOLING TIME.
Travel Speed
The electrode should be moved along in the direction of the joint being welded
at a speed that will give the size of run required. At the same time, the electrode
is fed downwards to keep the correct arc length at all times. Excessive travel
speeds lead to poor fusion and lack of penetration. While too slow a rate of
travel will frequently lead to arc instability,slag inclusions and poor mechanical
properties.
Electricity
The electricity flows through the electrode cable to the attached electrode. The
electricity will not leave the electrode unless it touches an earthed object.
Electricity always finds the fastest path to the earth. When the earth cable
clamp is connected to the metal work piece a direct earth connection is created
back to the welder. When the electrode makes contact with the earthed work
piece an arc is created. The electricity flows through the electrode, the metal
work piece and then through the earth cable straight back to the welder.
Earth Clamp
Prior to connecting the earth clamp it may be necessary to clean the surface
of the work piece using the metal brush. Attach the earth clamp firmly to the
work piece ensuring there is good metal to metal contact. Clamp it where it
will not be in the way. This clamp provides an earth connection back to the
welder. Always ensure the welder is disconnected from the power supply before
attaching electrodes into the holder.
Welded Joints
Butt Joint
Is the joining of two pieces of
material together along a single
edge in a single plane. Two
sheets of metal are laid side-by-
side and joined together along a
single joint
Fillet Joint
Is a type of joint used for welding
pieces or plates in which the
angle between them varies from
0
°
to 180
°
. The edge of one plate
is brought against the surface of
another not in the same plane.
The joint can be welded on one
or both sides.
Lap Joint
The edges of a plate are lapped
one over the other and the edge
of one is welded to the surface of
the other.
Corner Joint
A corner joint consists of two
pieces of material joined at their
edges to form an “L” shape.
ARC WELDING
Electrodes
Always store the electrodes in a dry place protecting them from moisture.
Should electrodes become damp or moist, bake them in an oven at 200 - 250˚C
for 2 hours. Unless the electrodes are vacuum packed, basic coated electrodes
will always require such baking prior to use.
Metal arc welding electrodes consist of a core wire surrounded by a flux
coating. The flux coating is applied to the core wire by an extrusion process.
The coating on arc welding electrodes has a number of purposes:
•
To provide a gaseous shield for the weld metal, and preserve it from
contamination by the atmosphere whilst in a mol ten state.
•
To give a steady arc by having ‘arc stabilisers’ present, which provide a
bridge for current to flow across.
•
To remove oxygen from the weld metal with ‘deoxidised’.
•
To provide a cleansing action on the work piece and a protective slag cover
over the weld metal to prevent the formation of oxides while the metal is
solidifying. The slag also helps to produce a bead of the desired contour.
•
To introduce alloys into the weld deposits in special type electrodes.
Arc Length
To strike the arc, the electrode should be gently scraped on the work until
the arc is established. A simple rule for the proper arc length; it should be the
shortest arc that gives a good surface to the weld. A very long arc produces
a crackling or spluttering noise and the weld metal comes across in large,
irregular blobs and gives a rough surface finish to the weld. A short arc is
essential if a high quality weld is to be obtained but a excessively short arc will
cause sticking of the electrode and result in poor quality welds. For down hand
welding is to have an arc length no greater than the diameter of the electrode.
Electrode Angle
The angle that the electrode makes with the work is important to ensure a
smooth, even transfer of metal. When welding in down hand, fillet, horizontal
or overhead the angle of the electrode is generally between 5 and 15 degrees
towards the direction of travel. When vertical up welding the angle of the
electrode should be between 70 and 80 degrees to the work piece.
IMPORTANT INFORMATION
