Electrodes for inverter welding are selected depending on the level of deoxidation of the steel from which the product is made, the amount of carbon contained in the steel and the requirements for the weld.

Each type of welding machine requires the use of only a certain type of electrode.

How to choose consumables for welding?

Each type of welding machine requires its own type of electrodes to carry out welding, sometimes even within the same type of welding machine.

When welding different models welding devices may require different types of consumables.

The inverter is a welding machine with an electronic design. This device is equipped with an AC double conversion system. Among modern welding devices, inverters are the most promising for carrying out operations for welding any metal workpieces. For normal welding, it is necessary to correctly select the type of electrodes used.

Most often, professional welders use the following brands of consumables:

• SSSI;

Electrodes of the MR, OZS and ANO brands are more preferable, since the use of consumables of this type is more convenient. SSSI electrodes are Consumables, which have a large number of advantages, but these positive qualities are revealed only if this material is used by a professional.

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The best electrodes for working with an inverter welding machine

If you need to purchase consumables suitable for welding and choose the best ones among them, you will need to pay attention to the recommendations for operating the welding inverter of the exact model that you plan to carry out the work. As a rule, it is in the operating recommendations that the brands of electrodes that are optimally suited for the job are indicated.

It is worth noting that the choice of marking of optimally suitable consumables is not the only condition that must be observed when choosing consumables for welding. When choosing welding electrodes, you need to make sure that the consumables for welding work have their inherent qualities that have not been damaged during storage. The properties of the electrodes are preserved for a long time only if they are stored in accordance with the requirements of the manufacturer. Storage of consumables intended for welding must be carried out in accordance with the requirements of developed GOSTs.

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Welding electrodes MZ-3, electrode type E46

The scope of application of MP-3 is the connection of critical structures that are made of carbon steel. These electrodes can be used when working in any spatial position, with the exception of the vertical direction from top to bottom

The use of this consumable allows you to weld wet, rusty and poorly cleaned metal workpieces from oxidation.

Welding electrodes MP-3 are designed for welding carbon steel.

The electrodes have parameters that allow for increased productivity. The use of this type of consumables makes it possible to use an extended arc during the welding process, which makes the process easier. These electrodes are recommended for use when connecting pipelines high pressure with temperatures of transported liquids up to 3500 degrees Celsius and internal pressure up to 50 kgf\cm². In addition, these electrodes can be used when installing gas pipelines and pipelines

The advantages of this type of consumable are:

• easy bridging of gaps;
• high quality the resulting seam;
• obtaining a commercial appearance of the seam;
• easy separation of the slag component;
• possibility of working with a long arc;
• high sanitary and hygienic indicators during the process.

Electrodes of this type have a rutile-base coating of a protective layer; before using this material, it is recommended to calcinate at 170-180 degrees for 40-60 minutes.

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Welding consumables brand MP-3 blue, electrode type E 46

Blue electrodes of the MP-3 brand are intended for connecting elements made of low-carbon steel.

This type of electrodes for inverters is used for welding particularly critical products consisting of low-carbon steel. This type of electrode can be used in any spatial orientation, with the exception of a vertical position in the top-down direction. Consumables brand MR-3S are used when working with sheet and profile materials. These electrodes are widely used in the construction of ship hulls, pipelines, and critical tanks.

The advantages of MP-3S are the following properties:

• MP-3C provide the ability to easily carry out the welding process and re-ignite the arc when the process is stopped;
• high-quality appearance of the weld;
• easy slag separation;
• minimal likelihood of metal splashes;
• possibility of welding at low current values;
• MP-3S provide the possibility of electric welding using household network nutrition;
• the possibility of obtaining a concave weld seam;
• high efficiency of work.

The electrodes are coated with rutile; before using MP-3, blue ones are recommended to be calcined at a temperature of 170 degrees Celsius for 40 minutes.

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Consumables brand OZS-12

Consumables of the OZS 12 brand are used on inverters operating on direct and alternating current of direct polarity.

This type of consumables is used to create critical structures consisting of low-carbon steels. These materials allow work to be carried out in any spatial position, except vertical, from top to bottom. This type of consumables is used by welding machines operating on direct and alternating current with straight polarity.

OZS-12 is used when conducting welding operations on metal structures consisting of sheet and profile metal. OZS-12 is used in the manufacture of building structures, tanks, ship hulls and ship mechanisms, pipelines and metal structures of various cranes. The advantages of consumables brand OZS-12 are:

• possibility of obtaining flat and concave seams;
• ease of welding and re-ignition of the electric arc;
• obtaining a high-quality seam;
• easy separation of slag during welding;
• possibility of working with an extended arc.

The consumable has a rutile coating. Before use, it is recommended to calcinate OZS-12 electrodes at a temperature of 200 degrees Celsius for 30 minutes.

You can quickly and efficiently weld any, even the most complex metal structures, using inverters. These units have quickly become part of modern operational processes because they are easy to operate and produce high-quality welds that are smooth and neat. Of course, the main component of the welding process is the electrodes for welding with an inverter. Essentially, it is a metal rod that is coated with a special material called coating.

Welding electrodes are made from different steel wires that comply with GOST 2246-70. Therefore, electrodes for inverter welding are divided into several groups according to the raw material.

• Made from alloy wire. For example, from Sv-08Kh3G2SM.
• Highly alloyed - Sv-30Х15Н35В3Б3Т.
• Made of carbon - Sv-10G2.

The brands of welding wire are listed one at a time, but their list is quite wide.

As for the protective coating (coating), it is specially applied to the rod in order to protect the weld pool from exposure to oxygen on the molten metal. This one chemical element negatively affects the quality of the material, creating oxide films on its surface. This is feather. The second is arc stabilization.

The protective coating is applied to the welding rod by pressing, so the bond between the two materials is very high. The coating itself is divided into four types.

1. Main.
2. Sour.
3. Cellulose.

The first and last types are used only for welding DC. The rest are both with direct current and alternating current.

Which electrodes are best for cooking with an inverter?

Electrodes for the inverter are divided into two groups.

1. Conventional ones, which are used everywhere for any designs. These include the ANO and MR brands.
2. Consumables for critical structures. These include the SSSI brand.

All welders believe that the SSSI brand is very capricious. Not everyone can cook with these electrodes; experience and qualifications are required. Therefore, it is better for beginners to carry out welding with an inverter using conventional methods.

Electrode brands

To answer the question of how to choose electrodes, you need to understand the brands indicated above.

SSSI

Their main purpose is welding products made of carbon and low-alloy steels. As mentioned above, they are used to assemble structures that are subject to increased requirements. Particularly stringent requirements for welds, which must have increased impact strength and ductility.

Welding can be done at low temperatures. The coating is basic, the current is constant, the polarity is reversed. Rod diameter: 2-5 mm. The welding seam is of high quality, high density. Structures welded with these electrodes cope well with temperature changes, bending loads and shocks.

MR

1. MP-3. They are used to connect carbon blanks, the joint of which can withstand a resistance (temporary) of up to 490 MPa. The coating is rutile, the current is alternating or direct, the polarity is any. You can cook with an electrode in any position with a reservation. So, in the lower position, welding is carried out with electrodes with a diameter of up to 6 mm, in a vertical position up to 5 mm, in the ceiling (upper) position up to 4 mm. Using MP-3, you can cook contaminated or rusty-coated workpieces. With them, welding is carried out with increased productivity.
2. MR-3S. This is a model that is used for the same purposes as the previous one. The joint welded by it can withstand resistance up to 450 MPa. Coating – rutile-cellulose, current – ​​alternating and direct, polarity – any. Welding position – any. They can even cook wet metals.

The brand of MR consumables for beginners can be called the best electrodes. They are not capricious, they can easily tolerate the process itself, a small splash of metal, plus an excellent seam.

ANO

We must pay tribute to this brand, which all experts consider universal. ANO is the most popular brand today. If we were to choose from all the types offered by manufacturers, then this is the one.

Using these electrodes (welding for inverter), you can weld workpieces up to 5 mm thick in different positions, even vertically from top to bottom. In this case, the joining of two metals can be: butting, overlapping, angular. There are no great requirements for the cleanliness of the welded edges; welding of oxidized surfaces can be carried out. They also perform root welding of thick workpieces. The coating is rutile-cellulose. Current – ​​alternating or direct. Polarity – any.

Available in model range This type is ANO-4 grade with rutile-carbonate coating, which is used for welding critical structures.

OK 63.34

If it becomes necessary to weld two stainless steel workpieces, this can be done using an inverter, using an electrode from the Swedish manufacturer ESAB. By the way, this electrode can be used to connect structural steel products.

The seam from such a consumable is equal to the smooth transition from the base metal. In this case, slag is formed in small quantities and is easy to remove. You can weld any position of joints in metals with a thickness of 6-8 mm in root welding. Although the electrode itself was designed for welding thin stainless steel products. You can use it to connect butt and overlap joints. It is also used for multilayer welding not only in the horizontal plane, but also in the vertical.

Carbon and graphite electrodes

An important component of the welding process is the tight pressing of the edges of the workpieces to each other. This can be done with tack welding, spot welding, or mechanical devices (clamps, clamps, etc.). By the way, this technology can only be used in the down position.

Welding process

The work of a welder depends not only on the correctly selected brand of electrodes. You will have to select the correct diameter and accurately set the welding parameters on the inverter itself. This mainly concerns the current strength. In addition, it will be important to know which output (plus or minus) to connect the consumable you have chosen.

The diameter of the welding rod must be equal to the thickness of the workpiece to be welded. For example, the thickness of the parts being welded is 3 mm. This means that it is better to cook them with an electrode with a diameter of 3 mm. If you are welding thick metal, for example, 10 mm, then you can use any of the diameters, because welding in in this case will be carried out layer by layer. But even here it is better to use a thick consumable.

As for the polarity, it depends on which output the electrode is connected to: negative or positive. If to the minus, and the plus is respectively connected to the workpiece being welded, then this is direct polarity. If it's the other way around, then it's the opposite.

In what. Everyone knows that the flow of electrons (which is also an electric current) moves from minus to plus. And the element of the welding process that is connected to the positive heats up more. That is, if you change the location of the electrode relative to the connection position, you can change the intensity of its heating.

Attention! With an electrode with a diameter of 3 mm, it is better to weld metal 2 mm thick with reverse polarity. And using the same consumables, it is better to cook metal 6 mm thick with direct polarity.

Now, as for the current strength when welding with an inverter. It is usually indicated on the packaging. But you can use a simple ratio: 20-30 amperes of current per millimeter of rod diameter. Let's face it, the range is quite wide. But it will be necessary to take into account the mode of laying the weld. That is, it will be laid continuously without separation, or with separation. In the first case, the calculation takes an indicator of 20 amperes, in the second - 30. Although all these are only recommendations, because a fairly wide list of welding mode criteria must be taken into account.

• Fluidity of the base metal, its grade.
• The speed of the welder's hand.
• Electrode position during welding. For example, in the ceiling position the current is reduced.

The optimal regime will come with time and experience. Therefore, the welder must pay attention to the weld pool. It is precisely this indicator of the quality of the selected mode. The correct seam should be uniform. If a lot of metal has formed in the bathtub, it means that either the arc is too short or the welding speed was insufficient. If a saddle turned out in the bathroom, then the seam was welded too quickly, or the arc was too long. The displacement of the metal in the bathroom to one side indicates that the electrode's even, strictly axial movement was not maintained. In addition, the current strength was large.

Choosing a good option that matches the mode and metal is not always easy. A beginner cannot do this, so manufacturers give recommendations on the packaging. More or less they coincide with the actual ones. But, as mentioned above, everything will come with experience. We suggest you watch the video - which electrodes are best to choose for welding with an inverter.

A strong and reliable connection of metals depends on many factors, the main one of which is the matching of the electrode and the workpieces being welded. Before choosing electrodes for welding, you need to determine the chemical composition of the parts, as this will help you select optimal combination coated product and blanks. Also very important is the correct choice of coating, which is applied to the electrode and is also a flux with alloying additives. This coating significantly influences the welding process and its right choice when applied to specific materials, it provides the best strength and durability of the welded joint.

Welding machines and selection of consumable electrodes

When selecting a welding mode in a qualified manner, it is necessary to take into account the parameters of the welding unit, which make it possible to use the best electrodes and the most preferable conditions for fusing parts. There are several types of welding, using consumable coated products, non-consumable tungsten or semi-automatic feeding methods using wire with special properties. Welding equipment is divided into the following types:

1. AC step-down transformer or with DC rectifier circuit;
2. DC inverter device;
3. a device using an inverter, with a refractory tungsten electrode and manual feeding of welding wire into the melt zone;
4. semi-automatic unit with wire feeding into the welding seam area.

Each of the devices has technical properties in terms of current and voltage, which dictate the selection of products of the appropriate diameter and coating composition. It should be noted that the wire, which is the electrode during semi-automatic and manual feeding into the melting zone, also serves the purpose of best matching the composition of the parts being welded. The choice of electrodes depends on the method of welding with direct or reverse voltage connection, since the depth of welding is related to polarity and the selection of diameter directly depends on this.

The coating of the rod, as well as the composition of the wire, serves to implement certain tasks:

• the use of carbon oxides protects the weld pool from atmospheric oxygen;
• facilitates ignition and stabilizes the arc discharge;
• helps remove oxygen from the melt zone, deoxidizing the seam;
• with the help of impurities it has an alloying effect on the seam.

It is these requirements that serve as the determining factors for choosing good coated electrodes for specific tasks. Russian industry produces a wide range of products for welding various metals and alloys. For domestic purposes, it is necessary to choose priority materials for welding. As a rule, this is the welding of ferrous metals, cast iron, stainless steels and alloys of aluminum and copper. Sometimes they resort to welding workpieces of dissimilar composition, and here, you should choose an electrode with the closest parameters to the main composition of the parts.

Popular types of electrodes

Various types of welding products are produced, which are selected taking into account the characteristics of the materials being joined and welding methods. In the case of argon arc welding, a refractory tungsten rod is used, and wire is manually fed into the melt zone. When working with semi-automatic machines, the electrode for inverter welding is wire of different compositions fed through a torch at an adjustable speed. The most common method is the use of piece consumable electrodes, the coating thickness of which can be extra thick (G), thin (M), medium (C) and thick (D).

The choice of coating thickness by the welder creates conditions for changing the degree of exposure to the seam to protect it from the influence of atmospheric oxygen, traces of contamination and the oxide layer. Based on the composition of the coating, electrodes are divided as follows:

• the main type for welding with direct current and obtaining a plastic seam;
• type with an acid coating to ensure the ductility of the metal in the weld pool area;
• resistance to impact is imparted by a cellulose coating; these products are also used on vertical seams;
• rutile coating promotes stable arc ignition;
• special electrodes for welding copper and aluminum, as well as their alloys.

When choosing a product, you need to take into account the thickness and composition of the workpieces, welding current and electrode diameter, these parameters must be linked to the characteristics of the device. For welding steel 1 mm thick, electrodes with a diameter of 1.2 to 2 mm are selected, and a current of 45–55 A is required. For workpieces 2 mm thick, a diameter of 2.5 mm and a current of 60–80 A are required, parts from 3 up to 5 mm require the use of a diameter of 3 to 4 mm and a current of 70 to 130 A. Thicker workpieces are welded with a 5 mm electrode and a current of 210 A and higher. The most popular products, especially among beginners, include rods with rutile and basic coatings, although the choice largely depends on the composition of the material being welded.

The main coating of electrodes of the UONI brand allows for inverter welding, both in direct and reverse polarity, and the rutile grade MP-3 makes it possible to use alternating and direct currents and is characterized by easy ignition of the arc.

Metals to be welded and choice of electrodes

For high-quality welding, certain experience and knowledge are required chemical composition blanks Therefore, before choosing welding electrodes, you need to find out what kind of metal or alloy you are going to join. For different types of metals, corresponding products have been developed with different types coatings and many of them are analogues. Various reference books, advice from sales professionals or experienced specialists can help here. In most cases, they work with carbon and stainless steels, cast iron and alloys of copper and aluminum. Welding of galvanized steel, dissimilar workpieces and nickel-plated parts is quite popular. High strength and durability of the weld is achieved by precise selection of the material of the consumable electrode and its coating to the metal or alloy being connected and consists of the following recommendations:

• structural low-alloy, carbon steels are very well welded using grades MR-3M, UONI-13/55, OMA-2, OZS-30, VI-10-6, ANO-21 and VSF-65U;
• high-strength alloy steels are welded using EA-981/5, EA-395/9, NIAT-5, OSHZ-1 and NIAT-3M;
• heat-resistant alloys and heat-resistant steel are combined with grades TsL-39, ANZHR-2, TML-3U, OZL-35, IMET-10 and KTI-7A;
• electrodes IZH-15S, NIAT-1, UONI-13NZH, TsT-15 and EA-400/10T are suitable for corrosion-resistant and stainless materials;
• parts made from materials of dissimilar composition are welded using grades ANZHR-2, EA-391/15, VI-IM-1, TsT-28, OZL-32, NII-48G, IMET-10, V-56U and;
• for special steels, grades OZL-44, ANV-20, EA-112/15 and NII-48G are used;
• for cast iron blanks, TsCh-4, OZZHN-1, OZCh-2 and MNCh-2 are used;
• aluminum alloys are welded using OZA-1, OZA-2, OZANA-1, OZANA-2;
• copper and its compounds are boiled using ANTs/OZM-2, OZB-3, Komsomolets-100; OZB-2M is suitable for bronze;
• OZL-32 and V-56U are suitable for nickel alloys;
• for cutting metal they use the ANR-2M, OZR-2 and OZR-1 grades.

When welding thin-walled sheets, it is sometimes necessary to reverse the polarity in order to reduce the penetration depth and eliminate the risk of burning through the workpieces. In this case, they resort to inverter welding with high-frequency, pulsed alternating current.

Bottom line

We talked about the basic principles for selecting coated electrodes for welding using various devices. When selecting a brand, it is necessary to take into account the type of coating and the diameter of the rods, the current strength and the composition of the parts. With the acquisition of some experience and skills, effective work will not be difficult.

Sergey Odintsov

electrod.biz

How to choose electrodes for welding

When the task is to buy electrodes, of course, it is better to understand this issue thoroughly: what types of metal are there, how they differ, what metals they are intended for, as well as what types and brands of electrodes there are.

Now, in order to start practicing making seams as quickly as possible, a simpler choice will be considered.

As for choosing a store, it is preferable to buy in a specialized store that sells welding equipment and consumables, rather than in a regular hardware store, because in a specialized store, most likely, the sellers understand this topic and will be able to suggest something.

Where everything is sold, most likely, the sellers do not have proper competence in the selection of welding electrodes. In addition, it often happens that prices are higher in regular hardware stores. Perhaps it is implied that a person who buys such materials in a non-specialized store does not understand the issue enough to have a good idea of ​​how much they cost.

Arriving at a specialized store, it is enough to say that you need electrodes for welding carbon steel of ordinary quality, or ordinary carbon steel. Each type of electrode can have several brands. For example, Table 5 with electrodes of type E46 is shown.

Type	Brand
E46	MP3C; ANO-21, ANO-4; OZS-4, OZS-6, OZS-12, etc.

Sometimes the marking is marked with the letter “A” - for example, E46A. This means increased ductility of the weld. Since type E46 is taken as an example, further explanation of the principles of selection will take place using the example of the same type of electrodes. There is a wide range of electrodes of the ANO brand (21, 36, 4, etc.), OZS, MR-3.

It is unlikely that the store will have the entire “line” of a certain label. Most likely there will be one or two options. It makes sense to buy the smallest portion that they can offer and try which electrodes will produce the highest quality seams in this particular situation.

It also makes sense to try welding with UONI 13/55 electrodes, this is type E50. It differs from the E46 type; in some situations, with their help it will be possible to obtain a better weld.

In any case, you first need to try: buy a small batch, and then, if you get a high-quality result, you can take the required quantity for the entire volume of welding work.

Working principle of the electrode

The figure shows a diagram of the manual arc welding (MAW) process.

An electrode is a metal rod on which a coating or coating is applied.

As a result of the burning of the arc 3 and under the influence of its temperature, the metal rod 5 melts, and the metal from this rod is transferred to the weld pool 2. The coating also melts due to the high temperature. As a result of its melting, they form protective gases that protect the arc and weld pool from the effects of oxygen, nitrogen and other gases contained in the air. In addition, the resulting gases help stabilize the arc.

During the melting of the coating, liquid slag is formed, which spreads over the surface of the weld pool. At the same time, liquid slag deoxidizes the metal, ridding the weld pool of oxygen, and, conversely, adds alloying additives to improve the quality of the weld metal and the welded joint as a whole. As the weld cools, the liquid slag turns into a slag crust 10, which must subsequently be removed.

• What electrode diameter is suitable for a particular metal thickness;
• What welding current to set to obtain a high-quality seam.
• Difference between welding modes: direct polarity and reverse polarity

Electrode diameters

Measured in millimeters, these values ​​are standard and according to Russian GOST they are: 1.6; 2; 2.5; 3; 4; 5; 6, etc. Imported ones also have other diameters, for example 2.6 instead of 2.5; 3.2 instead of 3. Diameters larger than 4 mm are not of interest for household welding work, because the household electrical network does not produce such power that would allow the use of electrodes with a diameter of 5-6 mm or more.

Even with a diameter of 4 mm it is often impossible to use, since welding machines usually do not produce the required welding current, and some Electricity of the net, especially outside the city, they do not allow you to cook with such electrodes.

The diameter of the electrode, indicated in millimeters, means the diameter of the metal rod, that is, without taking into account the thickness of the coating. Typically, the larger it is, the longer it is.

Defects

The coating must be applied to the electrode evenly along the entire length and circumference. If the coating is uneven in thickness, that is, somewhere thicker and somewhere thinner, this is a defect. When the coating is applied evenly along the length, but is thicker on one side and thinner on the other, this is also a defect. In such cases, it is more difficult to obtain a high-quality seam.

The coating should not crumble or fall off. If the coating has fallen off at the end of the electrode, lighting the arc will be much more difficult. In addition to cases of manufacturing defects, the coating can also crumble when the electrode is old or has not been stored properly. One way or another, working with such a rod will be very difficult, or even impossible.

Electrode ends

In this embodiment, the metal rod is covered with slag, and when trying to strike an arc, there will be no electrical contact between the metal rod and the metal of the part, and the arc will not burn. It is necessary to hit the hard dielectric surface hard enough to dislodge the slag.

The electrode coating is covered with slag

Important: you can hit any hard dielectric surface with an electrode. It is acceptable to hit the part being welded, but in this case you need to make sure that there is no operating voltage on it!

If metal is visible at the end of the electrode, then igniting the arc will not cause problems. In the photo below the situation is the opposite. The coating fell off. In this case, it will be difficult to ignite the electrode for another reason.

The coating performs the function of protecting the arc, stabilizing the burning of the arc - roughly speaking, “helps the arc burn.” If there is no coating, the arc will either not burn at all, or will burn very unstable, and good welding will not work. The problem is solved by biting off this part of the electrode.

The electrode coating has fallen off

There is another option for more experienced welders - to “strike” the electrode, barely touching the metal and preventing the electrode from sticking to the part. To do this you need to apply minimum effort in the vertical direction and sufficient force in the direction of movement of the electrode parallel to the part, without holding the electrode in one place. Perform the required number of movements in this way until the metal rod burns.

Remaining electrode

When making a weld, the electrode burns out and the question arises to what minimum length to use it. In other words, how long should the cinder remain.

In principle, the optimal length is 3 cm, but this figure may vary. For example, if there are 4 cm left and you need to make the next relatively long seam, then there is no point in burning out this centimeter. It's better to get a new one right away.

It is undesirable to burn the rod up to the holder, since in this case the electrode holder itself will deteriorate. In addition, when making a weld with a short electrode length, the weld pool is blocked by the holder, and it becomes impossible to visually control the progress of the seam.

Welding thin metal

When welding thin metal, that is, 0.5-1 mm thick, the depth of the weld pool is greater than the thickness of the metal. Therefore, if you simply weld such metal without preparing the edges, it will be burned through. To prevent this from happening, flanges are made when welding two parts end-to-end.

When the flanged edge melts from the heat of the arc, the bent parts melt inward, close the entire gap between the workpieces and, together with the metal that comes from the electrode, form a seam. Thus, the metal does not melt through, but a completely filled seam is obtained. (Experienced and highly qualified welders are able to weld such thin metal without flanges, but amateur welders, as a rule, do not succeed.)

Electrodes for welding cast iron

For decorative welding of surface defects, steel electrodes Sv-08 are used.

To weld defects of processed non-working surfaces when repairing non-critical cast iron products of small sizes with small volumes of deposition, which do not require mechanical processing after welding, TsCh-4 electrodes are used.

Also, when welding cast iron, UONI-13/45 electrodes are used. They weld using direct current of reverse polarity.

Copper electrodes, for example OZCH-2 and OZCH-6, are used for welding small-sized products with small defects, operating under minor static loads and requiring tight seams made of gray or ductile cast iron. These electrodes provide a fairly strong welded joint that can be easily processed. Welding cast iron without heating can also be performed using filler materials in the form of nickel-based cast iron alloys with a nickel content of more than 20%. The resulting weld is characterized by high ductility and low hardness.

For welding products made of high-strength, gray cast iron, as well as for making dissimilar joints of cast iron with steel, electrodes of the TsCh-4A grade are used. Hot welding is carried out as follows: mechanical processing of the workpiece; molding of welded parts; heat; welding and cooling of welded parts. The parts can be heated using a gas burner.

Electrodes for this type of welding are made from rods that are homogeneous to the base metal. For example, ECh-1, ECh-2, PCh-1, PChS-1, PChS-2 are used. The heating temperature, depending on the type of cast iron and the volume of the part being welded, is 300-700°C, followed by cooling by 100%. Welding cast iron is performed using reverse polarity current. Recommended welding modes are presented in the table.

Welding must be carried out in small sections 30-60 mm long with layer-by-layer cooling in air to 60°C. Immediately after welding, the seam is hammered with light hammer blows.

obinstrumente.ru

Electrodes for welding, marking of electrodes, which electrodes to choose

One of the main conditions for obtaining a high-quality and correct welding seam is high-quality, correctly selected electrodes for welding with an inverter machine. Modern market has a very wide range of electric welding products. They all differ in type, coating material and other characteristics. Below we invite you to familiarize yourself with the available options and choose the most suitable one.

Types of electrodes for welding with an inverter machine

All existing electrodes for electric welding are divided into consumable and non-consumable. The consumable electrode is based on a wire rod made of metal wire, coated on the outside with a special coating. Thanks to the coating, the welding arc can burn stably, and the coating also provides good protection seam from gas and slag.

Electrodes, the purpose of which is to weld steel of unknown composition, as well as copper, stainless steel, cast iron and other metals, are made from a specific alloy. Non-consumable types of electrodes are most often used when working with argon welding.

Working welding elements are available in different lengths and diameters. The length of the electrode depends on the alloying characteristics of the steel wire rod of the product, and can range from 30 to 45 centimeters. Regardless of the diameter, all types of electrodes find the widest application. The only exception is the diameter of 1.6 mm. This type of electrodes is available upon request only. They are practically not used by Russian welders.

The most commonly used classification of all existing electrodes is according to their purpose. Based on this parameter, electrodes are divided into:

Designed to work with elements made of carbon and low-alloy steels. For working with high-strength heat-resistant steels. “Electrodes for stainless steel” - for working with high-alloy steel. "Electrodes for aluminum". Electrodes for welding copper parts and products based on it. Electrodes for cast iron. For repairs and surfacing. For welding work on metals whose composition is not determined.

Classification according to the type of electrode coating is also quite often used. There are four main types of coatings, but only two are widely used.

Basic type electrodes.

They got their name because the electrode rod has a so-called base coating. The most popular among the main electrodes is the UONI 13/55 model. The use of this product allows you to obtain high-quality seams with high impact resistance, strength and ductility. In addition, crystalline cracks rarely appear on such seams, and they are poorly prone to “aging.” UONI electrodes are typically used for high-responsibility welding work and products that will operate in harsh conditions. The disadvantages of this type of electrode include arc elongation, instability of the coating to moisture and rust, and the appearance of scale or oil in the weld area. Taken together, all this can lead to the appearance of micropores. In addition, the main electrodes can only operate on reverse direct current.

The second type of electrodes has a rutile coating.

These products are used when welding parts made of metal with a low carbon content. The most commonly used grade is MP-3. These electrodes have good technological qualities, namely:

The electric arc burns steadily on both direct and alternating current. The hot metal practically does not splash.

High quality seams in any position of the parts being welded.

Slag is separated very well. Electrodes can be used to work on dirty and rusty surfaces. The finished welds have a very good view, without pores and cavities.

Well suited for welding steel parts with low carbon content.

We select an electrode taking into account the material and operating mode

The correct choice of electrode for work, of course, plays a big role, however, in addition to this, you still need to know what polarity and current you need to work with in each specific case. Almost all inverters use direct current. When working with direct current, the electrode part can be connected in several ways, namely:

If the polarity is straight, the electrode is connected to “minus” and the part to “plus”.

When working with reverse polarity, on the contrary, the electrode is connected to “plus” and the workpiece to “minus”.

During operation with direct polarity, a higher temperature is generated when compared with the same values ​​when operating with reverse polarity. Therefore, working with reverse polarity makes sense in the following cases:

If you need to weld thin sheet metal. Since the temperature at reverse polarity is lower, the workpiece will not burn.

When working with high-alloy steel grades. “Return” in this case significantly reduces the likelihood of the part overheating.

It is better to work with direct polarity with massive workpieces that need to be well heated for high-quality welding.

In welding, there are three main characteristics on which the quality of work directly depends:

Welding current. Diameter of the workpiece.

Thickness of working material.

First, you need to decide on the relationship between the diameter of the working element and the thickness of the part to be worked with. For example, steel up to 1.5 mm thick. It is almost always cooked using a semi-automatic machine or argon welding.

Electric arc welding is practically not used for this. Steel 2mm thick is welded with electrodes with a diameter of 2.5mm. To qualitatively weld steel 3 mm thick, you will need electrodes with a diameter of 2.5-3 mm.

For steel 5 mm thick - electrode 3.2-4 mm. For working with products with a thickness of 6 to 12 mm. working elements with a diameter of 4-5 mm are used.

For steel thicker than 13 mm. use a 5 mm electrode.

An important point: the larger the electrode diameter, the lower the operating current density. As a result, the arc begins to oscillate, “wander,” change length and behave unstable. Because of this, the depth of the seam decreases, and the width, on the contrary, increases. In most cases, manufacturers of such electrodes indicate the required welding current indicators on the packaging. If the manufacturer has not provided the necessary information, you need to focus on the following indicators:

For an electrode with a diameter of 2 mm, a current of 55-65 A is required. For an electrode with a width of 2.5 mm - 65-80 A. For 3 mm - 70-130 A. For 4 mm – 130-160 A. For 5 mm – 180-210 A.

For 6 mm – 210-240 A.

Based on the above, when choosing a working element of a certain diameter for welding work, you must first of all pay attention to the thickness of the workpiece. If you work on thin metal with a large-diameter electrode, or exceed the welding current, then pores will certainly remain in the weld.

Marking of welding electrodes

The most common brand among foreign electrode manufacturers is ESAB.

The name of each type of electrode of this brand begins with OK, followed by a 4-digit designation. There are many variations on sale, but the most common are the following:

OK 46.00 - the electrode is almost similar to the properties of the MP-3 brand. Excellent for low alloy and carbon steels. Suitable for AC and DC. Provides high quality seam.

OK 48.00. Designed for work on critical structures. They operate on direct current only.

OK 61.30 and OK 63.20. They are used when welding stainless steel of almost all brands. Before purchasing, be sure to ask your sales consultant whether these electrodes are suitable for working with a specific grade of stainless steel.

OK 68.81. Great model. Excellent for welding steel products of indefinite composition and difficult-to-weld parts.

OK 92.60. Electrodes for cast iron and connecting cast iron parts with different types steels

OK 96.20. Electrodes for aluminum.

Criteria for selecting suitable electrodes

Having analyzed all of the above, we can identify several main points that you must pay attention to when choosing electrodes for electric welding. First, you need to determine exactly what metal you will be working with and select an electrode based on the type of metal. If you have to work with a critical design, it is better not to save money and buy products from a well-known manufacturer. For example, the Swedish products that we mentioned above have proven themselves very well. If you need to weld carbon steel parts, be sure to keep the surface clean. If it is coated with oil, damp or rusty, you should purchase electrodes that have a rutile coating. If you have to work on critical structures, it is recommended to use working elements with a basic coating.

However, in any situation, you need to remember that all products require preliminary surface preparation. In addition, it is necessary to accurately determine the thickness of the workpiece, based on which to select the optimal welding current. The selection process must be approached as responsibly as possible. If the electrodes are chosen correctly, then even on the cheapest inverter you can weld almost any metals on the most high level.

svouimirukami.ru

How to choose electrodes for welding with an inverter

In the welding craft, the ability to choose the right electrodes depending on the type of connections and grade of steel is a very important professional skill. In this article we will tell you about the main types of coating electrodes for MMA welding and explain how to use them for their intended purpose.

How they work and how they differ

An electrode is a simple metal rod that melts when lit. electric arc and fills the seam between two parts, simultaneously heating their edges. The electrode coating, when burned, ionizes the medium and maintains continuous arc burning. In addition, during combustion, the composition releases gases that displace oxygen from the weld pool and forms slag, which floats to the surface of the molten metal and covers it, protecting it from corrosion, cracking and other negative effects during cooling.

Understanding the essence of how electrodes work is very important to explain such a huge number of their varieties. They differ not only in the strength characteristics of the seam, but also in its position and the type of welding current used.

Difference between electrodes according to the location of the seam

Let us briefly recall how the orientation of the weld pool in space can change and how this affects the welding technique. The most convenient is the lower position of the horizontal seam, which can be flat or angular. In this case, the melt effectively fills the seam and chamfer, and a uniform crust of slag is formed on top, which is easily separated. Almost all brands of electrodes, with the exception of special ones, can be welded in the lower horizontal position.

Vertical seams are more difficult to weld. Typically, the welding technique is used with a lift-off welding process from the bottom up. Accordingly, the electrode coating should allow the arc to be ignited quickly and briefly and effectively direct the molten metal. Also, vertical seams can be welded without tearing, but for this the coating must be thicker than usual so that a semicircular hole is formed at the point of contact on the electrode.

The upper (ceiling) location of the horizontal seam is considered the most difficult in MMA welding. It is almost impossible to weld such seams without tearing them off; more often they are deposited using the spot method with an overlap of 3/4 of the previous deposit. Electrode coating for ceiling seams promotes rapid melting of small portions of metal and their equally rapid cooling. Slag from electrodes also behaves differently. For the most part, it flies to the side (the electrode is held at an angle) and covers the previous sticking point. Electrodes for ceiling welding are most sensitive to current mode and polarity.

Type and polarity of welding current

As you know, inverters have alternating or direct current at their output, the latter has direct and reverse polarity connections. Most electrode welding problems are solved by reverse polarity, in which the electrode is connected to the positive “+” contact, and the workpiece is connected to the negative “-”. The peculiarity of reverse polarity is that electrons, continuously moving from the negative pole to the positive, heat the electrode and its coating, and the metal of the part is heated only by indirect radiation.

With direct polarity, the flow of electrodes is directed from the electrode to the part and heats it directly. The electrode burns more slowly by adding small portions of molten metal to the bath. It is useless to expect that such welding will effectively fill a joint with a wide gap; straight polarity is used to join well-fitted parts with uniform weld thickness. For example, this method is good for welding sheets of metal, the seam is minimally noticeable. Thanks to more high temperature weld pool with direct polarity, it is optimal to weld massive parts that require maximum heating depth.

AC welding typically produces a lot of spatter of molten metal. The coating of electrodes for AC welding has additives to stabilize the arc and special alloying impurities that make the melt more viscous. The quality of the weld when working with alternating current electrodes is considered the highest for RDS.

Explanation of symbols

There are two main specifications according to which electrodes are marked: the domestic GOST 9466 and the European standard ISO 2560. Each of them uses own system symbols.

Top line - Т11-XXX-Y-ZN:

· T - type of electrodes, “E” for MMA welding;

· 11 - metal yield strength in MPa;

XXX - brand of electrodes;

· Y - electrode diameter;

· Z - purpose of the electrode (U - low-alloy and carbon up to 60 kgf/mm, L - alloyed over 60 kgf/mm);

· N - coating thickness.

Bottom line - E-AAA-B-C-D:

· E-AAA - type and standard index that determine the strength characteristics of the seam;

· B - type of coating;

· C - seam position;

· D - current characteristics.

· T - designation of the type of electrodes, “E” - for MMA welding;

· ХХ – metal yield strength in MPa;

· Y - impact resistance index in MPa;

· SS - type of electrode coating;

Types of coatings

The acid coating (A) strongly melts the weld pool, making the metal susceptible to cracking as it solidifies. Currently replaced by rutile acid.

The main (B, B) coating ensures greater viscosity of the metal in the bath and uniform heating of the part. Such electrodes are intended for welding loaded structures, but they should be calcined before use to avoid the formation of pores in the metal.

The cellulose (C, C) coating burns in an arc almost completely, almost without forming slag. This type of electrode is one of the few that can be used to weld vertical seams from top to bottom.

The basis of rutile (P, R) coating is titanium dioxide. The electrodes are optimal for pull-off welding: they ignite and hold the arc well and deposit metal evenly. Rutile coating provides complete control over the welding process and allows you to vary the arc length over a wide range.

Rutile-cellulose (RC) coatings inherit the positive qualities of both types. It is these electrodes that are used for installation in cramped conditions; they leave an aesthetic facial seam that does not require further processing.

Most popular brands

The lower the complexity of the seam, the more convenient the electrodes are to use; some literally weld themselves. These, first of all, should include the famous E46 brand MONOLITH, also known as ANO-36, popularly called “school” electrodes. It’s really easy to cook with them: the rutile-cellulose coating holds the arc well even at very low currents, the metal is transferred in small and medium drops, filling the bath well. However, such electrodes should not be used for critical structures: due to the increased silicon content, the weld loses its ductility and impact strength.

It is recommended to weld assemblies and connections operated outdoors, including metal frame structures with suspended cladding, using electrodes whose coating contains alloying additives. Such seams have a much higher yield strength, and they are subject to corrosion to a much lesser extent due to the low hydrogen index. An example of such a brand is OK-48. They have a base coating and melt the metal to a viscous-liquid state, setting the optimal degree of heating, and are suitable for welding in any position. If a penetration of 12 mm or higher is required, it is recommended to pre-weld the seam with organic-coated electrodes such as ANO-7 and ANO-8.

For welding structures with oscillating types of loads and pressure vessels, OK 61.35 electrodes are used. They have a basic coating, the metal is very viscous when melted, and the seam is practically insensitive to intercrystalline corrosion.

http://www.rmnt.ru/ - website RMNT.ru

digest.wizardsoft.ru

The welding inverter is easy to use and has an affordable price. Even a home master can master the principle of its operation without having high qualifications.

The inverter is superior in many respects to large-sized standard transformer units and welds all types of metal parts and structures. The complexity of the work performed, the service life of the inverter, the reliability and quality of welding seams depend on the electrodes used.

The choice of electrodes is complicated by the wide range. There are over two hundred different brands, differing in diameter, type, and coating material. A clear understanding of the operating principles of the unit (inverter) allows you to determine the best electrodes for performing welding work with an inverter.

Welding with an inverter machine

A characteristic feature of any type of inverter is constant performance and stability of the welding current, guaranteeing the quality of the resulting seam and the formation of alternating voltage that forms the welding arc. The connection of the surfaces to be welded is carried out by the melting method.

The qualitative indicators of the reliability of the unit are due to its design feature. Each device, regardless of type, consists of the following elements:

• frequency converter;
• control systems (center);
• transformer;
• power rectifier;
• network filter.

They all form general scheme inverter, and the main tool for welding is the electrode.

They are electrically conductive metal rods (cores) with a special protective coating - coating. The arc temperature during welding causes the core to melt. This process is accompanied by burning and melting of the coating. The combustible coating turns into a gas cloud, blocking the access of oxygen. The melting part of the coating becomes liquid, covers the molten metal with a thin layer, and protects it from interaction with oxygen.

Presence of chips on protective coating unacceptable. Violation of the coating does not allow achieving uniform heating and high-quality execution of the seam. In order for the arc to be in the center, you need to choose electrodes whose tips have a coating thickness that is uniform on all sides. The coating must be dry. Electrodes with wet coating do not ignite easily. You can dry them, but this will reduce their performance characteristics.

Protective covering

Electrodes differ in the type of coating used. There are four types of coatings:

• main or SSSI;
• cellulose;
• rutile;
• sour.

Rods with cellulose and base coating create elastic, reliable, impact-resistant seams when carrying out welding work with direct current. Rutile with acid coating are universal. Coatings are used for welding with both direct and alternating current.

Electrodes coated with acidic coating are toxic. Work with them is carried out in closed spaces only when the rooms are equipped with good forced exhaust. Rods coated with rutile, which has a bluish or greenish tint, are easy to ignite. This parameter remains unchanged when operating the inverter at low open circuit voltage.

Core

Consumable type metal rods used when working with an inverter are selected in accordance with the type of metal of the parts and structures being welded. The welding wire from which the electrode core is made must comply with state standards.

There are three types of electrodes for inverter devices: alloyed, highly alloyed and carbon. Each of them is made from a corresponding type of welding wire. When working with high-alloy and stainless steel experts recommend using rods TsL-11, carbon steel - ANO-21, UONI-13/45, MR-3S, cast iron - OZCH-2, low-carbon steel - ANO-4 and ANO-6.

What types of electrodes are there?

Conventionally, rods for working with an inverter-type welding machine are divided into two categories. The former are intended for complex and critical work, and the latter can be used when welding on less demanding and simple areas. The first group consists of UONI melting-type electrodes, and the second group consists of ANO, MP-3.

ANO brand electrodes are chosen for performing simple welding for domestic needs. They are suitable for working with almost all types of inverter welding machines. They are most widespread among home and novice craftsmen. Electrodes of the MP-3 brand are considered unpretentious and universal. They can weld wet, rusty, poorly cleaned metal surfaces.

The SSSI brand is more “capricious”, it requires certain skills, but it allows you to weld together surfaces of any complexity and obtain the most dense seams. Electrodes in this category are often chosen by professionals. A novice welder with no actual experience will find it difficult to work with them.

Which electrodes are considered the best?

Experts identify the following brands of electrodes intended for welding with inverter machines:

• 1. UONI-13/55

Ensures consistently high seam quality with optimal indicator density. They can be used in conditions of both high and low temperatures. This does not affect the result of the work.

• 2. ANO (in particular ANO-21)

They do not require preliminary calcination or effort for ignition, and show consistently high welding results, performed both by an experienced craftsman and by a person using a welding machine for the first time.

• 3. MR-3

Universal melting-type rods for working with metal structures in almost any condition: wet, covered with rust and dirt.

• 4. MR-3S

Used for welding critical areas where the requirements for seams are the highest. The connection of structures and parts with this type of electrodes is carried out using both direct and alternating current.

• 5. OK 63.34

Designed for welding stainless steel and structural steel. They form seams with a fine wave and a smooth transition to the main surface of the connected structures, elements and parts.

Characteristics and Application

UONI-13/55

Rods with a basic coating are recommended when working with low-alloy and carbon steel, designed for DC welding machines and inverters. The advantage of electrodes of this brand is the production of plastic seams that can easily withstand shock loads and low temperatures.

These electrodes also have disadvantages. The required minimum voltage to ignite the rod at idle speed should be 65-70 V. If there is rust, oil and other contaminants on the edges of the structures and parts being welded, the seams will be porous and of poor quality.

ANO-21

Electrodes coated with rutile coating are used for welding carbon steel of small thickness. They are easy to light both during the first and repeated use. They form a fine-scaled seam of small waves. Work with alternating and direct current of any polarity. Need to warm up before use. The rods are calcined for about 40 minutes at a temperature of 120 degrees. Their use is permissible for welding water and gas supply pipes.

MR-3

They ignite when working even with devices that do not have a very high current-voltage characteristic (volt-ampere characteristic). Provide good protection and allow you to control the position of the weld pool. There may be some difficulty starting the fire. If this happens, the electrode is calcined at a temperature of 150-180 degrees for 40 minutes. Used for all types of seams, with the exception of vertical top-to-bottom seams.
Lights up quickly and easily. For this quality they are also called “sparklers”. Professional welders do not use them in cases where small movements are necessary for good warm-up. Soft welding and complete absence the need to clean the surfaces to be joined made them an ideal choice for beginners learning the basics of welding.
OK 63.34

Used for welding vertical seams, making overlap and butt joints, and multi-pass welding. The minimum open circuit voltage for working with rods of this brand should be 60 V. The formation of slag during welding is minimal and can be easily removed.
Requirements for electrodes for inverter welding

The best ones for working with inverter welding machines are melting-type metal rods, which have the following characteristics:

• 1. Provide ease of welding work

If the electrode is selected incorrectly, that is, does not match the composition of the metal, the welding process becomes significantly more difficult.

• 2. Shows a high-quality seam result

An important factor when performing sealed and outdoor work. High-quality electrodes should allow you to obtain both concave and flat seams.

• 3. Form detachable slag

The quality of the electrode used can be easily checked by slag. Bad seams fly off along with the slag being beaten off. If this happens, the reason lies precisely in the electrodes, and not in the skills of the welder.

• 4. Meet sanitary standards

The electrodes used must be made in full compliance with existing government regulations and standards.

• 5. Allows welding on corrosive metals

The permissibility of such work is an exception and not a universal practice. If such a need arises, the UONI, ANO and MP-3 brands will ensure quality of work in this case as well.

Electrode diameter

With increasing wall thickness metal surface the required time for welding work increases. The thicker the surface, the larger the diameter of the electrodes used. Rods with a thin diameter burn out very quickly and are most often used on tacks. Working with them requires a certain skill in welding.

“Troika” (rods with a diameter of 3 mm) is suitable for welding structures and elements with a thickness of 3-4 mm, “four” - for elements with a thickness of 4 to 9 mm, “five” - for elements with a thickness of 9-10 mm. For areas where major sealing is not required, rods with a diameter of 0.5-2 mm can be used. Profile structures for maintenance and assembly it is permissible to weld using electrodes up to 2 mm.

You need to purchase rods only in specialized stores that guarantee the quality of the products offered. This is due not only to the characteristics of the proposed electrodes, but also to compliance with the rules of their transportation and storage, the presence of all necessary documents and certificates. Damp elements can be dried, damaged ones cannot be used.

All necessary information information about electrodes is indicated on the packaging. It is recommended to choose welding rods with the lowest slag rate. Electrode consumption is no less important. The parameter indicator is also written in the labeling. Please note that the value may change upward. It depends on the purpose and quality of the surfaces being welded.

Welding rods are purchased according to their purpose. If the electrodes used are intended for another type of welding, the result of the work done will be of poor quality, and its safety indicators will sharply decrease. It is also necessary to take into account the area of ​​application of the welding machine.

If the inverter is used for domestic needs, electrodes for them are selected with a diameter of 2 to 4 mm. To "grab" metal constructions, electrodes of the MR and ANO brands are suitable. The quality will not cause any complaints. To weld utility forks, for example, water supply or heating pipes, it is necessary to use SSNI rods that ensure the reliability of the resulting seam.

For a novice welder, choosing an electrode can be a problem: there are more than two hundred brands with different properties, purpose and characteristics. Moreover, about 100 brands are suitable for manual arc welding with inverter machines. It’s impossible to talk about everyone, and to begin with, it’s not necessary. Let’s just briefly describe the main types and which electrodes for inverter welding are most suitable for beginners. We will also talk about what diameter to take and what current to set for welding metal of different thicknesses.

What is an electrode and what is the coating for?

An electrode is a piece of metal wire with a special coating - coating. During welding, the core melts due to the temperature of the arc. At the same time, the coating burns and melts, creating a protective gas cloud around the welding area - the weld pool. It blocks access to oxygen contained in the air. As the coating burns, part of it turns into a liquid state and covers the molten metal with a thin layer, also protecting it from interaction with oxygen. So the coating provides good quality seam

Before starting welding, any electrode is inspected: the coating should not be chipped. Otherwise, you will not achieve uniform heating and a high-quality seam. Also pay attention to the tip of the electrode: the thickness of the coating should be the same on all sides. Then the arc will come out in the center. Otherwise it will be displaced. For experienced welders this is not a big deal, but for beginners it can create significant problems.

It is necessary to monitor the moisture content of the coating. Some of them at high humidity light up very poorly (for example, SSSI). Due to such “capriciousness” of the coating, they need to be stored in a dry place, ensuring as airtight packaging as possible. You can put the box in a bag, and also put in a few bags of salt, which are found in shoe boxes.

You should not buy wet electrodes: they can, of course, be dried, but their characteristics will decrease. If it does happen that the electrodes become damp, they can be dried in the usual household oven at low temperatures (they are usually indicated on the packaging). The second way is to put it in a dry, well-ventilated area for a long time.

Types of coating and their characteristics

There are only four types of coatings:

• Basics.
• Rutile.
• Sour.
• Pulp.

Basic (USSI) and cellulose coatings are only suitable for DC welding. They can be used on critical seams: they create a strong, elastic seam that is resistant to impact loads.

The other two (rutile and acidic) can work with both alternating and direct current when welding. But acidic coating is very toxic: you can only work indoors if workplace equipped with forced exhaust.

Rutile coating has a greenish or blue tint, the electrodes are easy to ignite. They ignite well even if the inverter has a low open circuit voltage (for reliable ignition of the main coating, a good current-voltage characteristic is required). When welding with rutile electrodes (MP-3), the metal hardly splashes, but there is a lot of slag and it is not easy to remove: you have to work with a hammer.

How to choose electrodes for inverter welding

First of all, the composition of the core is selected: it must be similar to the type of metal being welded. Structural steel is the most commonly used material in households. The electrodes should be made from the same wire. Sometimes you still have to cook stainless steel. Then the core should also be made of stainless steel, and for highly alloyed and heat-resistant ones it is made of metal with the same characteristics.

You can perform all the work around the house or at a construction site using just a few brands of electrodes:

• SSSI 13/55
• ANO 21
• OK 63.34

They are recognized by many as the best electrodes for beginners who work with: they are easier to work with, at the same time, they allow you to weld high-quality seams even in the absence of significant experience. Below are the characteristics and general application of those consumables that many experts consider good electrodes for an inverter. In any case, they are often recommended for beginning welders to gain experience.

Electrodes with rutile coating MP 3

These are perhaps the most popular welding electrodes for inverters among beginners: UONI 13/55 (To enlarge the picture size, right-click on it)

Most often, beginners are advised to start mastering welds with MP-3 electrodes. They light up easily, even with a not very good current-voltage characteristic of the welding machine, provide good protection for the weld pool, and make it quite easy to control its position. If the electrode does not ignite, calcine it at a temperature of 150-180° for 40 minutes.

They are used in devices with alternating current (welding transformers) and direct current ( welding rectifiers and inverters). Inverters are usually connected with reverse polarity (+ on the electrode). Suitable for any type of seam, except vertical from top to bottom.

MP 3 electrodes are not picky about the quality of the surfaces being welded. They can be used even on untreated, rusty and wet parts. Welding is carried out with a medium (2-3 mm) or short arc.

The MP 3 feature is very important for novice welders: they “hold” the arc well and are easy to work with. This is why not all professionals love this brand: they call them sparklers. They cook too softly: slow movements are necessary for good heating. What the pros don't like, is just what beginners need. Try to start learning welding with MP3. Everything should work out for you.

Electrode diameter LEZ MR-3, mm	Length, mm		Pack weight, kg	Price, rub
2,0	250	40-60 A	1,0	146
2,5	300	60-100 A	1,0	120
3	350	70-100 A	1,0	95
4	450	80-170 A	1,0	91
5	450	130-210 A	1,0	91

UONI 13/55 with basic coating

Electrodes preferred by professionals for the UONI 13/55 inverter (To increase the size of the picture, right-click on it)

These are perhaps the most widespread and popular electrodes with a basic coating. They are recommended for welding carbon and low-alloy steels. Suitable for connections of critical structures. The seams are resistant to shock loads and ductile, and withstand low temperatures well.

The disadvantage of these electrodes is that they ignite well only when the idle value of the inverter is sufficiently high (above 70 V). Second significant drawback: high requirements for cleaning and processing of welded metals. If rust, dust, oil or other contaminants remain on the edge, it will become porous.

You can work with UONI 13/55 only on DC welding machines, including those with inverters, with reverse polarity (+ applied to the electrode), and with a short arc (keep the tip of the electrode closer to the surface to be welded). Minimum open circuit voltage 65 V.

Electrode diameter UONI 13/55 (manufacturer: Mezhgosmetiz)	Electrode length, mm	Recommended welding current, A	Retail price of a pack, rub
2,0	250	30-60 A
2,5	300	40-70 A	127 RUR
3	350	80-100 A	116 RUR
4	450	130-160 A	111 rub.
5	450	180-210 A	110 rub.

ANO 21

This type of rutile-coated electrode is designed to work with thin carbon steels. () When using them, the arc is ignited easily (including when re-igniting), the seam turns out to be finely scaly (from waves small size), the slag is easily separated. ANO 21 electrodes can be used for welding water or gas pipes.

They work with both alternating and direct current of any polarity. Before welding it is necessary heat treatment: they are calcined at a temperature of 120°C for 40 minutes.

Stainless steel electrodes OK 63.34

If you need to weld stainless steel, try OK 63.34. They can also cook structural steel. This produces a seam with a small wave with a smooth transition to the main surface of the metal. The amount of slag is small and can be easily removed.

This electrode is good for welding 6-8 mm of metal, passing from top to bottom. Suitable for multi-pass welding of butt and overlap joints. Works with direct and alternating current of any polarity, minimum open circuit voltage is 60 V.

For welding you will also need a mask. To make your work easier, take

How to choose the diameter of the electrode, how to connect it and what current strength to set

Choosing the brand of electrodes for the inverter is not all. Even if you have made your decision, at least three questions remain:

• what electrode diameter to use when welding;
• what current to set;
• Which output “+” or “-” should the electrode be connected to?

First things first. Let's start with what diameter of the electrode is needed for welding. In general, it is recommended to proceed from the thickness of the metals being welded: for small thicknesses, an electrode is taken with a diameter of the same size as the metal. If you are welding metal 3 mm thick, then use electrodes of a similar size. If you are cooking something thicker, take 4 mm accordingly. But large electrodes will be difficult for beginners to work with. Start mastering welding with a metal thickness of 3-4 mm. To do this, use 3 mm electrodes, or as they say “three”.

Regarding how to connect the electrodes to which output. IN technical specifications The package most likely indicates what polarity the electrode is intended for. When connecting in reverse, an electrode is connected to the positive output, and a clamp is connected to the negative output, which is attached to the part. With direct polarity, a plus is placed on the part, and a minus is applied to the electrode. How it looks on a welding inverter is shown in the photo.

How are these two connection types different? The flow of electrons has different directions. As you know, electrons move from minus to plus. Therefore, when welding, it turns out that the element that is connected to “+” heats up more. By changing connection modes you can control the intensity of metal heating.

Let's consider several situations. For example, you have a 3 mm electrode, 2 mm metal. If you apply “+” to a part, burnout may result. Therefore, in this case it is better to use reverse polarity, at which the electrode will heat up more. If you want to weld 6 mm metal with the same three, it is better to do it with direct polarity: this way the heating of the metal will be deeper and the weld will be stronger.

Welding current

In general, when installing an electrode, the welding current strength for the inverter is set depending on the diameter of the electrode used. In general, there are recommendations on each pack, but you can do without them: take 20-30 Amperes of current for each millimeter of diameter. It turns out to be a fairly wide range, but then you also need to consider how you will lay the seam: with or without tearing. For welding without separation, lower currents are used, for welding with separation, higher currents are used.

For example, for an electrode with a diameter of 3 mm, the calculated current is from 60 A to 90 A. They actually work in the range from 30 Amperes to 140 Amperes. When welding without separation, the current is set to about 70-90 A, with separation - 90-120 A. These parameters can “walk” in both directions: it also depends on the speed of movement of the tip of the electrode, on the grade and “fluidity” of the steel being welded, on the position of the seam (for vertical and horizontal seams they put a little less, for the ceiling - even less).

In general, even the currents recommended by the manufacturer are far from a requirement. Start with them, and then select them so that it is convenient for you to work and the seam turns out well. You should get a high-quality connection, and you will select the ratio of current strength and speed of movement experimentally. In this case, focus on the condition of the weld pool. It is your main indicator of quality.

Now you know not only how to choose electrodes for inverter welding, but also how to connect them, what diameter you need them for this work, and how to select the current for each type of electrode and weld. Now let's talk a little about electrode holders.

Electrode holders

One of the welding cables has a holder into which the welding electrode is inserted. They are of two types:

• with a trigger key, the electrode is clamped in them automatically when the spring-loaded key is released, and released when you press it;
• threaded - the handle twists and unwinds, releasing or clamping the inserted electrode core.

Which one is better? It's up to you to decide, but if you accidentally press a key, you may drop the electrode while welding. Nothing bad happens, but it’s unpleasant...

When choosing an electrode holder, the main thing is to pay attention to the current strength for which it is designed. Choose according to the maximum parameter that is available for your welding machine.

How to connect the cable to the holder welding electrode with a threaded clamp is shown in the video.

The disadvantage of the clothespin holder is that over time, the spring that presses the electrode core weakens, and the contact deteriorates. I have to install a new one. Watch the video to see how to do this on a clothespin holder.

Connecting the welding electrode holder is easy. There is just one caveat: with frequent use, the welding cable gets chafed by its edge. You can, of course, shorten the cable and re-terminate it, but you don’t always want to cut off even 10-20 cm. To prevent this from happening, find a hose whose inner diameter is the same as or slightly smaller than the outer diameter of the welded cable. Cut a small piece of it - 15 centimeters - and cut it lengthwise. Now you can put it on the cable, pull it up and secure it there.