What is electric arc welding

Electric arc welding: the essence of the technology, how it is carried out, where it is used, features

Welding operations involve not only joining parts, materials or structures, but also cutting them.

This can be observed in small repair shops, work on the construction of a private house or country house, where the installation of a bulky guillotine is not provided.

In these cases, you cannot do without using a conventional holder with an electrode.

General information

Electric arc welding is one of the methods of joining metals, which is determined by the use of an electric arc.

The latter heats the metal to a temperature of more than 7,000° C, which explains the melting of its prepared ends and the formation of a weld. This method is suitable for most types of metal.

Electric arc welding technology has the following types:

• manual;
• semi-automatic;
• automatic.

The first type of connection speaks for itself. The welder holds a holder with a conductive rod in his hands, directs it to the welding area, and forms a welding bead himself, while visually controlling the process.

Semi-automatic electric arc welding differs from manual welding only in that the electrode replaces the filler rod or thread, which is fed into the weld pool area from the hopper by an automatic device.

However, control over the process is also carried out independently. Automatic is due to the complete absence of manual labor. The feeding of the rod, the movement of the electric arc, and control of the process are performed by an automated unit.

Welding technology

The electric arc welding technique is expressed by the following actions:

• the welding unit is connected to the electrical network;
• during conventional welding, plus (+) is supplied to the electrode, minus (-) to the terminal, straight polarity implies a change in the direction of the current;
• the end of the electrically conductive rod is tapped on the material being processed, which excites the welding arc;
• it is formed between the rod and the working part;
• the arc instantly transfers heat to the metal, as a result of which its edges and the electrode itself melt;
• the process forms a weld pool in which the metal of the rod and the part itself is mixed;
• after cooling, a permanent, integral connection is formed.

Electric arc welding can be performed with non-consumable or consumable electrodes using filler rods or wire.

For normal manual operations, melting rods are more often used; for semi-automatic operations, melting or non-melting rods are used.

Beginner welders who are not yet able to maintain a stable arc are recommended to use special electrodes or filler thread in the process.

Their composition is determined by the content of sodium, potassium or calcium, which stabilize the arc with their ionizing factors.

The use of active or inert protective gas - a controlled atmospheric environment - will help improve the quality of the seam. This is argon or carbon dioxide, less often helium, nitrogen, hydrogen.

Used to limit the access of oxygen from the ambient air to the weld pool. Otherwise, oxidation of the working metal occurs, which negatively affects the welding bead.

Electric arc welding is carried out using direct or alternating current—usually the former, with direct or reverse polarity, depending on the nature of the operation. Direct current produces less splashes and is characterized by a high-quality seam.

cutting

Cutting sheets of metal and parts into pieces using a welding machine is as easy as joining them.

The manual method of electric arc cutting is accompanied by the use of a consumable or non-consumable electrically conductive rod, air or oxygen-arc cutting.

Non-consumable electrode

Electric arc cutting with a non-consumable electrically conductive rod is carried out using a graphite or carbon electrode and any kind of current, but preferably constant. However, the operation is determined only by straight polarity.

The strength of the electric discharge should not exceed 800 A. The metal being cut is first heated by an arc and then melted into pieces. Coal has some advantage over metal - it melts more slowly than the latter.

Coal materials heat up faster even at low current levels. Their melting point starts above 3,000° C, which makes material consumption economical.

However, the technique is rarely used. Non-consumable electrodes are characterized by the formation of uneven edges, which suggests their use when dismantling old metal structures, cutting scrap, where aesthetically beautiful edges are not required.

The compensating quality of this type is the possible cutting of all types of metal - ferrous and non-ferrous.

melting

The operation using a consumable electrode is the most common, due to the obtainment of an even and neat cut. The procedure algorithm is expressed in the following steps:

1. Increase the current strength by a third than when welding.
2. You can navigate by the thickness of the electrically conductive rod. For a diameter of 1 mm, no more than 50 A is set, for 2 mm - 100. Each additional millimeter is accompanied by the next 50 A.
3. The working element is heated by deep penetration, which is called the support method.
4. The arc is ignited by tapping the end of the rod on the surface of the part or by striking it.

This method is used to cut most metals.

For electric arc cutting at home, garage, or cottage, it is recommended to use any melting rods - carbon, graphite. However, using special cutting tools will improve the expected result.

The latter are covered with a special coating, which improves and speeds up the process.

Air oxygen-arc operation

The types of cutting described are somewhat different from the usual ones. In air arc welding, the material is first melted by the temperature of the electric arc, and only then blown out with compressed air.

Oxygen is caused by the use of compressed oxygen instead of air flow. Both techniques require straight polarity and constant current.

Used in cutting carbon steels, the electrode is a steel tube with an outer diameter of up to 10 mm, 3.5-4 meters long. The coating applied to the tube helps to obtain a stable arc.

Similar methods are good for working with stainless steel sheets and structures. However, their thickness should not be more than 20 mm. This technique is indispensable for removing defective areas in parts.

The cutting operation is carried out using direct current, graphite or tubular rods. The latter are a special tube filled with oxygen.

During melting, oxygen is released from it, which oxidizes and blows the metal away from the part, thereby forming a cut.

Air arc is used for trimming profits after casting, removing inconsistencies of welding beads. The disadvantage of this method is the carburization of the surface of the working layer.

The procedure requires experience due to the unstable behavior of the electrical discharge and high oxygen consumption.

Advantages and disadvantages

The main advantage of the electric arc procedure is the simplicity of the operation. To carry it out, no special equipment or highly qualified welder is required.

The safe way it is carried out is also an added advantage. The disadvantage should be considered not only the lack of skills, but also the low speed of operation when processing thick sheets.

The edges of material cut in this way will look sloppy when performing precision work.

Source: https://prosvarku.info/tehnika-svarki/ehlektrodugovaya-svarka

Electric arc welding - types, methods, technology

Welding, which uses a lit electric arc, is the most common method of joining metals. Electric arc welding, characterized by its exceptional versatility, is successfully used almost everywhere today.

Electric Arc Welding Process

What is the electric arc welding method?

Electric arc welding is performed with the obligatory use of a high current source, which at the same time has a low voltage. This voltage is simultaneously applied to both the welding electrode (one contact) and the workpiece being welded (second contact).

As a result of the interaction between the workpiece and the electrode, an electric arc is formed between them, and it is due to this that the edges of the parts being connected are melted.

The use of such an arc, which is necessary to convert the energy of electric current into heat, makes it possible to obtain a temperature of about 5000 degrees in the electric arc welding zone, which is quite enough to melt any of the metals known to mankind.

Electric arc welding technology involves the simultaneous melting of the metal of the electrode and the parts being connected, due to which the so-called weld pool is formed. It is in this pool that all processes characteristic of welding take place: the metal of the electrode interacts with the metal of the parts being joined, slag is formed, which rises to the surface of the molten weld pool and forms a protective film.

Electric arc welding can be performed with two types of electrodes:

• not melting during the process of obtaining a welded joint;
• melting.

Electrodes for manual arc welding

When a non-consumable electrode is used for electric arc welding, a special filler wire is used to form the weld and is inserted into the area of ​​the electric arc. When using consumable-type electrodes, which themselves form the weld, there is no need for filler wire.

To ensure that electric arc welding is highly stable and the arc does not go out, special additives are added to the consumable electrodes. This may be sodium, potassium or other elements with a good degree of ionization. Various gases can be used to protect the weld from oxidation:

• argon;
• carbon dioxide;
• helium.

To perform electric arc welding using such gases, it is necessary to use welding machines, the design of which includes special heads. Through the latter, protective gas is supplied.

To perform welding with the formation of an electric arc, both direct and alternating current can be used. In most cases, the use of direct current is preferable, since it makes it possible to minimize the degree of spattering of the molten metal.

Electric arc characteristics

An electric arc, which is formed using a welding machine, is, in fact, an electrical discharge flowing in a gas environment. The electric current that moves in it receives this opportunity due to the presence of an electric field in it. For the purpose of streamlining terminology, such an arc is usually called a welding arc.

The welding arc, which is the main element of the formed electrical circuit, is characterized by a decrease in voltage. If the welding electrode is connected to the positive terminal of the welding machine, it is called an anode, if it is connected to the negative terminal, it is called a cathode. When performing electric arc welding using alternating current, the cathodes and anodes alternate places.

The most important parameter of the welding arc is the distance between the interacting electrodes. Such a gap through which electric current flows is called an arc. The flow of electric current through such a gap is possible only if it contains charged particles - electrons and ions. Initially, naturally, such particles do not exist in this interval. For them to appear, the ionization process must be started.

Ionization of the arc gap occurs as follows: electrons begin to be emitted from the surface of the cathode, which charge the vapors and gases formed above the weld pool. The welding arc is:

• compressed type (its cross-section can be changed using the nozzle of the welding machine, the magnitude of the electromagnetic field, and gas flow parameters);
• free (it is also called a direct arc - the parameters of an arc of this type are not adjustable, they are unchanged).

Types and methods of electric arc welding

Today, several electric arc welding methods are successfully used, the choice of which depends on the metals from which the parts being joined are made. The most common method used to join products made of both ferrous and non-ferrous metals is manual electric arc welding, which requires protection of the welding area.

Welding using this method is performed as follows. The end of the electrode, which is connected to the electrical holder, begins to heat up when it touches the parts to be connected. It is at this moment that the electrical circuit closes. After the end of the electrode has heated up, it is carefully removed from the surface of the parts to a distance of about 5 mm. The flow of electric current after such a tap is carried out through the body of the ignited arc.

Arc welding of a pipe with a consumable electrode

To increase the stability of the arc, protect both the arc and the zone of molten metal from negative external factors, add special deoxidizers to the weld metal to make it cleaner, use a special coating applied to the metal electrode rod.

Almost the same scheme is used to perform electric arc welding under a layer of protective flux, for which special welding machines, mainly automatic, are used.

In this method, the role of the electrode is performed by welding wire, which is automatically fed from a special reel. When using this technology, it is possible to weld thick products at high speed.

Of course, these products must be carefully prepared for the welding process, which requires a lot of time and effort.

Electric arc welding, which is performed with a non-consumable electrode made of tungsten, has become widespread. This type of welding is done in a shielding gas environment, which is supplied through the nozzle of the welding machine. Carbon dioxide, helium or argon are used here. This technology is used to connect parts made of stainless steel, nickel or aluminum alloys.

Inverter arc welding machine

For electric arc welding using shielding gases, consumable electrode wire can also be used. Such wire is fed into the welding zone from a special coil. The shielding gas is supplied through the same nozzle through which the welding wire is supplied. The great advantage of this technology (which belongs to the gas-electric category) is the ability to adjust the parameters of the welding arc by slightly changing the composition of the protective gas mixture.

Using this gas-electric technology, it is possible to connect metals that are highly chemically reactive (copper, stainless steel, magnesium, etc.). Several of the most significant advantages of this technology should be noted:

• the ability to easily perform electric arc welding of parts located in different spatial positions;
• good overview of the welding area;
• the ability to perform electric arc welding at high speed;
• high cleanliness of welding seams;
• ability to weld both very thick and very thin parts.

Electric arc welding can be performed using an electrode that has a tubular cross-section. The materials for the manufacture of such electrodes are flux-cored wire and a mixture of fluxes, which form a protective layer of the weld pool. The filler material for electric arc welding using this technology is the electrode itself.

Source: http://met-all.org/obrabotka/svarka/elektrodugovaya-svarka-vidy-metody-tehnologiya.html

Electric arc welding: what is it, brands and shelf life of electrodes for manual welding

Electric arc welding is one of the most common and popular methods of performing welding work using an electric arc.

This type of welding is widely used in various industries related to casting, stamping and rolling parts of product blanks. Due to its low cost, this method has almost universally replaced more expensive and complex methods of joining parts.

Types of electrodes for manual arc welding

This type of welding is carried out using direct and alternating current. Working with direct current requires the use of rectifiers or special converters.

For alternating current, welding transformers of a special design are used. The most common method is using a melting rod in an arc. It allows you to work with alloy and carbon steels, cast irons and some non-ferrous metals.

In the first case, seams are formed as a result of melting of the electrode. In the second, the filler material introduced into the weld pool melts.

There are several criteria for separating electrodes:

• thickness;
• quality;
• type of coverage.

In addition, they can be metallic or non-metallic. The second type includes only non-melting ones.

Purpose of the electrode

Table of types of electrodes for welding.

By purpose, electrodes are divided into:

• working with steels with high levels of alloying elements;
• with an average content of alloying elements;
• welding of structural steels;
• ductile metals;
• surfacing;
• heat-resistant steels.

Thus, it is possible to select electrodes for each specific task.

Special attention should be paid to the protective coating. Coating of electrodes is an important component that has special requirements. In addition, it is characterized by a certain composition.

They are a rod covered with a special shell. The power depends on what diameter it has.

The most popular are UOSI electrodes. There are several brands of this material and all of them are used for manual welding.

UONI 13-45 allows you to obtain seams of acceptable viscosity and ductility. They are used for welding during casting and forging. These rods contain nickel and molybdenum.

UONI 13-65 are suitable for work on structures with increased requirements. They can make connections in any position. The diameter varies from two to five millimeters; the larger it is, the greater the welding current.

In most characteristics, these rods are similar to each other. They can function at low temperatures, while providing a reliable tight seam with high mechanical parameters.

In addition, the compounds obtained with their help are characterized by high impact strength and cracks do not form in them. All this makes them the most promising for working with critical structures that are subject to stringent requirements.

In addition, these structures are resistant to temperature changes, vibrations and loads. An important feature of rods of this type is significant resistance to moisture and the possibility of long-term calcination.

Types of coating

Electrode coatings include the following components:

• deoxidizers;
• components for stable arc burning;
• elements that provide plasticity, such as kaolin or mica;
• aluminum, silicon;
• binders.

All coated electrodes for spot or manual welding are subject to a number of requirements:

• high efficiency;
• the ability to obtain results with the required composition;
• minor toxicity;
• reliable seam;
• stable arc burning;
• coating strength.

Types of electrode coating.

The following types of electrode coatings are distinguished:

• cellulose;
• sour;
• rutile;
• basic.

The first type allows you to perform work in all spatial positions with direct and alternating current. They are most widely used in installation. They are characterized by significant losses due to splashing and do not allow overheating.

Rutile and sour allow you to cook in all positions except vertical, with direct and alternating current. The second type of coating is not suitable for working with steels with high sulfur and carbon content.

The types of shells listed above imply the use of only one specific type of coating. However, combinations of several options are possible. Combinations can consist of several types depending on the problem being solved.

Combined shells belong to a separate class and are not classified among the main four types.

There is also a classification depending on the thickness of the coating.

Each thickness is assigned a separate letter designation:

• thin - M;
• medium thickness - C;
• thick - D;
• especially thick G.

Of course, the rods are selected in accordance with the goals set. The right choice guarantees high quality of work performed.

Electrode brands

Decoding the electrode markings.

There are different brands of electrodes designed to solve specific problems. They are characterized by certain properties, which allows you to select the most suitable material.

Grade OK-92.35 is characterized by an elongation of sixteen percent and a yield and strength strength of 514 MPa and 250 HB, respectively. The yield strength of OK-92.86 is 409 MPa.

Electrode grades for manual welding OK-92.05 and OK-92.26 have a relative elongation of 29% and 39%, and a yield strength of 319 and 419 MPa, respectively.

The yield strength of OK-92.58 is 374 MPa.

All of the above electrodes are used for manual arc welding on cast iron. Depending on what metal is to be worked with, a special type of rod is also selected. For example, for copper - ANTs/OZM2, pure nickel - OZL-32, aluminum - OZA1, monel - V56U, silumin - OZANA2, etc.

In addition, the welder also needs to control the quality of the parts being welded. Depending on the material, operating conditions, position of the seam and other factors, select the appropriate electrode that will ensure the best quality of connection.

What else is important to know about electrodes?

Electric arc welding is one of the most common methods of joining parts. It is based on the use of an electric arc, which locally melts the product.

Scheme of surfacing with different types of electrodes.

This method requires a high-current power source with low voltage. The part to be welded and the rod are attached to the device. Due to the electric arc discharge, the edges melt, as a result of which parts of the structure can be connected.

It is worth noting that the arcing temperature can exceed five thousand degrees. This value is significantly higher than the melting point of any metal known to man.

As follows from the basic operating principle of this method, when the arc is ignited, all the moisture in the rod can boil. This will lead to the formation of defects in the weld pool, as well as damage to the coating. As a result, the electrode itself may fail or it will not be able to provide high quality seams.

In connection with the above, the shelf life of electrodes can be significantly increased if stored correctly. If moisture does get on the shell, they can be dried or calcined, but if the surface is crumbled, then it is better not to use them.

The shelf life will increase if the electrodes are stored in specialized equipment that isolates them from environmental influences.

Many people are interested in the question: how to choose an electrode for welding? The selection should be made in accordance with the materials to be welded. It is necessary that the core is similar in composition to the part.

At the same time, when planning welded structures, one cannot focus solely on the performance characteristics of the metal. It is also necessary to evaluate and check the welding properties of the material.

This will make it possible to determine the thermal conditions for connecting products, as well as evaluate the possibility of using welding.

The main factor influencing the formation of cracks in steels is their composition. However, there are other properties that you should pay attention to. The fact is that depending on the type of structure, the conditions of welding work can be different, even if we are talking about the same brand.

If you have to work with materials with special properties, when the connection must have the same characteristics as the base material, the rods are selected in a special way. They must ensure the same composition of the deposited metal as that of the welded metal.

Sometimes the electrode cannot provide the required concentration of alloying elements in the weld. In this case, filler material with the missing components is used.

The concentration in the wire is set separately, depending on the technical characteristics of the connection.

Electrode position during welding.

The properties of the seam must satisfy the relevant GOST. If dissimilar steels are to be welded, the electrode is selected depending on the operating conditions.

For example, it is advisable to use EA-type electrodes for forming seams that may be exposed to aggressive environments.

It is important that the composition of the connection in this case is close to the composition of the parts of the structure being welded, which has special properties and characteristics.

An important factor when choosing a material is the type of equipment. It can implement various types of design for bringing together rods, which may not satisfy every task.

In addition, it is necessary to pay attention to the characteristics and brand of the electrode. Each material has its own optimal rod.

Table of rod grades and areas of use for manual arc welding and surfacing of alloy steel

Most rods are specifically designed to work with certain types of materials. These include alloy steels. They are widely used in industry, so appropriate consumables have been created for them.

They contain the same elements as steel to compensate during operation. Thus, electric arc welding will be most effective.

Rod type	steel grade
E-70	Kh2GMR, 14 KhMNDFR, 14 KhGNMD
NIAT 3M	30 KhGSA, 30 KhGSA, 25 KhGSA, 20 KhGSA
SSSI 13/85	35 GS, 30 HG2S, 25 G2S
OZS-11	2 МХ, 12 ХМФ, 15 Х1М1Ф, 15 ХМ
TMLZU	2 Х1МФ, 20 ХМФЛ, 15 Х1М1ФЛ, 15 Х1М1Ф
TsL-45	15 X1MF, 12 X1MF

Brands of rods and areas of application for RDS welding and surfacing of cast iron

The following grades are used for welding and surfacing of cast iron: OK-92.05, OK-92.18, OK-92. 26, OK-92.35, OK-92.58, OK-92.86.

Their characteristics were given in the section above.

Table of electrode grades and areas of use for RDS and surfacing of non-ferrous metals

Types of electrodes and their purpose:

Rod type	What metal is it for?
OZA1	Aluminum
OZA2	Silumins
OZANA1	Technical aluminum products
OZANA2	Silumins
Komsomolets 100	Technically pure copper
ANC/OZM2
ANC/OZM3
ANC/OZM4
OZL-32	Nickel
V56U	Monel welding

Table of rods for cutting metal

Types of electrodes for cutting:

Rod type	Purpose
OZR1	Cutting, forming holes, eliminating seams with defects.
OZR2	Cutting, forming holes, eliminating connections with defects.
ANR2M	Cutting, forming holes, eliminating connections with defects.

Bottom line

Electric arc welding is a common method of joining metal parts. The relative cheapness of this method and its simplicity have made it one of the most popular methods in production. Thanks to this, it has practically replaced other types of welding.

At the same time, it is necessary to pay due attention to the operating conditions of the rods. To do this, it is necessary to ensure that the electrodes are properly stored and protected from moisture.

Source: https://tutsvarka.ru/vidy/elektrodugovaya-svarka

Basic principles of electric arc welding

Electric arc welding is one of the most common types of welding in everyday life, small-scale production and industry. It can also be called fusion arc welding.

It is useful for every novice welder to know the basics of arc welding - the principle of its operation, the conditions that are necessary for the occurrence of a high-temperature arc, the types of welding machines for domestic use, and some individual parameters and features of the process.

Basic physical principle

Electric arc welding is based on not one, but two electrical principles: the phenomenon of short circuit, with which everyone who has a set of school knowledge in electricity is familiar, and the phenomenon of breakdown. This is where you should pay attention.

This refers to the breakdown of a dielectric, which occurs as a result of saturation of its interatomic space with particles carrying an electric charge. The positive charge is carried by ions, the negative charge by electrons.

Theoretically, breakdown is possible for any dielectric (under certain conditions), but in the case of electric arc welding, breakdown of the air space between the electrode and the mass (part) is specifically used.

The technological process involves creating a low-voltage, but high-power current charge on the electrode - about 80-200 A, and a huge density - up to several thousand A/cm2.

When the electrode touches a mass, that is, another material with high electrical conductivity, in the case of metal welding, a short circuit occurs, initiating a powerful electric field.

The breakdown occurs in this field. Due to saturation with charged particles, the air layer turns from a dielectric into a current conductor.

It is at this moment that the welding arc occurs, giving the name to electric arc welding. The temperature in the area of ​​contact between the arc and the metal can reach 5000 °C.

Welding arc areas

The arc completes the circuit between the electrode and ground. From the point of view of welding theory, there are several areas in the welding arc:

• cathode;
• anode;
• near-electrode.

The cathode is a “minus”, a source of current (recall that current is formed by moving electrons - negative particles). The anode is accordingly “plus”.

The anode region releases ions as a result of bombardment by a stream of electrons, therefore a so-called crater always forms on the anode - a concave spot, the area of ​​which depends on the area of ​​electron bombardment.

DC electric arc units have a fixed anode and cathode. In alternating current devices, the anode and cathode constantly change places. This causes instability of the welding arc, severe spattering of metal and other unpleasant factors, and in addition, it does not allow welding of certain metals that require special equipment.

Types of devices and types of inclusions

The simplest type of welding machine for electric arc welding is a transformer one. In essence, it is a transformer that lowers the voltage and increases the current. This device cooks with alternating current.

The process has a number of disadvantages described above; in addition, the transformer apparatus for converting industrial frequency current is very bulky and heavy.

Therefore, where mobility is required, welding inverters are most often used. These devices first convert alternating current from a household network into high-frequency current, and then convert it into direct current - rectify it. These devices have significantly smaller dimensions and weight.

Electric arc welding with an inverter allows, firstly, to achieve high arc stability, which means better quality of the seam, and secondly, to use different connection modes - with direct and reverse polarity.

The polarity is straight, when the electrode is connected to the cathode, and the ground is connected to the anode, that is, welding proceeds “from plus to minus”. This type of electric arc welding joins most metals.

But in some individual cases, for example, for welding corrosion-resistant (stainless) steels and some other chemically active metals, reverse polarity can be used - the electrode to the anode, and the mass to the cathode.

Work with reverse polarity, as a rule, occurs under flux, which forms a protective gas environment, and with filler wire.

Electrodes and shielding gases

There are quite a few types of electric arc welding, differing in the materials used, but the basic difference is one: the type of electrode. The classification here is as follows. Welding can be a consumable electrode and an electrode that does not melt during operation (non-consumable). What does it mean?

An electrode is a metal contact, a rod with a shell made of a special composition. When burned, this shell forms a protective gas environment, protecting the melt from oxidation.

But at the same time, the consumable electrode is also an additive; its base metal is part of the welded joint. Electric arc welding with a non-consumable electrode requires the introduction of additional filler wire into the weld pool (directly at the point where the reaction occurs).

There are many types of metal and non-metallic electrodes for arc welding, including carbon and graphite.

Each of them is selected for a specific metal and welding method. In addition, in certain cases, gas shielded welding is used (mainly for reactive metals). Helium, argon and carbon dioxide can be used as gases.

All these methods dictate their own approaches to the actual methodology of work. Types of welding machines and types of burners may vary. For example, in a semi-automatic device for electric arc welding in a protective environment, both shielding gas and an additive are supplied through the torch nozzle.

Various auxiliary materials, such as fluxes, can be used, so it is quite difficult to describe a universal method for creating a seam. But, nevertheless, some basic principles are present.

How to learn

The easiest way to master electric arc welding is to start with a household inverter connected to a 220 V network. After you learn how to weld correctly at home, you can move on to learning more complex technologies, such as, for example, argon arc welding.

In addition to the inverter you will need:

• thick clothes with long sleeves;
• welding gloves or mittens;
• mask;
• hammer;
• chisel;
• metal brush;
• a pack of universal electrodes;
• a workpiece in the form of a piece of thick metal - best of all, ordinary steel.

It is necessary to connect the electrode to the cathode (minus) of the device using a special holder. Plus, accordingly, it is necessary to submit for procurement. All that remains is to turn on the electric arc welding machine.

The electric arc is ignited by tapping or striking the mass. After the flash, it is necessary to move the electrode away from the metal by about 5 mm. An arc will form and the metal will begin to melt.

There are two ways to guide the electrode - with an acute angle away from you and towards you. The first method is more difficult, but allows you to make a shallower seam (this is necessary when working with thin metal). The second is simpler, this is the standard method of work.

When using electric arc welding, the electrode must be moved not in a straight line, but in a zigzag motion, to create a seam similar to the lines of a sewing machine. The electrode stroke should cover both sides of the sheets being joined.

First you just need to train on a piece of steel, then move on to welding sheet metal.

State standards requirements

Electric arc welding, like many fusion welding processes, has its own GOST standards, which are mandatory for any production facility. They describe the classification of metal welding, quality assessment methods, the specifics of additives and fluxes used, and much more.

In particular, GOST 11533-75 describes automatic and semi-automatic submerged arc welding, GOST 14771-76 describes gas-shielded arc welding. Welders working at the enterprise are required to know the requirements of state standards at least in their specific area.

Source: https://svaring.com/welding/vidy/elektrodugovaja-svarka

Electric arc welding: technologies, equipment

Electric arc welding is the most common method of joining different types of metals. This process is universal; it is used everywhere in production and in everyday life.

It has many positive qualities - it is simple to perform, does not require the use of expensive equipment, and even beginners in this business can carry out welding. But still, before starting work, it is recommended to study its basic principles and features.

What is electric arc welding

It is important to know what electric arc welding is. During this technological process, the adjacent areas of the two elements being welded are melted using the heat that comes from the electric arc. The weld pool moves behind the electric arc. And when it hardens, it turns into a state of a strong and permanent connection, which is also called a weld.

The technology of electric arc welding of metals has a characteristic feature. The molten metal base is capable of intense interaction with atmospheric oxygen and nitrogen.

In order to protect the weld pool, the following types of gases are usually used:

• Argon;
• Carbon dioxide;
• Helium and other inert gases.

It is worth noting! Electric arc welding can be carried out using consumable electrodes, the material of which will be included in the weld, as well as non-consumable ones. In these situations, flux additives are poured along the joint line in powder form.

Principle of electric arc welding

There are several principles in electric arc welding technology - short circuit and breakdown. It is the last indicator that deserves special attention.

In this case, the basis is the breakdown of the dielectric, which occurs when the interatomic space is filled with particles with an electric charge. Ions create positive charges, and electrons create negative charges. In some situations, breakdown is possible for any dielectric. But as for electric arc welding of metals, during it a breakdown of the air space between the electrode and the mass is used.

During welding, a current charge is created on the electrode with a low voltage, but with high strength - approximately 80-200 A. A huge density is also observed - several thousand A / m2.

At the moment the electrode touches the mass, namely another material with high electrical conductivity when welding metal structures, a short circuit may occur, which creates an electric field with high power. This is where the breakdown occurs.

Types and methods

Electric arc welding has several varieties.
Each of them has some distinctive features that affect the quality and type of welded joint. The following types of electric arc welding are distinguished:

• Manual electric arc welding. During it, only human manual power is used without mechanisms;
• Mechanized type. During the process, mechanization is used to feed wire into the welding area, and part of the work is done by manual force;
• Automatic type. Welding is carried out automatically. Special equipment independently feeds the arc, regulates its length and movement.

The technological process of electric arc welding is also divided into methods:

1. In a bun . During welding, several electrodes are bundled together, their ends are welded and installed in a holder. A larger range of currents is used and you can independently increase performance indicators.
2. Welding with a lying electrode . During this process, laying can be done with a length of 50 to 120 cm with coating in a cut joint or corner. A copper bar with a longitudinal groove is placed on it. After this, the workpiece and electrode are connected to a current source. The carbon rod ignites an arc that goes under the bar area. It moves along the joint, melts the working element and welds the edge. The result is a welded joint.
3. Welding with an inclined electrode . This method is carried out to improve productivity. During this process, the electrode is fixed in a clamp with a holder, which moves under its weight along the stand. At the moment the arc is ignited, the electrode melts and the holder falls down.

Types of devices

Typically, when carrying out electric arc welding, a simple welding machine is used - a transformer one. It works on the principle of a conventional transformer, lowering the voltage and increasing the current. This device cooks using alternating current.

However, transformer welding equipment is inconvenient and huge in size. For this reason, problems may arise with its movement. For these purposes, a special device on wheels is required.

If you need a mobile welding machine for electric arc welding, then an inverter is an excellent option. This equipment first converts alternating current from the household network into high-frequency current. And after that it converts it to permanent. In addition, devices of this type are lightweight and compact in size.

Inverter arc welding equipment helps achieve maximum arc stability. This is what has a positive effect on the quality of the seam. In addition, the device allows you to use different modes - with direct and reverse polarity.

Features of the work

Electric arc welding of cast iron and other types of metal must be carried out correctly. Compliance with all principles and rules will allow you to obtain a strong and high-quality weld.

Manual electric arc welding technology includes several features:

• At the initial stage, the workpieces are cleaned and degreased, and they can be cut. You need to attach a hot electrode to them. The end part of the electrode divides the surface area of ​​the element being welded into ions and electrons;
• In order for welding to be faster and the result to be of high quality, special elements should be applied to the surface of the welded material (electrode). It is recommended to use calcium, potassium, sodium. They accelerate the separation of metal into particles;
• The welding process can be carried out using an open or closed arc. When open, a lot of nitrogen will penetrate into the metal base, this will have a detrimental effect on the structure of the weld. To reduce this negative impact, a layer of metal must be applied to the electrodes. In industrial conditions, the best option would be to use a closed method, during which the welding zone will be protected from exposure to oxygen;
• Next, you need to install the electrode in the equipment for electric arc welding - an inverter. Using the end of the rod, you need to pass it twice along the ends of the metal components being welded - this will ignite the arc. After the welding machine is turned on, it is necessary to set the current at the required level;
• During the welding process, the electrode rests on the surface of the parts being welded and is slowly moved across the gap area. Liquid metal enters the weld pool, which, when solidified, forms a strong and even weld. The use of a special technological map will allow you to accurately calculate the power, current and duration of arc exposure;
• Welding of vertical seams is carried out using an arc. The level of the contact angle between the electrode and the surface to be welded must be straight. A slight deviation of 10 degrees is allowed;
• To prevent the deposition of liquid metal in one area, the herringbone, triangle, or multi-layer thin arc technique can be used.

Important! During electric arc welding, the welder must follow all the rules and steps. Each welding method is selected depending on the metal used and the welding conditions (in industrial or domestic conditions).

Security measures

When performing electric arc welding, the following safety precautions must be observed:

1. It is imperative to wear protective clothing and shoes made of thick material. These products can protect the body from hot metal, which can cause severe burns. The sleeves must be buttoned tightly, and gloves must be worn on the hands.
2. If you don’t have a protective uniform, you can use cotton clothing instead.
3. From bright light and sparks from hot metal, your face and eyes must be covered with a protective mask.
4. Welding work must be performed in ventilated areas.
5. Before starting work, it is recommended to prepare water or a fire extinguisher. Hot metal particles and sparks can lead to a fire, so all means to prevent it should be at hand.

Note! Safety precautions must be strictly observed. If this is not done, you may inadvertently suffer serious injuries during the welding process.

Electric arc welding is a popular technology that is excellent for welding different types of metals. The process must be carried out correctly in compliance with important principles. The work needs to be done in stages, this will allow you to develop an even and durable seam. But don’t forget about the necessary safety measures that will protect you from injury and help you do everything right.

Interesting video

Source: https://osvarka.com/vidy-i-sposoby-svarki/elektrodugovaya-svarka

Electric arc welding: video training

To connect metal structures, thermal effects on their individual parts are often used. Manual and automatic electric arc welding is one of the most popular types of work of this type.

Kinds

Electric arc metal welding (GOST 5264-80) is a process of joining metals, during which the temperature of the electric arc can reach 7000 degrees. This is a unique type of joining individual parts of structures, since any known metals can be welded in this way. After hardening, a weld is formed at the bonding site. Used for repairing car body, gas, water and other pipes, during production work, etc.

Photo - the principle of the electric arc

An electric arc melts the metal and metal electrodes, after which the liquid formed by temperature action fills the gap between the two workpieces.

Photo - gas burner

Types of electric arc welding:

1. Manual;
2. Semi-automatic;
3. Automatic.

The main difference between the processes lies in the principle of the work. With manual, all actions for joining metals are carried out with your own hands, with automatic - accordingly, exclusively with a welding machine. The semi-automatic process is combined. Here, electrodes are used to weld metals.

Photo - seam

Also, depending on the current used, the electric arc welding process can be carried out:

1. Variable;
2. Permanent. In turn, such technological welding can be of direct polarity (negative electrodes) and reverse (positive).

Depending on the required current, different equipment and connection methods can be used. Also, welders, depending on the type of technological processing, use different electrodes: consumable and non-consumable.

Melting can be used in any environment. They work by forming an arc between the metal and the electrode. Depending on the length of the parts to be joined, as welding progresses, the electrode is supplied to the joints.

Applicable to carbon steel, aluminum compound, copper compound, etc.

Photo - open arch

For small and thin connections, non-melting ones are used. They are often used for welding pipelines, refractory metals, and more. For such purposes, tungsten, graphite and carbon electrodes are used.

Electric arc welding is also classified according to the type of protection:

1. In a protective gas environment (GOST 14771-76). These are argon and carbon dioxide;
2. In the environment of slags. This is the process of applying heat to metal joints using submerged arcs or thick coated electrodes. The process is popular when soldering various large diameter pipes;
3. With combined protection. A soldering process in which modes are performed in a gas environment with thickly coated fluxes.

Photo - electrodes

Electric arc welding technology has its advantages and disadvantages. Advantages of the process:

1. Availability of welding equipment and additional elements (flux, electrodes). You can buy inverters at any electrical store. The average price is from 30 dollars for a manual inverter and from 80 for a semi-automatic one;
2. The heat affected zone has very little effect on the non-weldable areas of the metals. This is extremely important for joining pipes and thin rolled metal sheets.

Electric arc welding methods also have some disadvantages:

1. The use of special equipment is required. Electric arc welding is carried out only with special inverters and electrodes;
2. To weld stainless steel (alloy steel), aluminum, copper and other fusible metals, cleaning of the elements being joined is required. The edges are prepared before the heat treatment process and after its completion (only if the metal has completely cooled).

Photo - pipe connection

arc welding training

How is it carried out?

To properly weld metal using electric arc welding, you must strictly follow the instructions. Only under this condition will the weld be strong enough and neat.

Step-by-step instruction:

1. The edges of the workpieces are cleaned and degreased, and if necessary, they are cut. A hot electrode is attached to them. The end of the electrode divides a certain area of ​​the surface of the welded part into ions and electrons. It is in this space that an arc discharge occurs; Photo - stripping
2. In order for the welding process to occur faster and the result to be more reliable, various substances are applied to the surface of the welded fittings (electrodes). It can be calcium, potassium, sodium. They speed up the process of separating the metal into particles;
3. According to the type of welding, it can be performed with an open arc (melting by an unprotected flow of directed particles) or closed. In the open position, the metal purchases are saturated with nitrogen, which negatively affects the quality of the seam. To reduce this influence, the electrodes are coated with a layer of metal. For production, it is more profitable to use a closed method, in which the welding site is protected from oxygen; Photo - necessary tools
4. When all the preparatory processes are completed, you need to install the electrode in the inverter and run the end of the rod several times along the ends of the parts to be welded - this will light the arc. The devices are selected according to the type of work being carried out and depending on the characteristics and properties of the metals. After turning on the welding device, you need to set the current at the desired level, and while the system is warming up, put on safety equipment; Photo - protection
5. Different machines have different modes for welding, but any modern devices are made in such a way that they prevent the electrodes from sticking. Therefore, there is no need to try to keep the rod at a certain level from the surface;
6. Welding scheme: place the electrode on the surface of the parts to be welded and carefully slowly move along the gap. The bathroom will be filled with liquid metal, which, when solidified, forms a strong connection. In order to calculate the power, current and duration of the arc as accurately as possible, it is necessary to use the operational process map;
7. Vertical seams are welded with a short arc. The angle of contact between the electrode and the surface to be welded must be straight, a deviation of 10 degrees is allowed. To avoid metal deposition at one point, the herringbone, triangle, or multi-layer thin arc technique can be used. Each technique has its own characteristics, so the right method is selected depending on the needs and level of training.

Photo - vertical electric arc welding

After the repair is completed, you need to fix the plates in a certain position until the bathtub and seam completely harden.

Source: https://www.asutpp.ru/elektrodugovaya-svarka.html

Arc welding

Some readers ask the question: what is electric arc welding and how does it differ from other types of joining metal workpieces together? This technique is considered universal and is used everywhere. To firmly connect metal parts, a transformer with a high current but a low voltage is used, which is supplied simultaneously to the electrode and to the workpieces being connected.

What is this method?

Electric welding is an arc, with the help of which a sharp increase in temperature occurs up to 5 thousand degrees in the melting zone , which allows you to melt all the metals existing on the planet. The principle of electric arc welding is based on the melting of the electrode and workpieces, and the melting zone is the weld pool.

To ensure that electric arc welding runs continuously and the arc does not go out, additives are sprayed onto the electrode. Inert gases are used to protect the welding site.

The principle of electric welding is based on the formation of an arc, using direct or alternating current; the first option is more often used, because in this case the metal spattering is minimal.

Characteristics

To understand exactly what electric arc welding is, you need to know the nature of the occurrence of a discharge in a gas environment. When current with different poles is connected, an electric discharge occurs between the electrode and the metal of the product when approaching a minimum distance, which is called a welding arc.

It is this trunk that is the basis in the formed electrical circuit and is characterized by low voltage. When the wire with the electrode holder is connected to the positive contact, it is called an anode; when connected to the negative on a welding machine, it is called a cathode .

Degree of process automation

• manual welding using the electric arc method;
• semi-automatic option , when the wire and shielding gas are supplied automatically;
• Fully automated welding is performed without direct human intervention.

Air protection

• without active protection , using fusible electrodes with a stabilizing coating;
• protection using slag , flux of different thicknesses is sprayed onto the electrode;
• slag-gas protection - thick spraying of flux onto the electrode;
• welding in a hermetic chamber with a vacuum environment;
• the weld seam is protected with special foam ;
• in a gas environment, inert or active gases are used;
• combinations - gas plus flux.

Current polarity

• alternating current;
• direct current, with better performance achieved through the use of a rectifier and generator;
• pulse-arc method.

Electrode type

• melting;
• non-consumable - these electrodes are used as a conductor of current to the welding zone.

According to combustion conditions

can be closed, semi-open or open.

Advantages

Arc welding has the following advantages:

• performed in any spatial position;
• high mobility;
• little time is needed to prepare the work;
• not affected by limited access;
• low cost compared to other methods;
• a wide selection of electrodes allows you to connect metals of different chemical compositions;
• the ability to connect to household electrical networks when using an inverter;
• availability of welding machines, consumables (electrodes).

Modern equipment for electric welding work is simple and easy to transport to the desired location of work.

Flaws

As with any technique, there are small disadvantages:

• To apply a strong seam, solid welding experience is required;
• the surface of the electrodes is negatively affected by humidity, which leads to the appearance of defects, so they must be stored in a dry place;
• Efficiency and productivity are lower than other welding technologies;
• harmful working conditions for a welder.

It is impossible to join non-ferrous metals using electric arc welding - this is the prerogative of other methods, for example, laser, so scientists continue research work to improve the equipment, as well as the development of new materials that can increase productivity and quality.

Devices and connection

For many years, the main apparatus for performing manual electric welding was a transformer with a rough adjustment of performance characteristics, capable of withstanding long-term loads. It is easy to use and repair, but the only serious drawback is its bulkiness and heavy weight, so the equipment is used permanently, sometimes moving over short distances. Three-phase electrical lines are required for connection.

In specialized stores you can find welding inverters, which are much more compact than a transformer, and on board, in addition to the usual equipment, there is additional electronic equipment. Inverters cannot operate for a long time, although many models outperform older equipment in this regard.

Such devices are equipped with additional functions that simplify the work of the welder, but are sensitive to mechanical stress and do not have protection against the penetration of moisture or dust.

Repair is much more complicated, and the cost is higher than a modern analog transformer. The connection is simple - just insert the plug into the socket and the equipment is ready for use.

As for the electrode holders, they are installed in special sockets on the front panel, so each user chooses the model that is convenient and comfortable to work with.

Application area

Electric welding is widely used in any production:

• Connection of flat frames and meshes of reinforcement.
• Welding blocks during installation to create a solid structure.
• A set of meshes from pre-prepared reinforcement bars.
• Connecting elements of reinforced concrete structures.
• Preparation of reinforcement in specialized organizations for subsequent joining during the construction of bridge structures.
• Connections of reinforcement bars with diameters greater than 10 mm.

For smaller reinforcement diameters, this technology is not used due to the risk of burning through the workpieces.

Security basics

At any enterprise, welders are given special protection:

1. Clothing made of dense natural and non-flammable material - tarpaulin, split leather or suede. In winter, cloth clothes are worn underneath it.
2. Hands are protected with thick gloves or mittens, which should not restrict the movement of the hands.
3. Particular attention is paid to shoes - boots, boots made of tarpaulin with soles made of rubber or more modern materials without nails.
4. The protection of the facial area and eyes is performed by a special mask or shield, for which labor safety inspectors have high requirements, especially for tinted glass.

Requirements of state standards

The correct execution and designation in the drawing of the main types of connections of steel structural elements using manual welding is regulated by GOST 5264 - 80.

GOST 11534 - 75 is used when the workpieces form obtuse or acute angles.

A separate GOST 16037 - 80 regulates the performance of work during the construction of pipelines due to the high responsibility and special strength of welded joints.

For electrodes, GOST 9467-75 has been developed, which describes in detail the requirements for coating or spraying of electrodes, and also provides the necessary characteristics that welds must have.

conclusions

Technological progress is developing by leaps and bounds, because of this there is often a need to connect parts of different thicknesses, consisting of heterogeneous materials. Previously, steels containing carbon were used, but today alloys of both light metals and titanium are used.

Structures are becoming more complex and volumes are increasing, therefore, the pace of bridge construction, the construction of multi-storey block-type buildings and the performance of other multidisciplinary tasks directly depends on the professional training of welders - not only theoretical, but also practical.

Source: https://svarka.guru/vidy/thermo/dugovaya

Types of arc welding

Arc welding technology is divided into certain groups depending on the choice. There are several classifications that have the most recognized meaning:

• degree of mechanization of the process: mechanized or automated;
• type and polarity of current;
• type of electric arc;
• type of weld pool protection;
• type of electrodes.       

According to the degree of automation of the process:

• Manual (DGS);
• Semi-automatic: the welding wire is fed automatically and the electrode is moved manually;
• Automatic: the entire process of moving the wire and electrode is fully automated.

By types and polarities of current:

• Permanent: connects the welded surfaces with a thin seam;
• High-frequency: the electrode melts in a stream, the slots are eliminated, the clamps are welded;
• Pulse;
• Alternating: Used for cutting metal sheets.

By type of protection against exposure to air:

• Slag;
• Flux;
• Inert gas.

All types of protection are different depending on the conditions and purpose of the work. The protection protects the metal from the penetration of air into the weld pool, which forms cracks, cavities, and increases the spattering of melts.

By type of electrodes:

• Melting with sprinkling: used to create a weld pool and gluing edges;
• Non-consumable tungsten: used for spraying, restoring damaged parts, welding beads.

According to the combustion process conditions:

• Open arc. It is visible, but it should only be observed through special filters that protect the eyes. The open form is used in manual processes and in gas shield welding;
• Closed. The form is invisible.

  The arc is located in the molten metal - flux. slag;

• Half open. The arc is visible. But you can only observe one part. The first part is in the metal, the second is above it. You can look at the process through light filters.

  This type of arc is used when welding aluminum automatically.

According to the method of protecting the welding zone:

• Without protection: bare electrode, stabilizing electrode coating;
• Slag protection: submerged, with thickly coated electrodes;
• Slag and gas protection: frost-coated electrodes;
• Gas protection: in gas environments;
• Combined protection: gas environment, coating, flux.

Installation modes

Arc welding is divided into modes:

with coated electrodes – MMA mode;

For argon arc welding using non-consumable electrodes - TIG.

Both modes involve operation on direct current - DC and alternating current - AC.

Both modes provide smooth regulation of the amount of incoming current, indication of arc current, and the ability to change modes. TIG performs long and short seams, purging of the gas passage, and a smooth reduction in current. Non-contact ignition on any type of current and regulation of arc capabilities are possible. It will melt and clean surfaces. The modes are easy to set and do not change without changing the settings by the welder.

Process technology

The principle of arc welding is based on the following actions: Current flows from the inverter to the electrode. It forms an arc by creating a closed circuit between the surface to be welded and the electrode. The arc melts the electrode, creating a weld pool. The whole process is precisely and strictly regulated. It is the same for all types of manual welding:

The electrode has a metal rod coated with silicate, flux, and glass. Any layer, when burned at high temperatures, forms a gas cloud and slag emissions. They protect against the penetration of air into the working environment, which destroys the metal. During the work, a connection is formed: the electrode - the part being welded. The rod melts, moving along the place of gluing or defect, forming a seam.

Aluminum surfacing

Very often it is not necessary to weld parts, but to repair them. During operation, parts wear out, and additional metal beads need to be added to individual parts. Surfacing is required in various situations:

• Broken fastening parts;
• Appearance of attrition;
• Broken edges;
• Chips;
• Destruction of the edges of metal-cutting tools;
• Worn bearing bushings and internal surfaces.

Surfacing in welding terminology is the process of restoring lost shapes and original dimensions. Surfacing is convenient in that it can be placed on any surface, its thickness and volume can be changed, and worn-out and defective equipment can be repaired.

Welding with inverter

lessons will help you understand how to weld. The step-by-step instructions on the video will show the entire procedure in sequence. How to connect metal sheets, control the arc gap. You will see how the weld is formed and what defects may appear.

The inverter provides the ability to perform jobs that previously could only be done with heavy production equipment. The inverter is a fairly small welding machine. It is economical and easy to use. The main burden falls on electrical networks.

The required arc thickness is set on the inverter panel; it depends on the current strength. The arc is ignited and the process begins. Scale is formed, a seam is formed, and excess metal is knocked off with metal hammers. The welding seam, if done correctly, will be strong and solid. If the process is disrupted, a defective seam appears.

To obtain a perfect seam, it is recommended to make circular movements. They will form the desired thickness of the influx. The inverter allows you to maintain the desired angle of inclination, on which the quality of the resulting seam also depends:

• with recess;
• flat;
• drop-shaped;
• point;
• convex.

Polarity is taken into account. Direct - gives a reduced input of the thermal arc into the metal, the melting is narrow but deep. Reverse polarity changes the seam: it is wide but shallow.  

Application Methods for Electrical Carbon Steels

Carbon steels are divided into groups depending on the percentage of carbon in the alloys:

• High carbon – 0.6-2.07%;
• Medium carbon – 0.25-0.6%;
• Low carbon – less than 0.25%.

Depending on the group, the arc welding procedure is carried out. But there are also general approaches to the process. Butt seams in this case are often welded when the parts are in a suspended state. The equipment is aimed at ensuring that the seam is firmly welded, but without burning through the metal.

Electric arc welding allows work to be done on both sides; seams can be applied in several layers. If the parts are thick enough, then this type of work will be suitable. But the hanging of products and sheets leads to defective work.

To eliminate it, use the electric arc method again:

• The metal at the defect site is removed;
• Edges and surfaces are cleaned;
• Defective areas are re-welded.

If the electroslag method is chosen, then staples are used. They secure the parts and are then welded from above at the entry point into the metal parts. Sometimes strips are welded to close the seam using this method. They secure the seam, eliminating the possibility of tearing the structure.

Welding rectifiers

Devices that convert alternating current into direct current needed for welding are called rectifiers. They consist of the following components:

• Power transformer;
• Saturation choke;
• Voltage (current) regulator;
• Rectifier (block)
• Throttle;
• Starting devices;
• Measuring equipment;
• Protective equipment.

The rectifier converts power energy, it equalizes the required electricity parameters to obtain the desired quality of welding work. There are several schemes for constructing rectifier units; they are selected depending on the type of welding and the design of the power part of the device.

Electric welding temperature

The arc temperature reaches 7 thousand degrees. It is higher than the temperature that any of the metals can withstand. This is why the metal melts and combines with another material.

Safety precautions

Arc welding requires special attention from a person. He may be shocked by electric shock, and there is a danger of being poisoned by harmful substances released from the metal during welding work. Welding dust consists of various chemical compounds:

• manganese oxide;
• silicon;
• iron;
• chromium;
• fluorine.

The most dangerous are chromium and manganese. Air pollution occurs due to the release of carbon and hydrogen fluoride. A person may experience dizziness and headache. Poisoning will cause vomiting. Weakness will appear. With a strong impact on the body, with weak immunity, the consequence of improper work will be chronic diseases and exacerbations.

The greatest degree of contamination occurs when welding with coated electrodes. Less when automating work. The welding arc produces various radiations (color, infrared, ultraviolet). They have a negative effect on the eyes: vision weakens and is lost. The heat generated during welding can cause burns.

There are a number of safety requirements and regulations.

• Insulation. Various protective barriers are used: blocking, shields, barriers.
• Individual equipment: special clothing, mittens, shoes, galoshes, rubber helmet.
• Creation of necessary safe conditions. Do not work in strong wind, rain or snow.
• Checking the serviceability of the equipment used.
• Work only with permission (admission) or professional education.

Arc welding designation

In accordance with the GOST 2.312 - 68 standard, special symbols for drawings are established. To find or depict a seam produced by arc welding, you will need to know the symbols used in construction documentation.

The seam that is visible is drawn in the drawing as a solid line, the invisible one is drawn as a line of dashes. If it is not a seam that is welded, but only a specific point on the surface, then it is designated with a + sign. If a point is hidden from view, it is not depicted.

The solid line itself has different thicknesses: for borders, a clearer line is chosen, and for elements located inside or along the edge, a thin line is required.

To simplify the work with drawings, from each image of a seam there is an extended arrow that will indicate the technical document.

Prices

The cost of various types of welding machines ranges from 2 to 170 thousand. Depending on the purpose and scope of work, you can select equipment at the right price. The range of equipment is quite wide. When choosing, you will need to consult a specialist; only he will tell you which modification is best to choose and which device to purchase.  

Source: https://svarkagid.com/dugovaja-svarka/