Argon welding: equipment and work technology

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

Argon welding method (TIG system) is mainly used to work with thin-walled workpieces with a thickness of no more than 6 mm. According to the execution configuration and types of metal available for maintenance, this technology can be called universal. The limitations of the scope of argon welding are determined only by its low efficiency in working with large volumes. The technique focuses on the high accuracy of the operation, but with large resources.

General principles of technology

This is a type of manual arc welding that uses a tungsten electrode in a shielding gas environment. The melt is carried out by means of an arc excited between the electrode and the target workpiece. During operation, the gas supply and the correct direction of the tungsten must be ensured. To obtain a high-quality weld, the gas mixture must flow constantly and without interruption, but slowly. One ofThe basic principles of argon welding consist in the manual performance of working manipulations, but depending on the technological support, for example, the process of directing the filler material can be automated. The gas is selected based on the characteristics of the metal being welded. Helium and argon are more commonly used, hence the name of the method. In the case of porous structures of workpieces, protective gas baths are used with oxygen supply up to 3-5%. Such an additive increases the protective properties of the weld from the appearance of cracks and exposure to atmospheric air. At the same time, pure argon as such is not able to create a barrier against the passage of moisture, dirt and other particles that can have a direct negative effect on the formed weld structure. External environmental factors and a poorly cleaned part surface can also be sources of foreign themes.

TIG welding machine

Inverters or transformers are used as a current source. More often - the first, because they differ in a more ergonomic device and characteristics optimized for most typical tasks. Inverters can operate in two modes - with DC or AC supply. For maintenance of solid metals (for example, steel), direct current is used, and for soft ones (aluminum and its alloys), alternating current is used. A modern device for argon welding is provided with the ability to fine-tune the current, has protection against overheating and overvoltage, and in some modifications, a display that reflects all the mainparameters. Recently, modifications with facilitated arc ignition and stabilization of welding parameters are also in demand. These are the Hot-Start and Arc-force functions, respectively.

Hardware Specifications

Choose inverters by voltage, weight, power, welding current spectrum, availability of certain functions and dimensions. The average ranges of the main operating parameters of an argon welding machine can be represented as follows:

• Power - from 3 to 8 kW.
• Current values - minimum 5-20 A, maximum 180-300 A.
• Voltage - 220 V for household models and 380 V for industrial.
• Weight - from 6 to 20 kg.

To perform simple operations, inexpensive models with a maximum current of about 180 A are used. Moreover, in such equipment, the lack of power is usually compensated by a high coefficient of turn-on time duration - an average of 60-70%. This means that the operator will be able to work for 7 minutes without stopping the process to cool the apparatus and, for example, rest for 3-4 minutes. Professionals, on the other hand, mainly use powerful devices powered by three-phase 380 V networks. The advantages of such devices include the ability to weld with voltage surges up to 15%, smooth adjustment of the current strength and an efficient cooling system.

Additional equipment

In addition to the current generator, the work will require a cylinder with a gas mixture, a burner, electrodes and filler wire. The cylinder has a reducer in the design with adjustable gas supply volumeand a hose connected to the tool. A torch in the form of a gun is used to direct the shielding gas. It connects to the cylinder hose, and fixes the tungsten electrode in the holder. Buttons are provided on the burner handle to turn on the gas and current supply. The parameters of the argon welding torch are selected according to the format of the electrode and the maintenance requirements of the target part. Dimensional and structural characteristics, nozzle throughput, etc. are taken into account. As for the filler wire, it is not always used - usually in cases of working with thick workpieces made of carbonaceous metals. This is a metal bar that can also be welded.

Conditions for obtaining high-quality welding

Mainly the success of the operation will be supported by the skills of the performer. An experienced master is distinguished by the ability to hold the burner in the correct position for a long time, as well as to correctly supply filler materials, if they are required in solving a specific problem. In addition to the skills of the master, the quality will be determined by the observance of the welding technology. There are many nuances and subtleties both in the organization of the process and in the course of the physical performance of the work. For example, not everyone knows that the burner must be held at an angle of 20-40 ° relative to the direction of thermal exposure. Ignoring this rule, you can get a fragile and unreliable connection. Also, the argon welding machine itself is of great importance in obtaining a high-quality result. And it's not even about the technical and operational parameters,but in the reliability of the tool, the ergonomics of its design and the effectiveness of the functionality.

Preparation of material for welding

Before welding, clean the surface of the target part. At the first stage, physical processing is performed, and then degreasing. Oil and grease stains are removed with acetone or solvents for metal surfaces. There is another trick related to the preparation of parts with a thickness of more than 4 mm. The so-called cutting of edges is carried out. They are beveled so that the weld pool can later be below the surface of the part. This will allow you to more effectively form a connecting seam. Before working with thin-sheet material, the flanging technique is also used, in which the edge is bent at a right angle. In order for argon welding to leave behind a minimum of burns and deformations, the oxide film is also removed from the workpiece. For this operation, you can use abrasive materials with tools. For example, the manual process often uses a file or sandpaper.

Workflow

The mass cable is attached to the workpiece, the burner is connected to the inverter and the gas cylinder. The master takes the burner in one hand, and the filler wire in the other. Next, proceed to setting the operating parameters of the equipment. It is necessary to set the optimal current strength, based on the parameters of the part. How to choose the optimal mode? In the case of large-format base steels and their alloys, argon welding is carried out on direct current.polarity. If we are talking about non-ferrous metals, then alternating current with reverse polarity will create optimal conditions. Before the immediate start of the operation, it is necessary to turn on the gas mixture supply for about 15-20 seconds. After that, the burner nozzle is brought to the surface of the part, and the distance from the electrode should be 2-3 mm. An electric arc will be formed in this gap, which will further ensure the melting of the edge and filler rod.

Features of working with titanium

In the case of titanium, the difficulties are due to its chemical activity, which occurs when interacting with a gas mixture. In particular, during the melt, oxidation occurs, a hard film is formed, and hydrogen reduces the quality of the weld. Moreover, due to the low thermal conductivity of titanium, it becomes necessary to re-weld around the existing joint, which is provided in the first pass by argon welding. With your own hands, you can perform high-quality processing of this metal using a combination of tungsten electrodes and a filler rod, maintaining an angle between these elements of 90 °. At least this recommendation can be used when working with sheets from 1.5 mm.

Features of working with copper

The problems of welding this metal are somewhat similar to those discussed above. In the course of work, the same oxidation is observed, leading to a non-uniform weld. There are other features associated with copper billet oxide due to reaction with hydrogen. Pairs are formed that fill the structure of the junction, whichlogically leads to the preservation of air bubbles. How to cook copper with argon welding to eliminate such effects? Work only with reverse polarity or alternating current. The gas used is argon, and the electrodes are not tungsten, but graphite. Unlike titanium welding, the edge melting method is used without a filler rod.

Features of working with aluminum

Perhaps, this is the most capricious metal in welding, which can be explained by the difficulty of holding the shape during the melt, high oxidizability, high thermal conductivity and a tendency to form cracks, dents and other defects. The argon mixture in this case will perform not only the role of protection against oxygen, but will also act as an activator of the electrically conductive plasma. During the heating process, a refractory layer will form, which will need to be destroyed under conditions of reverse polarity or alternating current. In many ways, the quality of argon welding of aluminum will also depend on the degree of intensity of the direction of argon. So, when working with an aluminum sheet 1 mm thick at a current strength of not more than 50 A, the consumption of inert gas will be 4-5 l / min. Thick parts up to 4-5 mm are cooked at a current of 150 A with an argon supply of up to 8-10 l / min.

Compliance with safety measures when welding

Even with minor work, a whole range of protective measures should be provided, including the following:

• To prevent thermomechanical effects in the form of splashing of the melt with contact with the skin, it is necessary to use special equipment– a jacket, trousers, gloves and sleeves made of heat-resistant dense fabric.
• Minimize the risk of fire during argon welding by cleaning the workplace from flammable substances and objects. The equipment, its connection channels are carefully checked, and gas communications are pre-purged.
• The issue of electrical safety is also important. Equipment must be dielectric coated and wiring must be grounded and short circuit protected.

Advantages and disadvantages of the method

One of the main advantages of the technology is its versatility and the ability to work with different metals at high speed. As already mentioned, even alloys that are afraid of interaction with oxygen can be successfully serviced under certain conditions. Another plus is expressed in a protective gaseous environment, due to which the risk of pore formation and foreign inclusions in the weld structure is reduced. In many situations, it is required to enclose the working area as much as possible so that the rest of the surface remains untouched. And in this sense, argon welding will be the best solution, since heating is carried out locally and does not deform third-party elements and structural parts. If we talk about the shortcomings, then they are few. Firstly, it is the complexity of the physical execution of the task, which requires certain skills and knowledge. Secondly, a high load on the network with high electricity costs is inevitable.

Conclusion

Today anyone can implement TIG weldingwishing, acquiring the appropriate equipment and consumables. For household tasks on the farm, for example, you can get the Resanta SAI 180 AD device, which will allow you to perform functional and productive argon welding. Equipment of this type with a current of 180 A costs about 18-20 thousand rubles. Professionals are recommended models like "Svarog" TIG 300S and FUBAG INTIG 200 AC/DC. They are distinguished by high power of about 6-8 kW, current strength from 200 A, but they also cost at least 25 thousand rubles. Such welding equipment is often used in construction, specialized auto repair shops and large industries.