Welding Techniques; Mma Welding - Welbach AMPERO 225 Manuel D'utilisation

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17. MODE - MODE SELECTOR - TIG / PULSE TIG / MMA / AUTO.
18. MMA - means welding with shielded electrode.
19. PULSE TIG - means TIG welding with pulse function. This function allows to reduce
the amount of heat provided to the material. Ideal for welding of thin metal sheets.
20. TIG - means TIG welding.
21. AUTO - means automatic welding during which nothing can be adjusted except for
current.
22. "AC/DC SWITCH" - TIG welding is divided into AC (alternating current) and DC
(direct current) welding.
23 AC MODE - in this mode, it is possible to weld aluminium and non-ferrous metals
(brass, bronze).
24. DC MODE - his this mode stainless steel, alloy steel (VA) and low-allow steel can
be welded.
25. "4T/2T SWITCH" - when welding in TIG mode, the user can select "2T" mode
(without sustain) and "4T" mode (with sustain). The "4T/2T" functions are available
both in the DC and AC mode.
26. "2T FUNCTION" - means commencement of welding after the button on the
torch is pressed and stopping of welding after the button on the handle is released
27. "4T" FUNCTION - pressing the button on the torch opens the solenoid valve,
causing initial gas outflow. Initial gas outflow causes electric arch striking. The
current will have the initial current value upon ignition. After the button is released,
the value of the output current increases to the welding current value. The welding
process is stopped after repeated quick press of the button on the torch.
28 LED - digital display.
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29. POWER - power on lamp.
30. WARNING - THERMAL OVERLOAD CONTROL LAMP - in case of overheating, the
lamp lights up and the device is switched off. Do not attempt to start welding again,
leaving the device with fans switched on. The lamp switches off automatically after the
device is cooled down. Note the rated operating cycle.

5. WELDING TECHNIQUES

5.1 Preparation of workpieces for welding operation
Before elements can be welded, they must be properly prepared. The edges must be cleaned from cinder, rust,
contamination and grease. Failure to clean the edges causes emission of gases, generation of oxides, weld inclusi-
ons, porosity. Cleaning can be performed mechanically or chemically. Mechanical cleaning is performed by means
of a wire brush, abrasive paper, grinding discs, sanding or kibbling. Chemical cleaning must be performed using
substances prepared specially for this purpose.
It is also necessary to prepare the edges of the welded elements in a proper manner (see figure below). Proper
preparation of the edges guarantees proper weld durability.
As can be seen in the figure above, elements measuring up to 4 mm in thickness are not bevelled, it is sufficient
to make one clearance.

5.2 MMA welding

Check proper functioning of the equipment prior to commencement of work. For the welding process to be safe
and efficient, the power source and the conduits must be technically faultless and without damage. Same goes for
the electrode. Welding should be started by rubbing or hitting the electrode against the detail. When the electric
arc starts to burn, the electrode must be moved along the welded edge, simultaneously, maintaining constant
arc length. Check proper functioning of the equipment prior to commencement of work. In order to perform
welding in a secure and efficient manner, both the welder and the conduits must be technically operative, without
any visible defects, the same applies to the electrode. The handle with the electrode should be inclined towards
the welding direction (figure). It assures better fusing and a narrow weld site.
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