TYPES OF METAL WELDING AND THEIR BRIEF DESCRIPTION
TYPES OF METAL WELDING AND THEIR
BRIEF DESCRIPTION
The technological components of the welding process were known as early as the 17th century. Then they were represented by casting and black smithing. "Modernization" began after the discovery of such a phenomenon as an electric arc. The development of welding received an additional impetus with the invention of a powder coating for electrodes. But the main leap fell at the end of the 20th century, when laser, ultrasound and plasma technologies became available. The introduction of electronics made it possible to automate the welding process, increase the accuracy of work and productivity.
Currently, there are three types of welding, which differ in the type of energy used to perform the work:
thermal;
mechanical;
thermomechanical.
CONTENT
Thermal welding
Electric arc contact welding
MMA-manual arc welding
Argon TIG welding
MAG-semi-automatic welding
Submerged welding
Gas-plasma
Electroslag
Plasma
Thermomechanical welding class
Thermal welding
To perform portable welding machine work, heat will be required. Under the influence of high temperatures, the joints of the connected blanks are melted and, cooling down, are fastened together, and subsequently crystallized. The flame of a gas burner, an electric arc or a plasma stream serves as a heat source.
Electric arc contact welding
The most widespread are the electric arc welding machines. To heat and melt the metal, an electric arc is used, which is a discharge between the cathode and the anode. At the same time, high-power thermal energy is released. Acting on the metal billet, it leads to its melting, followed by the formation of a welding bath.
After the arc fades, the cooling and crystallization of the melt immediately begins. As a result, a compound is formed that is comparable in composition and strength to the metals that were welded. There are several types of electric arc welding.
MMA-manual arc welding
It is used with piece electrodes, which are a metal rod with a coating. The process takes place under the influence of direct or alternating current. The coating of consumables melts, releasing gases that form a cloud to protect the metal being welded from oxidation. In addition, various chemical compounds are included in the coating, which serve as an additive to the welding bath to change the properties of the welding seam and support the stable burning of the electric arc.Gorenje
Devices – inverters, rectifiers, transformers-allow you to perform work in any spatial position. If you choose the right consumables, you can weld any metals: ferrous, non-ferrous, alloyed, etc. It is important to emphasize that the holders can penetrate into hard-to-reach places where using another type of welding is impossible.
MMA welding is suitable for both professionals and beginners. It is widely used in construction, installation of metal structures, in various branches of heavy industry, in private entrepreneurship. It is necessary for a small workshop for the manufacture of metal structures, a car service station, a large machine-building plant. It is indispensable in the household when you need to construct something from metal yourself or repair a leaky metal frame.
What is manual arc welding
Argon TIG welding
Tungsten, non-melting, graphite, and carbon electrodes are used. As an inert gas, argon, nitrogen, helium or a mixture of these gases is used, depending on the metals being combined. The process is characterized by the fact that the weld consists exclusively of metal workpieces. Only an additive is added – a metal rod or strip, which is identical in composition to the metals being welded. Inert gases are necessary to protect the working area from atmospheric air, to prevent metal oxidation and to ensure the stability of the electric arc gorenje.
In the process of performing welding work, alternating or direct current is used. The relatively low productivity is compensated by the high quality of the welded joint. The process is characterized by high labor intensity and requires a lot of practical experience from the specialist. The use of TIG is justified in cases where it is necessary to impose a responsible seam that must withstand high loads, or in cases where great attention is paid to the aesthetic side of the issue.
Argon welding is in demand for sealing oil and gas pipelines, tanks for the food industry, tableware; in the manufacture of high-pressure vessels or microchips. It is indispensable for connecting thin-walled blanks and sheet materials. Welding allows you to work with a large list of metals: stainless, carbon, alloy steel; magnesium, titanium, copper.
MAG-semi-automatic welding
As an additive material, a wire is used, which, like an electrode, melts under the influence of high temperature. The wire enters the working area through a burner, where an inert or active gas is supplied in parallel. The composition of the protective gas directly depends on the type of metal being welded. It works exclusively with a constant electric current. During the application of active gases, a lot of splashes are formed, and the seam turns out to be sloppy. But this is more than compensated by the high performance of the installation.
This kind of equipment is very popular among professionals and a large audience of amateurs. Partly due to the automatic supply of consumables to the welding zone and the possibility of electronic adjustment of settings. The technology is especially popular among European and North American specialists. Semi-automatic machines weld a wide range of metals: low-alloy and high-alloy steel, most grades of cast iron; manganese, copper, aluminum, nickel, as well as their alloys. The equipment allows you to perform the most complex multi-type connections.
Submerged welding
When welding metal workpieces, different flux powders are used. They are necessary in order to provide the working area with a protective gas that is released during the melting process. Due to the presence of the flux, the melt is not only protected, but also the stable gorenje of the electric arc is maintained. By selecting the flux, specialists achieve the necessary characteristics of the weld.
The method is actively used in industrial production and is characterized by full automation: from the supply of flux to the gorenje zone to the movement of equipment along the joint. The technology is used in the manufacture of marine hulls, aircraft fuselages, locomotives and wagons, tower cranes, satellite modules and many other equipment. The output is a very high-quality weld that can easily withstand the most difficult operating conditions, including extreme temperatures and enormous pressure.
Gas-plasma
In this case, the metal of the work pieces melts under the influence of the temperature of an open flame. It is formed as a result of gorenje oxygen with combustible gases-hydrogen, propane, butane, acetylene and others. The most effective is considered to be the MAF-methylacetylene fraction. It is characterized by a high flame temperature (2927 degrees) in oxygen and, accordingly, a higher heat transfer. The compound of oxygen and MAF is inferior in toxicity to dicyan (gorenje gorenje 4500 degrees) and is less explosive compared to acetylendinitrile (gorenje gorenje 5000 degrees).
An open flame as a heat source for welding has an important advantage: it is independent of the power supply. Therefore, the technology is widely used in the "field" conditions. Another advantage is the gradual heating of the metal, which is practical when working with sheet materials. The method is unsuitable for industrial use due to the impossibility of automation and low productivity. To work with such welding, the operator requires a long experience of welding work.
Electrostatic
The edges of the parts are melted by heating the slag from the flux melted under the influence of electricity, which is previously poured between the welded elements. During the process, a wire or filler rod is used. The technology is in demand for connecting cast iron parts, less often for welding non-ferrous metals.
This type of welding is in demand in the industry for connecting large-sized parts with thick walls (40-500 mm): rotary and turbine shafts, supports, steam boilers, etc. The greater the area of the surface to be welded, the higher the economic benefit from this method of welding.
Plasma
The plasma jet that is generated in the plasma torch or between the surface of the workpieces and the electrode melts and connects the edges. The method is characterized by a large depth of processing of parts and high welding accuracy. It is in demand for connecting both small and thin-walled elements of electrical structures, and large blocks for heavy industry. Plasma effectively affects all types of metals without exception.
In addition to those considered, thermal types of welding include:
- laser
- contact butt with reflow
- electro-beam
- with embedded heaters.
Thermomechanical welding class
Contact welding: the method is characterized by simultaneous heating of the edges of the connected workpieces and their deformation under pressure. Spot welding: performed with the help of special devices or small-sized pliers. Both parts are fixed between the anode and the cathode, through which current is passed. As a result, the blanks are heated in a specific place. After heating, the current supply stops and the pressure of the electrodes increases at the place of temperature exposure. The local melt gradually crystallizes and as a result, a strong point connection is obtained.
Spot welding can be:
one-sided – both electrodes are located on the same side of the work pieces;
double-sided-the electrodes are placed on different sides of the work pieces, one opposite the other.
The disadvantages of welding experts include the fact that welding of workpieces is possible only overlapping. It is characterized by high productivity and the possibility of automation.
Spot welding is widely used in the automotive industry: conveyors around the world use this type of connection of body elements. Spot welding pliers are compact and mobile. They are used in small workshops and at home. However, they are also in demand at large service stations for performing various kinds of bodywork.
The thermostatically type also includes relief and butt welding. All other types of thermostatically welding have not become popular and have not become widespread. This:
diffuse-the connection of in homogeneous metals in a vacuum or in a protective gas environment;
forging – metals are combined as a result of plastic deformation;
due to the high-frequency current;
by friction.
Having determined the features of the welding process, the specialist will easily be able to choose a suitable welding machine taking into account its technical indicators. Most welding processes are easily automated, make it possible to form a reliable and aesthetic welding seam, are characterized by low cost and low time costs.
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