How to properly make a weld with an inverter. How to weld correctly with a welding inverter. Forward and reverse polarity

One of the most simple methods metal connections - welding with an inverter. For novice welders, it provides an opportunity to quickly master simple skills and learn how to work with metal. When carrying out welding work, not much equipment is required, and it is affordable. Actions with hot metal require compliance with safety regulations. Therefore, you need to start by studying the equipment, protective equipment and methods of correctly performing operations.

Necessary equipment and equipment

First of all, you need to select equipment, protective equipment and learn how to use the inverter correctly. Required equipment:

Canvas leggings;
Robe or thick cotton clothing;
Welding mask with light filters;
Respirator;
Shoes with rubber soles.

Basics protective agent- This is a welding mask. It protects from splashes of hot metal, from bright lights and from strong ultraviolet radiation.

Equipment you will need:

welding inverter;
hammer;
brush;
electrodes.

The main characteristic of the inverter is the range of adjustment of the welding current. An inverter with a maximum current of up to 160 A can be used for both welding and metal cutting, but will experience significant overloads.

Another characteristic is the constant switching factor. This is the ratio of the operating time to the cooling time of the inverter. As the current decreases, the continuous switching factor increases and the device overheats less.

Taking both characteristics into account best choice for a novice welder there will be a machine with a maximum current of 180-200 A.

Welding Basics

According to safety rules, before starting, you should remove all flammable, wooden, paper, and plastic objects from the work area. The mask must be put on before starting the arc.

Electrode - metal rod, which is coated with a special flux coating. During welding, the consumable electrode fills the weld with metal. The coating also melts and covers the surface of the molten metal (weld pool), protecting the liquid metal from oxidation. The current strength determines the depth of metal penetration. The higher the current, the greater the distance over which the melt spreads during welding. The current strength is directly proportional to the diameter of the electrode. It is indicated in tabular form on the packaging with electrodes.

Types of seams

The bottom seam is the easiest to make. The parts lie horizontally, the weld pool is stable. With a horizontal seam it is much more difficult to keep the metal in the bath.

The vertical seam is made from the bottom up to prevent metal from flowing out of the weld pool. Otherwise, the quality of the seam will be poor. It will turn out uneven, with sagging and undercooked.

The most difficult weld is the ceiling one, because the seam and weld pool are located above the electrode. To perform ceiling seams, a highly qualified welder is required. Pipe welding is very difficult. There the bottom seam gradually turns into a vertical seam and into a ceiling seam. You need to be good at all of these types.

Operating procedure

To learn to cook welding inverter, you need to start from the bottom seam. A metal object is selected, for example, a thick corner or channel, such that a long seam can be made. For training, it is better to use MP-3 type electrodes. They easily ignite the welding arc and form a weld, which is important in the learning process for a beginner. To learn how to cook properly inverter welding, you can choose electrodes with a diameter of 3 mm. They are common and inexpensive.

Before you begin, you need to check and assemble the equipment. This requires:

Now you need to start welding. First, the arc is ignited. This requires:

Remove the coating from the end of the electrode by tapping it on the metal.
Ignite by striking. It's like striking a match. It is necessary to quickly move the electrode over the surface of the metal, not allowing it to stick. The question may arise why the electrode sticks when welding with an inverter, even with the anti-stick function. This occurs due to incorrect settings of the device or when using raw electrodes. The electrode can also stick due to uncleaned metal.
The electrode heats up and will be able to ignite an arc as it approaches the part. A section of molten metal is formed under the flared arc.

You can strike an arc by tapping it on a metal surface. The electrode must be kept at a constant distance from the part. Recommended distance 3 mm. You need to adjust the behavior of the bath by tilting the electrode:

Welding at right angles is carried out in hard to reach places. The bathtub is symmetrical, but it is inconvenient to work with.
Forward welding creates a deeper pool at the beginning of the weld.
Backward angle welding is used only in the bottom seam and in temporary tack welds.

The main weld defects arise due to uneven movement of the electrode, poor-quality coating or too fast movement of the tool.

Forward and reverse polarity

Direct and reverse polarity refers to the order of connection to the poles direct current. When connecting the electrode to the minus, and the metal workpiece to the plus, they speak of direct polarity. The melting zone is deep and narrow. With reverse polarity, a metal part is connected to the negative. When choosing polarity, you need to know which element should heat up more. It should be connected to the positive.

Straight polarity is applicable when cutting metal structures, thick-walled workpieces and in cases where it is necessary to create high temperature process. With reverse polarity, increased heating occurs at the electrode, and the metal is heated less. It is used for electric welding of thin sheets of metal to obtain a perfect seam or when it is necessary to prevent damage to the workpiece during operation.

For production repair work at home, in the garage, in the country, it is very important to learn how to weld metal. Tips for beginners can be found on numerous websites dedicated to welding. There are video tutorials and tutorials with a detailed story, how to properly weld metal with an inverter, and showing all stages of the work process.

Electric welder

Welding is used in almost all industries. It is difficult to name any segment of production that does not require the work of a welder. As a profession for beginners, it provides the opportunity to obtain promising work. Welders work on construction sites, creating systems of various communications and structures, in industry, applying their skills and experience, in shipbuilding, mechanical engineering, energy, agriculture, oil refining industry.

First of all, the welder must be fluent in welding equipment. At the same time, he, as a specialist, is required to have a thorough knowledge of the principles of its operation, preparing equipment for operation and identifying possible malfunctions. The welder must master the technology of carrying out welding work from preparing the surfaces to be joined to cleaning the weld and detecting it.

Specialist performing welding work, must know how to properly weld with electric welding, determine the optimal mode for welding various materials, set the current value. The complexity of the work of a gas-electric welder also lies in the fact that during the welding process, changing the welding mode can negatively affect their quality, therefore it is extremely important to correctly determine the welding speed from the very beginning. Qualified welders perform manual arc welding and can create quite complex metal structures and pipelines. The welder must know how to handle different types metals: alloys, steels (including those with limited weldability).

How to learn to cook with electric welding

Welding professions are taught in colleges, vocational schools, and courses. Training is carried out for three years on the basis of ninth grades and two years on the basis of eleventh grades.

If you are not going to work as a welder, but want to learn how to learn how to work with electric welding so that, if necessary, you can weld something yourself, you can use the advice in this article, or the literature from the “Electric welding tutorial” series. Of course, in this case you will not become a top-class welder, but this is not required. The main thing is to understand how to use electric welding correctly, learn the basics of electric welding, and learn basic work techniques.

Basics of electric welding

First of all, you need to purchase a welding machine and electrodes, which you need to stock up on in decent quantities, since during the learning process, you will have to ruin a lot of them before you achieve the first positive result. Choose electrodes for welding with your own hands with a diameter of 3 mm. They are the most suitable for teaching at home, since the thinner ones are suitable for very thin metal, which can only be welded by experienced welders, and thicker ones place a heavy load on the electrical network.

DIY electric welding

Video tutorials on electric welding

You can find a lot of instructions, manuals on the Internet, and video lessons on electric welding on the basics of performing this work are also available online. Below is a review of the course “5 lessons on electric welding”:

After watching an electric welding video, you can learn metal welding and take your first confident step in this complex and interesting craft.

In everyday life, the need to weld objects periodically arises. Very often such a need arises in the private sector. At large quantities work, you can turn to experienced welders, and when small jobs It is better to use an inverter welding machine.

This is the simplest, most affordable and convenient type of welding. It is available for everyone to work with. To do this, you need to know the principles of the welding process.

Welding with an inverter has become a breakthrough in the field welding machines, because outdated transformers are quite heavy and difficult to use. The advantage is that with inverter welding, spatter occurs less than when welding from a transformer.

An inverter is a welding machine that allows you to connect sheets of metal using an electric discharge. He has distinctive feature: has light weight and maximum capabilities, thanks to which he has access to work previously carried out by heavy and complex devices. The weight of the device depends on its power (from 3 to 7 kg).

You can transport it using a handle or strap. Cooling is carried out by ventilation holes in the case. This device consumes electricity, which flows only for arc work, and she carries out the welding process itself.

The device is insensitive to voltage changes. If there are constant fluctuations, you should pay attention to the required voltage, which is indicated in the inverter's passport.

Displayed on the surface of the device control knobs and indicators:

turns on and off with a toggle switch;
The voltage and current values are set using knobs on the front panel;
the panel has indicators informing about power supply and device overheating;
The outputs (“+” and “-”) are located on the front panel.

Additionally included in the set 2 cables available. One of them ends with a holder for the electrode, and the second has a clip in the form of a clothespin for securing the product. The device is connected via a connector located on the rear panel of the device.

Principle of operation

Inverter - electronic device, powered by electricity. When old welding machines are turned on, a strong and huge surge of electricity occurs, which may result in a power outage.

The inverter has storage capacitors, accumulating electricity and ensuring uninterrupted operation of the network. They gently ignite the arc of the inverter.

It is worth paying attention to the fact that electricity consumption depends on the diameter of the electrodes. The larger it is, the greater the consumption. In this regard, so as not to burn Appliances, before working with the inverter, it is necessary to calculate the maximum possible amount of electricity that will be consumed by the device.

It is worth considering that for each electrode diameter there is a minimum current, i.e., if you try to reduce the current, the seam will not work. If the current increases, it will work, but the electrode will quickly burn out.

The arc comes from the connection between the metal portion of the electrode and the metal being welded. Electrode and metal begin melt under the influence of arc temperature. The molten parts in its place form a bath. The electrode coating melts, part of which goes into a gaseous state and blocks the bath from oxygen. The other part of the coating (in a liquid state) protects the metal from air during welding and during the cooling process.

After welding and cooling of the metal, the liquid part is slag covering the seam with outside. After cooling, the slag is removed by tapping with a hammer.

The electrode melts during the welding process. So that the arc does not go out, you need to maintain its length, i.e. the distance between the metal and the electrode. This can be done by inserting the electrode into the welding site at the same speed and exactly along the seam joint.

With a short arc (about 1 mm), the metal is heated over a small area, and the weld comes out convex. At the point where the seam and metal meet, a defect such as an undercut (a parallel dimple near the seam) may appear. It reduces the strength of the seam.

A long arc is unstable, poorly protected from air, almost does not heat the metal, and the weld is not fully deep. Normal arc size - from 2 to 3 mm. A constant gap of this size will form a normal seam with good penetration.

To work with welding, the following protective elements are required:

Necessary prepare a safe place for welding:

Free space, absence of everything unnecessary.
Good lighting.
Work is performed standing wooden flooring, which protects against electric shock.

After this it is necessary adjust welding current(depending on the thickness of the metal and parts) and select an electrode (2−5 mm). Usually the strength of this current is indicated on the device body. Electrodes must be selected based on the brand of welding materials. Next, connect the ground terminal to the surface to be welded.

To obtain a reliable and high-quality connection before starting work metal should be prepared. Use a metal brush to remove rust from the edges, which need to be treated with a solvent (gasoline, white spirit). It is important to prevent the presence of grease and paint materials on the edges.

For beginners, it is better to perform a seam in the form of a roller on metal sheet with great thickness. The sheet must be placed horizontally on the table. There's chalk on it a straight line is drawn for guidance in the work along which the roller will be laid. To start welding, you need to ignite the arc. You can do this in 2 ways:

chirping;
tapping.

You can strike and hold the arc in both ways. Next comes the welding process itself, which produces a weld seam. Metal scale on top of the seam needs to be removed by tapping with a small hammer or hard object. The ability to control the length of the arc will provide excellent results.

The beauty of the seam is influenced by:

electrode inclination angle;
diagram of transverse and longitudinal movements;
speed of electrode movement.

How to weld a vertical seam

Welding such seams (slanted and ceiling) is quite difficult process. This is due to the fact that even molten metal is subject to the law universal gravity. He is constantly pulled down, which causes difficulties. Beginning welders will need to spend a lot of time learning how to do this.

There are 3 technologies for vertical seam welding:

Triangle. Used when connecting parts with a thickness of no more than 2 mm. Welding occurs from bottom to top. The liquid metal is on top of the solidifying one. It flows down, thereby covering the suture roller. The flowing slag does not interfere, since it moves along the solidified bath, which exits at a certain angle. Externally, the weld pool looks like a triangle. In this method, it is important to move the electrode accurately to completely fill the joint.
Herringbone. This type of welding is suitable for gaps between workpieces equal to 2-3 mm. Along the edge from the depth towards you, you need to use an electrode to melt the metal to the entire thickness of the workpiece and, without stopping, lower the electrode to the gap. After melting occurs, do all this along the other edge. You need to continue from the bottom to the top of the weld. This results in a uniform arrangement of molten metal in the gap space. It is important to prevent the formation of undercut edges and metal leaks.
Ladder. This method is used when large gap between the workpieces being joined and little dulling of the edges (or its absence at all). Welding is carried out in a zigzag manner from one edge to the other from bottom to top. The electrode stops at the edges for a long time, and the transition is made quickly. The roller will have a small cross section.

Welding polarity

Melting of the metal during the welding process is carried out under the influence of the heat of the arc. It forms between the metal and the electrode when they are connected to opposite terminals of the welding device.

There are 2 options for performing welding work: direct and reverse polarity.

In the first case, the electrode is connected to the minus, and the metal to the plus. There is a reduced introduction of heat into the metal. The melting point is narrow and deep.
In the second case, the electrode is connected to the positive, and the metal to the negative, resulting in a reduced heat input into the product. The melting point is wide, but not deep.

When choosing welding, it is necessary to take into account that the network element connected to the plus heats up more. Thick metal is welded with direct polarity, and thin metal with reverse polarity.

In addition to the fact that welding can connect parts, it you can cut them. To do this, you need to increase the current and cut off the part or corners. It’s just not possible to do it exactly.

By using this guide, you can gradually improve your skills and use inverter welding without any problems in the future. The main thing in this matter is practice.

Modern welding work involves the use various methods, it's not just traditional welding gas burner, but also ultrasound and electron beams. But for domestic conditions and simple work The preferred method is electric arc welding using an inverter. This method is simple, although it requires compliance certain rules and seam formation technologies. To learn this method yourself, you can use the basics of inverter welding for beginners.

Electric welding is the most commonly used method, providing a strong, durable connection of parts. The method works on the principle of plastic deformation, in which elementary particles of the electrode penetrate into the structure of the base materials of the parts being connected. As a result, new molecular bonds with the highest strength emerge.

For welding using an inverter, the following methods are used:

Gas press with the participation of acetylene-oxygen mixture. The method is different high performance performance, it can be used not only in everyday life, but also gas, oil industry, in the construction of highways, in mechanical engineering, civil engineering.
Contact welding is carried out using electric current low voltage, but with high strength. The method includes spot welding, end-to-end or with the formation of seams.
In some cases, the following types are used: thermite, friction, electroslag or roller.

How to choose the right equipment

Welding with an inverter for beginners begins with the right choice equipment. Currently offered on the market big choice welding equipment for household work or professional. When purchasing, too cheap devices are not recommended, as they can ensure the stability of the arc, which leads to poor welding of the seam and its low quality. In addition, for such devices there is a frequent “sag” of voltage, their weight is excessively large.

For electric welding, two types of equipment can be used: rectifiers and inverters. Rectifiers convert alternating current permanent, ensuring arc stability and good quality seam Inverters not only convert alternating current into direct current, but also provide exactly the voltage that is most suitable for welding. In addition, such devices are lightweight and compact, and their performance is quite high.

Inverters are the most effective for electric welding work due to their high performance, efficiency and compactness.

Externally, the inverter looks like a box weighing 3-7 kg with a carrying handle and cooling grilles on the body. The front panel has indicators for protection operation, networks, current regulation, cable connectors, and on/off toggle switches. The standard kit includes 2 cables with an electrode holder and a clamp for connecting the device.

Electrodes for welding work

The basics of work for novice welders include learning how to select electrodes that supply current to the point where parts are connected. For beginners, we recommend rods with a melting composition, hard and easy to work with, allowing even an inexperienced master to perform straight seam. For more experienced welders, it is better to use wire electrodes made from melting powder.

When choosing, great attention should be paid to the diameter of the electrode. Optimal size is considered 3 mm, for thin sheets you can take thinner rods, for massive and complex structures– with a large diameter.

Also, when choosing, you should be guided technical characteristics inverter, the type of surfaces being connected and the properties of the metal. For example, 3 mm rods are usually used, the welding current will be equal to 110-120 A. If the metal is thick, rods with a diameter of 4-5 mm are already required, and the current will be equal to 140-160 A.

Equipment to ensure work safety

Before starting welding work, you need to take care of protection. Welder equipment includes:

gaiters (special canvas mittens);
robe to protect the body from metal splashes and sparks;
mask (light filters for the mask are selected depending on working conditions);
respirator (required for working in confined spaces);
boots with rubber soles.

Grips are usually used when welding at heights, for ceiling works, in other cases you can take mittens from very thick fabric. For safety reasons, there should be a container of sand or water near the work site.

Instructions for a beginner

Electric and gas welding for beginners is the basics of work and use of equipment. Experienced professionals recommend attaching the cable with the electrode to the body, then pressing it with your elbow and carefully (the cable should retain some freedom) wrap it along the forearm to the hand. This will provide the most convenient conditions for welding, in which the hand will be free.

Attention: You cannot perform work with bare hands; it is mandatory to use a robe with long arms!

After preparation, the current is set on the inverter, according to the welding materials and the electrode, then you need to take a stable position, move your elbow slightly away from the body, lower the mask and start working. For beginners, it is recommended to start welding with parts larger than 20 cm, this allows you to practice working with long workpieces and breathing correctly. One of the most common mistakes for beginners is welding short parts in one go. As a result, on large areas it becomes difficult to work, and this negatively affects the quality of the seam.

The workpieces must be secured on the work table, then place the electrode at a right angle and move it towards the seam by about 30-45 degrees. The distance between the rod and the surface should be 2-3 mm; when welding with a backward angle, the slope is made towards the seam; with the forward angle method, the electrode is tilted away from the seam.

Attention: When welding, the electrode melts and decreases in size, so you must constantly monitor the distance and maintain the angle!

You can ignite the electrode using two methods:

by striking (the rod must be drawn along the surface);
by tapping (the electrode should be lightly struck on the surface in a perpendicular position).

If the rod is new, then it ignites immediately; for those that have already been used, you need to knock longer, since a slag film remains at the working end. Modern inverters make starting easier; for this you can use the Hot Start function. For beginners, the anti-stick function is great, that is, afterburner, which turns on when the rod approaches the surface too quickly. You can use another convenient feature against sticking - the Anti Stick function quickly turns off the current when sticking, which prevents the device from overheating.

Immediately after the arc appears, you should create a gap of 3-5 mm and keep it in one position. This will ensure excellent penetration and evenness of the seam throughout its entire length. It is better to start welding on a thread seam, gradually moving on to more complex options with oscillatory movements. These are methods such as herringbone, spiral, zigzag and many others. At the end of the weld, you need to make light oscillatory movements to the sides; the electrode is removed only towards the deposited metal, which will eliminate the crater.

Seam quality check

It is very simple to check the quality of the seam after finishing the work; you need to hit it with a hammer next to work surface. If everything is done correctly, the slag will completely fly off without leaving any traces - only a smooth, even seam with an optimal width will remain.

If the slag gets caught on something, this indicates lack of penetration, that is, the welding temperature is too low. An overheated seam will simply break upon impact.

The procedure for welding in a protected gas environment differs from electric welding in that the increased temperature in work area achieved by supplying gas. This method is optimal for joining parts made of copper, brass, lead, cast iron; after completion of the work, the metal can be hardened or cut. But this method has a big disadvantage - heating is carried out for a large area, that is, it is not suitable for precision work or small workpieces.

Conclusion

Welding requires utmost attention and strict adherence to work standards. Mastering the basics of welding is not very difficult, but it is necessary to competently approach the choice of equipment and electrodes, operating mode, and follow safety rules. After mastering the initial skills, you can move on to more complex work, but not before the hand gains confidence and clarity of movements.

Video lessons on welding with an inverter for beginners.

A welding inverter is a device that allows you to join metal by welding. Compared to a rectifier or transformer, welding with an inverter is easier, simpler and more affordable. How to learn to weld metal with an inverter?

Welding with an inverter: sequence of operations

Welding technology consists of a series of sequential actions. Their correct execution provides quality result- continuous strong connection two metal surfaces. How to properly weld metal with an inverter, what to pay attention to when learning to weld?

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Preparation for welding

Preparing the site for welding. The space within a meter radius is cleared of wooden, paper, and plastic objects. They can ignite from a hot electrode or spark. The inverter is installed on the ground (concrete floor) and connected to the electrical network. Two whiskers (wires with terminals “+” and “-”) are strengthened as follows: the plus terminal is attached to one of the metal surfaces to be welded, an electrode is inserted into the minus terminal (this connection is called direct polarity, it is the most common). The welder's body is covered with protective clothing (trousers, jacket, gloves), and a shield with dark glass (light filter) is put on the face.
We pick up the terminal with the electrode. We turn on the inverter (with the toggle switch) - a slight hum appears. We set the welding current value (with the regulator on the front panel). A traditional electrode with a diameter of 3 mm requires a welding current of 100 A. We lower the mask onto the face (Fig. 1).

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Ignition of the arc at the beginning of welding

Figure 1. Diameter versus thickness of parts.

Let's start welding. First you need to ignite the arc. With experience this will become easy. For a novice welder, igniting the arc is the first difficulty. Before ignition begins, the electrode is tapped on the metal surface to remove coating from its end. To ignite an arc on cold metal (at the beginning of welding), the striking method is used. It's like lighting a match. The electrode is passed over the metal, slightly touching the surface of the part being welded. For an inexperienced novice welder, the rod often sticks (glues to the metal). To unstick it, you need to sharply tilt the terminal with the electrode in the other direction (break off the rod from the part). If this does not work, turn off the power to the inverter. When the current supply is stopped, the sticking will disappear.
We strike until it forms electric arc. It is very bright, you can only look at it through a filter.
To maintain the arc, we fix the end of the electrode 3-5 mm from the metal. At the beginning of training, it will be difficult to maintain the required distance. If the electrode is too close, a short circuit will occur and it will stick to the part. If removed, the arc will be lost and will need to be re-ignited. During the welding process, the electrode is consumed, its coating burns out, and the base metal fills the seam between the surfaces being welded. Therefore, the hand with the terminal gradually moves down.

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Weld pool and weld seam

Figure 2. Diameter versus thickness of parts.

When the arc is ignited, a liquid pool of molten metal is formed. This is a welded bath. To connect metal parts over the entire contact surface, the electrode moves slowly along the interface. The weld pool (liquid metal zone) moves behind it. The end of the rod makes oscillatory movements (back and forth, left and right) relative to the seam between the two parts. This ensures the quality of the connection.
If the arc is lost (the electrode is too far from the weld), re-ignition is easier. To ignite an arc, it is enough to bring the end of the rod closer to a distance of several millimeters.
A bright electric arc and a less bright weld pool are clearly visible in the welding shield. The contacting welded surfaces in the welding zone are less visible. However, you cannot remove the shield and peek at the welding without a protective filter. IN best case scenario The eyelids will itch unpleasantly (a feeling of sand in the eyes). At worst, you can lose your vision without the possibility of restoring it.
When the rod is shortened to 5-6 cm, welding is stopped, the inverter is turned off and the electrode in the terminal is changed.
At the end of welding, the frozen metal seam is tapped with a hammer to remove the slag layer. A seam cleared of slag has a shiny surface.

This is the technology of inverter welding in general. Now let’s look in more detail at how to choose the right electrode and welding current.

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What electrodes should you use to weld metal?

An electrode is a metal rod coated on the outside with coating. The coating substance is a slag mixture, which also melts during welding, rises to the surface of the weld pool (it is lighter than metal) and protects the liquid metal from oxidation and saturation with nitrogen (Figure 2). In some cases, gas-forming additives are introduced into the coating composition, ensuring the release of gas when the electrode melts.

The composition of the internal rod is determined by the type of metals being welded (low-carbon and low-alloy steels, brass and bronze, magnesium alloys, titanium alloys). To weld ordinary carbon steel metal, UONII brand electrodes are used. They are also used for corrosion-resistant steels. UONII welding is performed only with direct current.

ANO marking rods are considered more universal. They are suitable for both forward and reverse current of any polarity.

The electrodes differ not only in the composition of the coating and the rod, but also in diameter. The dimensions of the coated rod vary from 1.6 mm to 5 mm in diameter. The thicker the parts being welded, the larger the diameter of the electrode required for their fusion. There are mathematical formulas for calculating the diameter for a given thickness of metal parts. It is easier for a novice welder to use tables.

Secondary factors influencing is the type of connection of the parts (horizontal, vertical or overhang welding, butt or fillet weld). From the table data it can be seen that the electrode diameter for corner connection differs slightly from the diameter for butt welding of parts.

At the same time, large-diameter welding rods are not used for welding overhanging surfaces. For ceilings, their sizes are limited to a diameter of 4 mm.

Varying the diameter of the rod while maintaining all other parameters can strengthen or weaken the specific welding current (current per unit cross-section of the electrode). This will affect the penetration depth and thickness of the weld. If the electrode is thinner, the current is concentrated and melts deeper, resulting in a narrow weld. If the electrode is thicker, the specific current strength decreases, and the penetration depth becomes smaller and the weld width becomes larger.

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How to choose the welding current value and its polarity?

The current strength determines the depth of metal penetration. The stronger the current, the more powerful the arc, the deeper the metal melts. The current strength is directly proportional to the diameter of the electrode and the thickness of the weld. It can be determined by calculations using formulas or using ready-made tables.

The current strength is affected by the location of the weld. The maximum current value is used to melt horizontal surfaces. In order to weld vertical seams, the current strength is 15% less, for overhanging (ceiling) joints - 20% less.

A household inverter has a current scale of up to 200 A. In semi-professional models, the scale value is graduated higher, up to 250 A.

Figure 3. Electrode movement during welding.

Polarity is the direction of current flow. The inverter makes it possible to change the direction of the current. How is this done and why is polarity changing necessary?

The flow of electrons (current moves from minus to plus) in inverter welding moves from the “-” terminal to the “+” terminal. The terminal to which electrons arrive (“+”) warms up more. This fact is used to ensure high-quality welding on various metals, with different thicknesses of elements. If the parts are massive, then the “+” terminal is attached to them metal surface(to one of the details). This connection is called direct polarity and is more often used in welding.

If fused thin sheet steel or a high-alloy alloy that is prone to burning out of alloying elements, then the “-” terminal is connected to them. The resulting polarity is called reverse. With such current movement, maximum heating occurs in the electrode, and the base metal heats up less.

Reverse polarity is characterized by greater stability of the arc, it is easier to ignite and maintain its combustion.