8. MMA 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. TIG welding is suitable for all low alloy and high alloy carbon steels and heavy metals copper, nickel, titanium and their
alloys. Fusion welding solders the joint edges. No welding material is required when welding workpieces up to 1mm thickness. Thicker materials require a
suitable size of filler rod made of the same base material. To achieve the best results, ensure that the workpiece is prepared properly, being perfectly clean
with no sign of oxide, oil, grease, solvents etc.
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 the TIG mode using the Operating Modes and Parameters Button.
7.1.3 Select the required setting using the Encoder.
7.2
STRIKING THE ARC (LIFT strike).
7.2.1
The electric arc strike involves the to-and-fro stroke of the Tungsten electrode on the workpiece. This strike procedure causes less electro-irradiated
disturbance and reduces Tungsten inclusions and electrode wear. Rest the electrode tip on the workpiece using light pressure, then raise the electrode
2-3mm with a slight delay to strike the arc. Initially the welding machine delivers an
I
BASE
current briefly before the set welding current is delivered. To
interupt welding operations, quickly raise the torch away from the workpiece.
7.2.2
SWITCH OFF
the welder and turn off the gas at the cylinder valve after welding operations have ceased.
The TIG150T will also perform ordinary MMA welding (without gas) using coated electrodes.(Requires optional ARC Accessory Kit INVMMA1)
Please note that the way the welding cables are connected to the inverter for ordinary MMA 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.
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.
8.2
SWITCH ON
the welder only when you are satisfied that the welder is correctly connected and the work to be done is fully prepared.
8.3
SETTING THE CONTROLS.
8.3.1 Select the MMA mode using the Operating Modes and Parameters Button. Press and hold for Hot Start or Arc Force settings.
8.3.2 Use the Encoder to set the welding current required.
8.4
STRIKING THE ARC.
Strike the electrode tip on the workpiece as if you were striking a match (
DO NOT
hit the electrode on the workpiece as this could
damage the electrode and make strike-up difficult).
8.5
WELDING.
8.5.1
As soon as the arc is ignited try to maintain a distance from the workpiece equal to the diameter of the electrode in use and maintain this distance
throughout the duration of the weld. Remember that the angle of the electrode as it advances should be 20° to 30° from a vertical line over the workpiece.
8.5.2 At the end of the weld bead, move the electrode backwards in order to fill the weld crater and then quickly lift the electrode from the weld pool in order to
extinguish the arc.
8.6
SWITCH OFF
the welder after use.
Electrode diameter
Welding current
(mm)
Min. - Max.
1.6
25
-
50
2
40
-
80
2.5
60
-
110
3.2
80
-
160
4
120
-
200
Original Language Version
TIG150T Issue: 1 - 11/11/11
