8. ARC WELDING PROCEDURE
5.5
MAINTENANCE OF THE WELDING EQUIPMENT.
The welding equipment should be routinely maintained according to these instructions. All access and
service door covers should be closed and properly fastened when the welding equipment is in operation. The welding equipment should not be modified in
any way except for those changes and adjustments covered in these instructions. In particular, the spark gaps of arc striking and stabilising devices should
be adjusted and maintained according to these instructions.
5.6
WELDING CABLES.
The welding cables should be kept as short as possible and should be positioned close together, running at or close to the floor level.
5.7
EQUIPOTENTIAL BONDING.
Bonding of all metallic components in the welding installation and adjacent to it should be considered. However, metallic
components bonded to the workpiece will increase the risk that the operator could receive a shock by touching these metallic components and the
electrode at the same time. The operator should be insulated from all such bonded metallic components.
5.8
EARTHING OF THE WORKPIECE.
Where the workpiece is not bonded to earth for electrical safety, nor connected to earth because of its size and
position, e.g. ship’s hull or building steelwork, a connection bonding the workpiece to earth may reduce emissions in some, but not all instances. Care
should be taken to prevent the earthing of the workpiece increasing the risk of injury to others or damage to other electrical equipment. Where necessary,
the connection of the workpiece to earth should be made by a direct connection to the workpiece, but in some countries where direct connection is not
permitted, the bonding should be achieved by a suitable capacitance, selected according to national regulations.
5.9
SCREENING AND SHIELDING.
Selective screening and shielding of other cables and equipment in the surrounding area may alleviate problems of
interference. Screening of the entire welding installation may be considered for special applications.
6. TIG WELDING PRINCIPLES & FEATURES
7. TIG WELDING PROCEDURE
If you have no welding experience we recommend that you seek training from an expert source before using this equipment. Good TIG welding may only be
achieved with continued supervised practice.
Before commencing welding read the safety instructions in Section 1.
6.1
TIG WELDING - GENERAL PRINCIPLES OF OPERATION.
The TIG welding procedure uses the heat produced by an electric arc, struck and maintained
between a Tungsten electrode and a workpiece to soften and fuse the workpiece metal, usually in conjunction with a suitable filler rod. The electrode is held
in an insulated torch which transmits the welding current to the electrode. The torch also has a gas connection which allows an inert gas (usually Argon) to
be dispensed from a ceramic nozzle surrounding the electrode. This produces a shroud of gas around the welding process which protects the electrode and
molten weld pool from oxidation.
6.2
CURRENT DOWN SLOPE FACILITY.
The welder also has a “current down slope” facility which if used gives a gradual turning off of the current. This
function is particularly useful for avoiding the formation of a crater at the end of a weld as the filler rod is still consumed during the ‘down slope’ phase.
6.2.1 On thin pre-prepared material (up to 1mm) welding can be achieved without a filler rod by fusing the edges of the metal together. Most welding however will
be done using a filler rod to complete a joint. This rod is melted in the weld pool but should not make contact directly with the electrode.
It is essential that
operators wear adequately insulated gloves to protect themselves from both the heat of the welding process, metal spatter and any direct contact with the
electrode.
6.2.2 The Tungsten electrode will be consumed during the welding process but at a very slow rate. The tip of the electrode must be periodically inspected and
re-ground if necessary to ensure continued efficient welding. See diagram ‘Condition of electrode tip’.
6.3
TORCH DUAL FUNCTION PUSH BUTTON.
The torch push button can control the switching of the power in two different modes depending on your welding
requirements. These modes are selected using the small toggle switch on the front panel. (See fig.2-2)
6.3.1
Two touch weld cycle.
In this mode the push button is pressed and held down to strike the arc and to continue welding. When the end of the weld is
reached the push button is released and the arc is switched off. The current ‘down slope’ function can be used in this mode if required.
6.3.2
Four touch weld cycle.
This mode allows you to complete long welds without having to continuously hold down the torch button and affords a degree of
control over the weld current using the torch button (See Rapid Touch Function). The push button is first held down which strikes the arc and then
provides power at a base current level as long as the button continues to be held down. Once the push button is released the current rises to the level set by
the welding current control and stays at this level even though the push button has been released. If the button is then pressed and held down again the
current will decrease to the base level and remain there whilst the button is held. When the button is released the current is turned off .
6.3.3
Rapid touch function.
This function is available in four touch mode only. During the course of welding at the current you have set (with the torch button
released) the current can be made to dip down towards base current and back again by momentarily pressing and releasing the torch button.This function
can be used as a sequence of rapid presses which can help to control heat and penetration during difficult welds. At the end of a rapid sequence of presses
when the button is released, the current will remain at the weld current set and the welder will continue to function as previously described in four touch
mode.
WARNING! Use welding head shield to protect eyes and avoid exposing skin to ultraviolet rays given off by electric arc. Wear safety welding
gauntlets.
If difficult welds are to be performed and the welding parameters are unknown, it is advisable to carry out several trial runs on test pieces in order to
determine the right welding current and gas flow.
SWITCH ON
the welder only when you are satisfied that the welder is correctly connected and the work to be done is fully prepared.
7.1
SETTING THE CONTROLS.
7.1.1 Set the required gas flow using the knob on the gas regulator.
7.1.2 Select either the ‘two touch welding mode’ or the ‘four touch welding mode’ using the miniature toggle switch on the front panel.
7.1.3 Set the ‘current down slope’ if required.
7.2
STRIKING THE ARC.
7.2.1
Set the minature toggle switch (see fig.2-4) to the left hand position for HF (high frequency) strike mode and to the right hand position for LIFT strike mode.
7.2.2
HF strike mode.
Press and hold the torch button bringing the electrode tip to within 2 to 3mm of the workpiece. The arc will be struck by high frequency
impulses. When the arc is established, form a molten pool on the workpiece, introduce the filler rod and proceed along the joint. When the arc is difficult to
strike, despite the presence of gas and visible high frequency discharges it is not advisable to carry on for any length of time. Before continuing, check the
integrity of the electrode surface and tip and if necessary regrind the tip.
7.2.3
LIFT strike mode.
Lightly touch the workpiece with the electrode tip. Fully depress the torch button and lift the electrode 2 to 3mm from the workpiece
thus obtaining the arc.
7.2.4 To cease welding release the torch button.
7.2.5
SWITCH OFF
the welder and turn off the gas at the cylinder valve.
The TIG160HF will also perform ordinary ARC welding (without gas) using coated electrodes.(Requires optional ARC Accessory Kit INV/16)
Please note that the way the welding cables are connected to the inverter for ordinary Arc welding may be different to the way the cables are
connected for standard TIG welding. Whilst most stick electrodes are connected to the positive terminal certain types need to be connected to the
negative terminal. It is therefore essential that the user refers to the electrode manufacturers instructions to ensure that the correct polarity is
selected.
8.1
SETTING THE WELDING CURRENTS.
The mechanical characteristics of the weld will be determined not only by the current used but also by other factors such as the diameter and quality of the
electrode itself as well as the arc length, the speed of welding and the orientation of the electrode to the work surface. Unused electrodes should also be
protected from moisture as a damp electrode will affect the quality of the weld.
8.1.1 The following table gives a general guide to the minimum and maximum welding
currents to be used with the different diameter electrodes.
8.1.2 Depending on the diameter of the electrode the current used will have to be varied
depending on the orientation of the workpiece itself. Higher current values will be used for
flat welding whereas the current will have to be reduced for vertical or overhead welding.
8.1.3 The current down slope function is not used during ordinary Arc welding and the
potentiometer should be set to zero.
Electrode diameter
Welding current
(mm)
Min. - Max.
1.6
25
-
50
2
40
-
80
2.5
60
-
110
3.2
80
-
160
Original Language Version
TIG160HF Issue: 1 - 31/10/11
