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 headshield 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 workpiece 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 Switch.
7.1.3. Select the required welding current setting using the current selector dial.
7.2.
STRIKING THE ARC (HF strike).
7.2.1.
There is no need to contact the workpiece, instead bring the electrode tip close to the workpiece and the HF pulse will initiate the arc.
7.2.2.
SWITCH OFF
the welder and turn off the gas at the cylinder valve after welding operations are complete.
These welders will also perform ordinary MMA welding (without gas) using coated electrodes.(Requires optional ARC Accessory Kit INVMMA1/INVMMA2 -
see specifications)
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 manufacturer's 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 headshield 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 workpiece is fully prepared.
8.3.
SETTING THE CONTROLS.
8.3.1. Select the MMA mode using the Operating Switch.
8.3.2. Select the required welding current setting using the current selector dial.
8.4.
STRIKING THE ARC.
Strike the electrode tip onto the workpiece as if 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. 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)
Minimum - Maximum (A)
1.6
25 - 50
2
40 - 80
2.5
60 - 110
3.2
80 - 160
4
120 - 200
Original Language Version
TIG160S, TIG180S, TIG200S Issue: 1 - 05/06/13
© Jack Sealey Limited