Friday, October 22

understanding TIG or GTAW welding

Without welding, it is difficult to imagine aviation, space, engineering and construction, welding is in demand in everyday life. The most diverse methods of joining metals and their alloys are widely used at the present time, and an inexpensive but effective TIG welding method occupies a separate place. We will review the working methods, technologies and metals that are welded using this method. Special attention should be paid to equipment, equipment and consumables, as well as to the principles of work in an inert gas protective environment.

Advantages and disadvantages of argon arc welding

One of the methods of metal welding is MMA, in which work is performed by melting coated electrodes, alternating or constant (AC / DC) output current. In addition, semi-automatic MIG / MAG welding in shielding or active gas is widely used. The next intermediate in price category is TIG welding, which is also called the argon-arc method. In it, the process of welding metals by an arc of a short circuit is carried out by a non-meltable tungsten electrode in a protective gas environment that prevents oxidation in the open air.

As a source of AC / DC current, a welding inverter is used, equipped with a Euro-connector, through which gas and output current are supplied to the torch, and control signals also pass. In contrast to the MIG method, where a movable wire is used as an electrode, TIG welding uses a refractory tungsten electrode with a high melting point. Gas is supplied through a burner with a grid, and then, with a delay of 1 second, voltage is supplied. This is done so that welding starts in a shielding gas medium, which is supplied under pressure and being heavier than air prevents the oxidation of workpieces.

A better understanding of what TIG welding is will help assess the advantages and disadvantages of this method of joining metals, especially in comparison with the MMA and MIG methods. The advantages of argon arc welding include the following parameters:

the ability to work with both thin-walled parts and workpieces of significant thickness;
work in AC / DC modes;
wide ranges of adjustment of welding current parameters;
the use of non-combustible gases, which increases the safety of work;
refractory electrodes of reusable use;
reliable, collet clip of a torch for replaceable electrodes of various thickness;
the presence of an oscillator for improved ignition of the arc;
the ability to work with forward and reverse polarity.

This method has certain disadvantages that do not significantly affect the workflow. They are as follows:

low welding speed compared to other methods;
the need to work in enclosed spaces in order to eliminate gas overruns;
low mobility;
manual feed of welding wire .

Composition of equipment and scope of TIG welding

Each type of welding has its purpose, advantages and disadvantages, as well as a set of necessary equipment and consumables for high-quality work behavior with the best result. The list of TIG welding equipment includes the following components:

MMA + TIG inverter with an adapter for the gas mixture and a Euro connector, with adjustable output parameters, with input AC power 220/380 V and current from 10 A to 180 A;
Eurohose used to supply inert gas, control signals and welding current;
gas supply hoses from cylinders;
cylinders equipped with reducers and manometers;
torch with a control button and a collet clamp of a tungsten electrode;
welding or filler wire, similar in composition to the working material;
inert gas or its mixture with CO 2 to create a protective environment in the weld pool;
refractory tungsten electrodes.

Tig welding is used in industry, construction and domestic needs. The great capabilities of the method allow its use in welding not only various metals, but also their combinations, as well as alloys. The following materials can be fused with direct and alternating pulse current:
structural and carbon steels;
various aluminum alloys;
stainless steel, including for sanitary-hygienic and food needs;
titanium alloys;
copper, brass and bronze, as well as combinations thereof;
galvanized metal and nickel-plated surfaces.

To ensure good welding quality, it is necessary to monitor the purity of the tungsten electrode and sharpen it regularly, since the thickness and cleanliness of the seam made by the TIG method depend on it to a greater extent.

Operating modes and TIG welding technology

Metals and alloys, depending on the physicochemical properties, are welded in different modes of operation of the current source. The reason for this is the refractoriness of the oxide film or the thickness of the workpieces. At various welding modes, the required penetration depth is achieved in relation to a specific task and a specific metal. The following operating modes are available for the TIG method:

a method using direct current (DC) of various polarity;
work on an alternating output, high-frequency current (AC) using various current-voltage characteristics for a gentle effect on parts;
Method of non-contact high-voltage ignition of an arc using an oscillator that forms a discharge.

Direct current is used when welding aluminum and magnesium alloys with reverse polarity, which provides good strength characteristics of the weld and allows you to destroy the refractory oxide film on the surface of the workpieces. In addition, appropriate welding rods are used, which are fed into the melting zone manually by translational movements. Other types of metals are welded with direct current of direct polarity with filler wire and selection of current strength.

Work using alternating current is called pulsed welding, since the metal is heated at the peak values ​​of high-frequency oscillations. At basic indications of the current strength, the heating of the workpieces is reduced, which prevents overheating (especially thin-walled) of the metal. The refractory electrode must be kept at an angle close to 90 °, but with an inclination towards the direction of the welding process without transverse movements, and the bar should be fed with light translational vibrations into the weld pool.

The oscillator by applying to the workpiece a high-voltage low-voltage voltage allows the ignition of the arc in a non-contact manner, which prevents contamination of the working surface of the electrode. As for inert argon, it is produced in the highest and first degree of purification and is often used in a mixture with helium. This combination allows you to achieve the best result, but sometimes argon is used in a mixture with carbon dioxide to save.

We tried to tell you as much as possible about TIG welding and its application when working with various metals and in constant and alternating current modes. The method requires costs and a certain qualification, but having mastered it, you will get a universal way to connect a wide variety of parts and the possibility of repairing metal products of different thicknesses.

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