How to choose the right current when welding with an inverter

Polarity when welding with an inverter

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When performing welding work, the main attention is paid to connecting the parts being joined. This factor largely depends on the correct settings of the welding equipment.

When working with semi-automatic machines, you should adjust not only the current strength, but also set the desired polarity when welding with an inverter.

The default settings do not allow you to fully solve the assigned tasks, especially when it comes to rare materials or high-alloy steels. Nevertheless, any inverter can be configured in the desired mode and get a high-quality seam.

How does forward and reverse polarity affect welding?

The very concept of polarity, in relation to welding equipment, means one or another connection option associated with current processes and the need to solve a specific problem. In order to change the polarity, you just need to swap the connection terminals. The current will change its direction and the physical processes, and the welding itself will proceed differently in each case.

There are two types of polarity that can be adjusted before performing work:

• Straight polarity. Installed on the equipment before joining thick workpieces with deep seams. In this case, the electrode is connected to the negative terminal, and the metal being welded is connected to the positive terminal. Due to straight polarity, so-called anodic and cathode spots appear during the welding process. A hotter anode spot appears on the workpiece side. Due to this, the base metal is melted to a great depth, making it possible to weld cast iron, aluminum and other workpieces made of complex metals.
• Reverse polarity. With this connection, the plus is connected to the electrode, and the minus is connected to the metal workpiece. An anode spot with an increased temperature appears on the opposite side, that is, on the electrode. The metal remains relatively cold, but the electrode heats up. This joining method allows you to weld thin-walled workpieces.

In accordance with specific tasks, the welder adjusts the forward and reverse polarity when welding with an inverter. Some young specialists do not know all the specifics of setting, so they sometimes have difficulty heating and melting workpieces made of different materials. It is recommended to first study the technical documentation of inverter welding and test the theory with practical actions.

Specifications for polarity selection

The polarity of the connection is selected based on the technical conditions necessary to solve a specific problem. By changing the connection type, it is possible to obtain a concentration of the anode hot spot either on the workpiece itself or on the electrode. Direct heating is carried out due to the positive terminal, so direct connection to it leads to heating of this area.

This connection feature makes it possible to select the operating mode taking into account the following factors.

Thickness of metal workpiece

When welding parts with medium and large thickness, you should use a direct connection. In this case, thermal energy is concentrated on the product itself, helping to obtain a deep weld.

In the same mode, it is possible to cut metals, regardless of their thickness. For welding thin sheet metals, it is recommended to use reverse polarity, where the main heat is concentrated on the electrode.

Due to this, it is possible to avoid overheating of the workpieces, and the melting of the electrode will occur much faster.

Types of metals to be welded

The ability to change the location of the anode heat spot allows you to select the operating mode that is most effective for a specific part.

For example, when welding cast iron or stainless steel, reverse polarity is used when welding with an inverter so as not to overheat the alloy and form a reliable connection. Aluminum, on the contrary, needs to be welded in direct connection mode in order to overcome the oxidative film as quickly as possible.

There are recommendations for setting up equipment for specific alloys, which should be carefully studied and used in practice.

Type of welding wire or electrode

These components also differ in their individual temperature regimes, which largely depend on the fluxes used. If welding is performed with carbon electrodes, then connecting in reverse polarity mode is not suitable, since the flux will be subject to severe overheating and the electrode will become unsuitable for work. In such cases, choosing the most appropriate settings depends entirely on the type of flux and wire.

Sometimes the metal and electrodes require completely different settings, and the welder has to select the most optimal combination of work cycles and amperage. In addition, it is necessary to take into account the manufacturer’s recommendations reflected in the technical documentation.

Features of welding with direct and reverse polarity

The direct and reverse polarity of the inverter have individual properties that must be taken into account when performing welding work.

Features of welding when connecting an inverter with direct polarity:

• Electrodes and filler materials melt during operation and are transferred into the weld pool in the form of large metal drops. This leads to increased metal spattering and an increase in the penetration coefficient.
• The direct connection mode is characterized by instability of the electric arc.
• On one side of the workpiece, the depth of welding is reduced, and on the other, the amount of carbon introduced into the metal mass of the part is reduced.
• The metal is heated correctly, its structure is not damaged and remains unchanged.
• The welding wire or electrode heats up less, which makes it possible to increase the current if necessary.
• Certain welding materials are characterized by an increased deposition rate, especially when consumable electrodes are used in active and inert gases. The same effect is obtained when additives interact with certain types of fluxes.
• Straight polarity during welding affects the structure of the material remaining inside the seam between the welded metal parts. The result is a composition containing manganese and silicon in the complete absence of carbon.

Reverse polarity when welding with an inverter is necessarily used when workpieces made of thin sheet metals are welded. This process requires attention and caution, since there is a high probability of burning and damaging the material. This connection mode is complemented by other methods to avoid inadvertent damage.

Among them are the following:

• A decrease in current strength, causing a decrease in temperature on the surface of the workpiece.
• It is recommended to use an intermittent weld during the welding process. First, several sections are welded in different places, after which they are connected to each other into a single whole. This scheme may vary depending on the specific conditions of the metal connection. In this way, it is possible to prevent deformation of metal workpieces, especially if their length exceeds 20 cm. A larger number of segments makes each section shorter, and the metal warps much less due to this.
• Welding of workpieces that are too thin is carried out with a periodically interrupted electric arc. The electrode quickly leaves the working area and immediately returns to its place and is ignited. The process runs almost continuously.
• When joining with an overlap, the pressure of the workpieces against each other should be as tight and airtight as possible. The presence of even a slight air gap can cause burning of the part located on top. You can create a tight fit using some kind of weight or clamps.
• When making butt joints, it is necessary to ensure a minimum gap between the products being welded. Ideally, there should be no gap at all.
• If thin sheet workpieces have too uneven edges, then a material is placed under the welding joint in this place to compensate for excess heat. Copper or steel plates are best suited for these purposes, the thickness of which should preferably be chosen as large as possible.

For beginners who have just begun to master this type of connection, we recommend training welding with reverse polarity on damaged metal sheets. This will make it possible to feel all the features of the process and in the future avoid burns and other defects.

Source: https://electric-220.ru/news/poljarnost_pri_svarke_invertorom/2019-05-17-1690

How to choose the current for welding with an inverter

Carrying out manual welding using an inverter is gaining increasing popularity among home craftsmen, due to the wide offer of various models with different price ranges.

To connect iron products using inverter welding, a minimum of equipment is required, characterized by its versatility along with low energy consumption and compact dimensions, which further attracts the attention of inexperienced craftsmen.

Learning inverter welding technology for beginners will not be the slightest difficulty.

Operating principle of a welding inverter

A welding inverter is a powerful power supply, which in terms of energy conversion is similar to a switching power supply.

The main stages of energy conversion in the inverter:

1. Reception and rectification of network current with a voltage of 220 V and a frequency of 50 Hz.
2. Converting the resulting rectified current into alternating current with a high frequency from 20 to 50 kHz.
3. Stepping down and rectifying high frequency alternating current into currents ranging from 100 to 200 A and voltages from 70 to 90 V.

Converting high-frequency electric current to a current of the required value allows you to get away from the inconvenient dimensions and heavy weight of the inverter, which are found in conventional transformer devices, in which the current value is achieved by converting the EMF in an induction coil.

Also, when the welding inverter is connected to the network, there will be no sharp jumps in electrical energy, and moreover, the device contains in its circuit special storage capacitors that protect the machine when welding during an unexpected power outage and allow the inverter arc to be ignited more gently.

Obtaining a high-quality weld when welding depends on many factors, therefore, before starting work, the master must familiarize himself with how to properly use the inverter according to the attached instructions, as well as the basic rules and nuances of performing welding work, which will be described in detail below.

Particular attention should be paid to the diameter of the welding electrodes. It is important to know that the amount of energy consumed directly depends on the thickness of the welding rods, and, accordingly, the larger their diameter, the higher the energy consumption.

This information will help to correctly calculate the maximum electrical energy consumption of the inverter, which will prevent adverse consequences from its operation as reflected on household appliances.

There is also a dependence of the diameter of the electrode on the current selected for the work, a decrease in which will lead to deterioration in the quality of the seam, and an increase - to an excessive combustion rate of the welded rod.

Inverter design for welding

In order to understand how to properly use a welding machine, a novice master should familiarize himself with the design of the inverter.

The welding inverter is a metal box with internal components, a total weight of about 7 kg, which is equipped with a handle and a shoulder strap for ease of carrying. The housing of the welding inverter may contain ventilation holes that promote better air outflow when cooling the unit.

The front panel has buttons for switching the operating state, knobs for selecting the required voltage and current, outputs for connecting work cables, as well as indicators indicating the presence of power and overheating of the inverter during welding.

The cable for connecting the device to the power supply is usually connected to the connector located on the back of the inverter.

When the electrode comes into contact with the metal plates being welded during welding, a high-temperature arc is formed, as a result of which both the elements of the welded rod and the metal of the welded joint melt. The bath formed in the arc area by the molten metals of the plates and electrode is protected from oxidation by a liquefied coating of the electrode.

After complete cooling of the metal, the upper surface of the seam, protected by electrode coating during welding, will turn into hardened slag, which can be easily removed by light mechanical action (for example, tapping). It is important to maintain the same distance-gap between the metal of the welded joint and the electrode (arc length), which will prevent its extinction.

To do this, the supply of the electrode to the fusion area must be carried out at a constant speed, and the guidance of the welding rod along the weld joint must be smooth.

Safety precautions

Before starting home welding, the electric welder needs to take care of safety precautions:

• wear a protective suit made of durable, high-density natural fabric that is not subject to fire and melting when sparks hit it. The suit should cover the neck area and have sleeves that fasten tightly at the wrist.
• protect your hands with mittens made of rough fabric;
• wear comfortable leather shoes with thick soles;
• Protect your eyes with a welder's mask with a light filter that depends on the current strength during welding.

The place where welding will be carried out must also be carefully prepared:

• a wooden flooring has been laid, which performs a protective function against possible electric shock;
• the welding site is cleared of anything unnecessary (to prevent welding splashes);
• lighting must be of high quality;
• The welder's movements should not be constrained.

Basics of welding with an inverter

Learning to weld with a welding inverter is not difficult. The very first stage of mastering welding techniques will be preparing the metal plates to be welded:

• cleaning the edges of the plates from traces of corrosion with a wire brush;
• degreasing the edge with a solvent.

Relying on the diameter of the electrodes, the choice of which is based on the grade of the metal being welded, it is necessary to select the current value for welding. The value of the welding current will also be determined by the cross-section of the elements being welded. To ensure that the quality of the seam is not affected when welding with an inverter, the pre-welded rods should be dried in an oven with a heating temperature of 200 º for 2-3 hours.

In order to weld metal, the ground terminal must be connected to the plane of the element being welded. Next you need to ignite the arc. You can do this in two ways:

• striking the metal surface of the plate, similar to igniting a match head;
• tapping the electrode on the surface to be welded.

Working with a welding inverter will be more convenient if, when welding, the holder cable is pressed to the body, having first wrapped it around the forearm of the working hand. In this position, the cable will not pull towards the holders and adjusting its position will be more convenient. Therefore, when choosing an inverter, special attention must be paid to the length and flexibility of the cables, because the convenience of the welder will depend on these indicators.

After igniting the arc, the electrode must be moved away from the plane of the metal plate to a distance equal to the length of the arc (approximately 2-3 mm) and welding can begin. To make high-quality welding, you must constantly monitor the length of the electric arc. A short arc (about 1 mm) can cause a welding defect called “undercut.”

This welding defect is characterized by the appearance of a shallow groove parallel to the weld, leading to a decrease in the strength of the weld. A long arc is unstable, provides a lower temperature in the welding zone, and, as a result, such a seam has too small a depth and is “smeared”.

A welder who knows how to properly adjust the arc length will receive a high-quality weld.

After welding is completed, you should carefully beat off the scale that has frozen on top of the seam with a hammer.

Polarity when welding with an inverter

Melting of the metal is caused by exposure to the high temperature of the welding arc, which occurs as a result of connecting the opposite terminals of the inverter to the metal plate and to the welding rod. Depending on the order of connecting the welding inverter terminals, a distinction is made between direct and reverse polarity.

Polarity is the setting of the direction of electron movement. Both direct and reverse polarity are used when welding with an inverter, so it is important for a novice welder to know the differences between these types of connections.

Straight polarity is the polarity that occurs after connecting the electrode to the minus terminal and the metal plate to the plus terminal. With this connection, the current flows from the electrode to the metal, as a result of which the metal heats up more intensely, and the melting zone becomes sharply limited and deep. The direct polarity of connecting the welding inverter is selected when welding thick-walled elements and when inverter cutting.

Reverse polarity is characterized by connecting the “minus” to the metal plate, and the “plus” to the electrode. The fusion zone with this connection is wider and has a shallow depth. The direction of current is directed from the metal workpiece to the electrode, resulting in greater heating of the electrode. This procedure reduces the risk of burn-through and is used when welding thin-walled metal products.

Working with thin metal

Welding of thin-walled metal products with an inverter is carried out by connecting the terminals according to a circuit corresponding to reverse polarity and placing the electrode at an angle forward. This welding technique provides a smaller heating zone with sufficient seam width.

Ignition of the electrode should be done extremely carefully, because the beginning of the pool when welding thin metal is often accompanied by a burn-through. Welding thin metal with an inverter must be carried out gradually, welding small areas with a short-term removal of the electrode from the bath. At this moment, you need to make sure that the yellow glow of the electrode tip does not go out.

The quality of the weld directly depends on the quality of the electrodes, which will help avoid excessive formation of slag in a small-section weld. Also, the use of small-diameter electrodes avoids burning through the metal.

When completing a weld, you should not abruptly tear off the electrode to extinguish the arc, because in this case a noticeable crater will form at the end of the seam, which will worsen the strength of the metal of the welded joint and the result of the welding equipment will be unsatisfactory.

Another defect that often occurs when welding thin metal is deformation of the product. To prevent its occurrence, it is necessary to carefully secure the parts being welded before welding.

Tips for novice welders

A welder with little experience often wonders how to properly weld metal using electric welding. General tips for working with an inverter and rules for welding metal with an electrode will be given in the section below.

When welding metal with an inverter, you must carefully monitor that the weld is flush with the metal. An electric arc penetrating the metal with intense speed and sufficient depth causes the pool to move backward and creates a weld that can become defective if the speed of the electrode is too high. An ideal seam will be obtained if the electrode performs zigzag and circular vibrations.

When changing the direction of movement of the electrode, remember that the bath follows the heat. The formation of an undercut occurs against the background of insufficient metal of the electrode, so it is worth strictly monitoring and controlling the boundaries of the bath.

By placing the electrode at a certain angle, you can control the direction of movement of the bath, while the vertical position of the electrode will contribute to sufficient penetration. The bathtub in this position will be pressed down and have good boundaries, and the seam will have less convexity. Too much tilt of the electrode will not allow you to control the bath.

Inverter welding is also applicable when performing pipe welding work. Welding takes place under rather difficult conditions, so it is necessary to pay great attention to the quality of penetration at rotary joints. An angle of 30º is the standard angle of inclination of the electrode to the pipe surface.

On pipes made of low-alloy steels with a wall cross-section up to 12 mm, the seam will be single-layer. For pipes with a larger wall thickness, a second weld should be applied, which will increase the overall strength of the weld. After each new weld, it is imperative to clean the hardened slag.

Pipes with a diameter of up to 0.5 m must be boiled continuously.

An inverter is a simple welding machine that is ideal for a novice welder to carry out welding work at home. When choosing an inverter, you must rely on your own needs and the compliance of the selected device with them, thus meeting your needs.

Source: https://www.novaso.ru/svarka/kak-podobrat-tok-dlya-svarki-invertorom.html

How to choose the right current when welding with an inverter

Welding of metal products is used when it is necessary to obtain a high-quality permanent connection characterized by increased strength.

In this case, metals are connected to each other at the molecular level; electrodes are used to perform such welding, which directly affect the quality of the connection made.

When performing welding work, you should correctly select the welding current indicators depending on the electrode used and its diameter. The quality of the work performed largely depends on this, so the welder needs to correctly calculate the ratio of power and electrode diameter.

Welding modes

Modern inverter welding machines allow you to change the current strength, which in turn makes it possible to work with metals of different fusibility characteristics. When choosing a specific welding mode, the following factors should be considered:

• Electrode brand.
• Its diameter.
• Electrode position during welding.
• Type and strength of current.
• Number of layers in a seam.
• Current polarity.

Simply put, current indicators are selected based on the diameter of the electrode. Such a rod, in turn, should be selected for a specific brand of metal elements that are used in the work. It is also necessary to take into account the position when performing welding.

So, for example, if work is performed in a vertical position, it is necessary to reduce the number of Amperes from the nominal by 20%. This will prevent molten metal from draining from the seam.

Remember that the maximum rod diameter for ceiling welding is 4 millimeters.

Selecting the correct current for welding

The diameter of the rods for working with an inverter or classic welding machines is selected depending on the thickness of the parts being welded. If you need to weld a surface of 3-5 millimeters, then you should choose a rod diameter of no more than 4 millimeters. For an 8 mm working seam, an electrode with a thickness of 5 mm will be sufficient. In this case, for each of these rods it is necessary to select the correct current strength.

When working with a 3 mm electrode, the current indicators are in the range of 65-100 Amperes. The choice of a specific current indicator in this case depends on the welding position and the type of metal. Experienced welders advise using an average value of 80 Amps.

When working with 4 mm electrodes, it is necessary to set the current strength to 120-200 Amperes. It should be said that 4 mm rods are most widely used today, as they are suitable for working with small and medium-sized seams.

Varieties of electrodes with a thickness of 5 millimeters will require the use of a current of 160-250 Amperes. It should be said that inverters capable of operating with such voltage are classified as professional. They guarantee deep welding and excellent joint quality.

Electrodes 6-8 millimeters thick require a current of 250 Amperes. In some cases, when working with refractory metal alloys, it is necessary to use a current value of 350 Amperes.

It must be said that the use of inverters made it possible to perform high-quality welding even with the use of thin electrodes. That is why today rods with a thickness of 1 to 2 millimeters are increasingly used.

To work with them, a current of 45 Amps will be sufficient.

Note that for high-quality performance of such welding, the inverter must have the function of smoothly adjusting the current, since sharp jumps and minimal errors can have a significant impact on the quality of the weld.

Recommendations

Modern welding inverters allow you to set the voltage completely automatically. You will only need to indicate the thickness of the electrode used, and the inverter automation will set the current indicators automatically. All this allows us to significantly simplify welding, while simultaneously improving the quality of such work.

Source: https://steelfactoryrus.com/kak-pravilno-vybrat-tok-pri-svarke-invertorom/

We study direct and reverse polarity when welding

The direction of electron flow is controlled by polarity by switching the wires to the plus or minus terminal. That is, when working with DC welding, two settings are possible:

1. Straight polarity. The minus is connected to the electrode, the plus is on the ground terminal. In this case, the current moves from the electrode to the workpiece, and the metal heats up more.
2. Reverse polarity. The plus is connected to the electrode, and the minus to the ground terminal. The movement of current from minus to plus (from the workpiece to the electrode) creates more intense heating.

Direct and reverse polarity of connection when welding with an inverter is used depending on the tasks assigned and the quality of the materials. With alternating current, the type of connection is not important, but with direct current, it is possible to change the polarity manually.

Polarity value for welding

Direct current creates a thermal (anodic) spot. By changing the polarity, you can move it from the electrode to the workpiece. The main heating is created on the positive socket, therefore, with direct polarity, the workpiece heats up more, and with reverse polarity, the electrode heats up more. In this way, the capabilities of the inverter are formed depending on the characteristics of the metals:

• Metal thickness. With direct polarity, the main heat goes to the workpiece, so the width of the weld joint is quite deep. Accordingly, for thin metals it is more correct to use a reverse connection, in which the metal heats up less than the electrode.
• Metal type. When welding, you have to work with various alloys that have certain properties. For example, aluminum is a medium-melting metal, so you need to provide the workpiece with a direct connection for heating. It is better not to overheat stainless steel by choosing reverse polarity. The inverter settings allow you to take into account what kind of alloy is being cooked, so a preliminary study of the instructions will help you cope with the task effectively.
• Electrode type. Welding electrodes are coated with flux. When heated, it burns, fulfilling its main task: displacing air and preventing the formation of pores. The type of flux determines the features of using electrodes at different temperature conditions. For example, carbon electrodes are not suitable for connections with reverse polarity. The manufacturer's recommendations will help you make the right choice. The same applies to wire types. By the way, inverter semi-automatic machines also have characteristics that are worth taking into account.

If the workpiece and the electrode have characteristics that require conflicting settings, a compromise will have to be found by adjusting the current strength and weld processing time. With experience comes knowledge that allows you to solve any problem.

Manual arc welding using a consumable electrode (MMA)

Here its role is played by a special melting wire covered with slag. The method is very popular, but experts consider it not the best option for obtaining high-quality seams if the product is a complex alloy in composition. During melting, the wire connects the necessary parts, and its coating removes dirt and protects the weld pool from oxygen. The method is suitable for welding cast iron and ferrous metals.

Semi-automatic welding

The electrode is a wire that automatically enters the welding zone.

The device is in manual movement mode, so this method is not suitable for processing a large working area; it is used for welding thin sheets, non-ferrous metals, and high-alloy steel. Both direct and pulsed current are used.

When using flux-cored wire, gas is not needed; in other cases, current welding is carried out in an environment of active or inert protective gases. It is possible to weld with an electrode without melting it.

Gas shielded welding

The technological process involves the use of argon gas, which burns away dirt and oxygen compounds. The electrode is an infusible tungsten or graphite rod. The use of argon cleanses the weld pool from all unnecessary impurities and oxides. The formation of slag is excluded, the seam is high-quality and clean, but welding in a shielding gas environment is a rather expensive technology that requires serious skills.

Different types of welding are used and depending on the welding operating conditions. For example, to repair car bodies, services use semi-automatic arc welding using a shielding gas environment, which makes it possible to create high-quality welding work at a low cost. Direct and reverse polarity when welding with an inverter allows you to adjust the melting depth for any type of welding work.

Manual arc welding technology

Arc welding is the most common type of metal welding. The method is universal, technologically simple and allows you to obtain good quality welds in non-production conditions. The electric current of the welding source forms an arc between the workpiece and the electrode. The coating (flux) burns on it, releasing a gas that cleanses the work area of ​​oxygen.

According to the shape and types of connections, welding seams are divided into:

• T-bars;
• corner;
• butt;
• overlap;
• end

Different angles of inclination of the electrode allow you to create different types of seams. The most convenient interval is between 45 and 90 degrees, at which the weld pool is completely visible. With experience comes an understanding of exactly how to change the angle of inclination.

Typically, welding machines are equipped with a ground cable with a clamp-type holder. At first glance, it is convenient; such a device can be securely attached to almost any surface (sheets, rolled metal, etc.). But there are situations when it is not possible to install such a mass on the workpiece or, even more often, it burns out. A good alternative would be the magnetic contact of the welding cable.

Bottom line

The task for a beginner is to learn how to “make” a weld. The base metal is heated to the point of melting, forming a weld pool. Depending on the situation, the welder changes the current settings, focusing on the condition of the bath. You need to start with the settings recommended by the manufacturers, and then gradual practice will help you understand and correctly use all the capabilities of the inverter.

Source: https://electrod.biz/apparat/polyarnost-pri-svarke-invertorom.html

Alloys of non-ferrous metals, their composition and application - Metals, equipment, instructions

Copper, nickel, lead, zinc and tin are called heavy metals. This name arose during the period of industrialization of the country in connection with the concept of “heavy industry” and its significance for the development of the national economy. At the same time, this name successfully distinguishes heavy metals from the equally important aluminum and other light metals that have a lower density.

The conditional boundary between heavy and light metals is considered to be a density of 5000 kg/m3. In foreign languages ​​there are no similar names that summarize these groups of metals; however, their importance in technology is everywhere recognized as paramount after iron.

Iron has long been the main material for building structures, mechanical engineering and transport. However, already in the 19th century. With the development of new industries and technology, some of its shortcomings came to light.

Of course, we are not talking about pure iron, but about its industrial alloys - cast iron and steel.

Possessing a wide variety of valuable properties, ordinary cast iron and steel are at the same time insufficiently resistant to corrosion in air and especially under the influence of water, solutions of salts and acids, have little thermal conductivity, little electrical conductivity and have a fairly high coefficient of friction.

Heavy non-ferrous metals and their alloys have been used since the beginning of the 19th century. became iron substitutes in those industries that required special properties that were not sufficiently expressed in cast irons and steels.

Copper

Copper has high electrical and thermal conductivity. In terms of these properties, it is second only to silver. The ductility of copper allows it to be easily processed by rolling, stamping and drawing. With the development of electrical engineering, copper has become the main material for wires, busbars, contacts and other conductive products.

The high thermal conductivity of copper allows it to be used in all kinds of devices that conduct heat - in heaters and refrigerators. In the chemical industry, copper is used to make coils for heating or cooling solutions, digesters, pipelines and other equipment parts.

Even small impurities of other elements greatly reduce the electrical conductivity, thermal conductivity and corrosion resistance of copper. To fully utilize these properties, a metal containing no more than 0.05% impurities is required.

However, pure copper is too soft for building structures, machine parts and fittings. Its alloys with other metals have significantly greater strength and hardness, many of them are superior to copper in other valuable properties, for example, corrosion and anti-friction.

Copper alloys with 10–40% Zn - brass is cheaper than pure copper. At the same time, they are well processed by pressure and cutting, are more durable, hard and resistant to corrosion.

Small additions of iron, aluminum and manganese in various combinations give brass even greater strength and hardness, and additives of tin, aluminum, manganese and nickel enhance anti-friction properties.

In the form of sheets, rods, pipes and various castings, brass is widely used in chemical and general engineering, shipbuilding and military equipment.

Previously, only copper alloys with 6–20% Sn, known for their high mechanical properties, corrosion resistance and antifriction, were called bronzes. Later, due to the scarcity of tin, they learned to produce similar alloys by adding other metals to copper.

Now, in addition to tin bronzes, aluminum (5–11)% Al, lead (25–33)% Pb, silicon (4–5)% Si, beryllium (1.8–2.3)% Be, cadmium bronzes are widely used up to 1% Cd, etc.

All of these alloys contain small amounts of secondary alloying components that enhance certain properties of copper.

Each type of bronze is valuable in its field of application: aluminum bronzes with lead additives are needed for bearings, and beryllium bronzes are used for the manufacture of springs.

Brasses and bronzes, like many other alloys, are divided into cast and wrought, suitable for casting or for processing by pressure, rolling, forging, stamping, drawing.

Copper-nickel and copper-nickel-zinc alloys: cupronickel (5–35% Ni) and nickel silver (5–30% Ni and 13–45% Zn) are especially resistant in aggressive environments containing active chemicals. In the form of tape, sheets and wire, these alloys are used for the manufacture of medical instruments, precision mechanics products, cutlery, household and artistic products.

Copper has been known since ancient times - the Bronze Age was a period of rapid development of material culture. Subsequently, bronze was replaced by cheaper and more accessible iron. With the emergence of large-scale industry, copper production and consumption began to increase rapidly again.

Until 1958, copper occupied the first place among non-ferrous metals in terms of global production. Now it is inferior to aluminum in this regard, but still remains a scarce metal that requires substitutes. In electrical engineering, some copper began to be replaced with aluminum - less electrically conductive, but lighter.

This is beneficial: the consumption of aluminum by weight is almost half that of copper. In railway transport, copper and bronze are partially replaced by zinc alloys. In military technology, cartridge cases began to be made of steel instead of brass and they were only covered with a layer of brass - clad.

Replacing copper with other, less scarce metals and alloys is an important problem of our time.

Nickel

Compared to other heavy non-ferrous metals, nickel is the most durable, hard, refractory and resistant to corrosion. Like iron and cobalt, it is ferromagnetic. Pure nickel is ductile and easy to process.

Nickel is relatively expensive, and its consumption in pure form is low. To protect against corrosion and for decorative purposes, products made of iron, aluminum, magnesium, zinc and other metals are coated with a thin layer of nickel (nickel plating). In the form of sheets, pipes, and wire, it is used for special products for chemical production - parts of equipment and devices.

Nickel is also required for the production of alkaline batteries - iron-nickel and nickel-cadmium. These batteries are lighter, more compact and more reliable in operation than lead batteries. Nickel catalysts are used in many chemical technology industries.

More than half of all nickel is consumed in alloys with iron.

Strong and wear-resistant nickel cast irons containing chromium, molybdenum and copper are needed for the production of powerful internal combustion engines for locomotives, special machines and dies.

Many nickel alloys are heat-resistant: they do not oxidize in air at high temperatures. These include alloys EI, Inconel, Nimonic, Gastelloy, etc., capable of operating at temperatures up to 600 °C. They are used for the production of jet turbines, gas turbine units and in nuclear reactors.

Nichrome (75–85% Ni, 10–20% Cr, the rest iron) and other similar thermoelectric nickel alloys are not only heat-resistant, but also have high ohmic resistance and are used for wire or tape heaters.

A highly magnetic alloy of nickel with iron (permalloy) and other alloys similar to it are used in electrical engineering and radio engineering.

Of the alloys of nickel with non-ferrous metals, copper-nickel alloys are the most important; they have already been discussed above.

The first metallic nickel was obtained in Sweden in 1751, and its production for sale began only in 1825. For a long time it remained insignificant. Many of the valuable properties of nickel were not known until the beginning of the 20th century, so it was only in the 20th century that the demand for this metal began to grow rapidly.

Now nickel consumption in all countries is strictly taken into account and measures are taken to use it economically. To achieve this, more and more of the nickel in stainless steels is being replaced by chromium, and conventional steels are being coated with a thin layer of stainless steel (cladding).

Lead

Lead has been known since ancient times - at least two millennia BC. e. At that time, the easy machinability of soft lead and its high density were especially valued. Coins, jewelry, various vessels, water pipes, projectiles for slings and catapults were made from lead. With the invention of gunpowder, lead was used to make buckshot, bullets and shot.

Lead's resistance to dilute sulfuric and hydrochloric acids and many other reagents made this metal a popular choice in the 19th century. the main material of the then emerging chemical industry. Lead is easily rolled. Sheet (rolled) lead with a thickness of 2 to 10 mm is convenient for covering equipment and protecting it from corrosion.

The sheaths of cables intended for long-term operation underground, in water or in a humid atmosphere are now made from lead, adding small amounts of other metals to it for greater ductility.

Lead-acid batteries are still needed to ignite internal combustion engines, despite the advent of nickel batteries, which are significantly more expensive. About half of all lead is spent on the production of cables and batteries.

In nuclear technology, lead serves as protection against γ rays, which it absorbs better than many other materials.

In military affairs, lead is still needed for the manufacture of shrapnel and core bullets.

Lead alloys differ from pure metal either in greater strength and hardness, or in anti-friction; Most of them are also resistant to corrosion.

Alloys with a low coefficient of friction - babbitts (after the name of the inventor Babbitt) - are divided into tin-bearing and tin-free. The former contain, in addition to lead, tin, copper, antimony, cadmium, nickel and tellurium, and the latter contain sodium, calcium, tellurium and other elements. Babbitts are low-melting, they are poured in liquid form into bearing shells or applied as a layer on a steel strip.

In the chemical industry, alloys of lead and antimony are often used - they are hard and resistant to corrosion.

In alloys for soldering - solders, lead is partially replaced by more expensive and scarce tin.

Demand for lead constantly outstrips its production. Therefore, in modern industry, new ways to save lead are being outlined. They are now trying to replace the lead sheaths of some cables with plastic ones, and anti-corrosion coatings with synthetic organic materials. Printing lead alloys can sometimes be replaced with zinc alloys, and in the future - with plastics, when plastics with good casting properties are obtained.

Zinc

Information about the history of the development of zinc production is varied. According to some of them, this metal was produced in India and China back in the 5th century. Industrial production of zinc in Europe arose only in the 18th century. in England, then in Upper Silesia.

Currently, about half of the zinc produced is used to coat iron to protect it from corrosion. A thin layer of zinc is applied to the iron using a hot method or electrolysis.

The electrolytic coating is thinner and zinc is consumed more economically; however, due to more complex equipment, hot-dip galvanizing is still used more often than electrolysis. Zinc reliably protects iron from corrosion in air and cold water.

Galvanizing is much cheaper than coating with tin - tinning or nickel - nickel plating.

Another important area of ​​zinc consumption is the production of alloys, including the already familiar brass and nickel silver.

Zinc-based alloys partially replace bronze and babbitt in bearings. These zinc alloys contain 8–11% aluminum, 1–2% copper, and 0.03–0.06% magnesium. The same components, but in different proportions with zinc, are contained in typographic alloys, similar in properties to lead-antimony alloys.

Compared to other non-ferrous metals, zinc is cheap, and its resources in known deposits are quite large. Therefore, the problem of replacing zinc with other metals did not arise. With the increase in aluminum production and a decrease in its cost, it may be advantageous to coat iron not with zinc, but with aluminum - aluminizing.

Source: https://spb-metalloobrabotka.com/kak-pravilno-vybrat-tok-pri-svarke-invertorom/

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 ensures good quality of the seam.

The welding electrode consists of a core and a protective coating

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 ignite very poorly in high humidity (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 that come 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, you can dry them in a regular 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.

Coating (protective coating) of electrodes can be: basic, rutile, cellulose and acidic.

Types of coating and their characteristics

There are only four types of coatings:

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.

There are more than 200 brands of electrodes for welding, about 100 of them can be used in manual arc welding

The other two (rutile and acidic) can work with both alternating and direct current when welding. But acidic coating is very toxic: you can work indoors only if the workplace is 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; how to choose an inverter welding machine, read here.). 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:

They are recognized by many as the best electrodes for beginners who work with inverter welding machines: they are easier to work with, at the same time, they allow you to weld high-quality seams even without 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.

Diameter of electrode LEZ MR-3, mmLength, mmRecommended welding current, АWeight of pack, kgPrice, 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

Source: https://crast.ru/instrumenty/kak-podobrat-tok-dlja-svarki-invertorom

We select the welding current depending on the specific diameter of the electrodes

Welding of metal products is used when it is necessary to obtain a high-quality permanent connection characterized by increased strength.

In this case, metals are connected to each other at the molecular level; electrodes are used to perform such welding, which directly affect the quality of the connection made.

When performing welding work, you should correctly select the welding current indicators depending on the electrode used and its diameter. The quality of the work performed largely depends on this, so the welder needs to correctly calculate the ratio of power and electrode diameter.

What does straight polarity mean?

In order to achieve a high-quality seam when welding various steels, it is important to know which polarity is suitable for the material that needs to be processed. The general essence of welding with an inverter is that the machine must have “+” and “-“ sockets. Depending on which socket the ground will be connected to and which the electrode will be connected to, the polarity will depend.

Direct polarity is connected in this way: a ground is added to the positive socket, and an electrode is added to the negative socket. It is important to know here that the type and polarity of the current will be determined by the existence of the anode and cathode spots. During straight polarity welding, an anodic spot, which is hotter, will form on the workpiece side.

What does reverse polarity mean?

With reverse polarity, it is logical that the connections of the ground and the electrode are swapped. That is, an electrode is connected to the positive socket, and ground is connected to the negative socket. Here you need to understand that when connecting the sockets in this way, an anode spot will also form, but it will appear not on the side of the workpiece, but on the opposite side from it, that is, on the electrode.

Important note! Connecting the polarity manually is carried out only when welding with an inverter, that is, in the presence of direct current. When carrying out the same process, but on alternating current, the polarity is changed up to hundreds of times per second independently. Therefore, the connection method does not matter.

As you can see, the difference between direct and reverse polarity when welding with an inverter is that the anode spot will form in different places.

Polarity selection criterion

When changing the connection, the specialist changes the location of the heat concentration, transferring it either to the workpiece or to the electrode itself. It is important to know here that the socket with a plus is responsible for heating, which means that with a direct connection, the maximum temperature will be observed at the welding seam. When connected in reverse, the maximum temperature is spent on heating the consumable element. Knowing this feature, you can independently choose the connection diagram based on such a parameter as the thickness of the material.

The choice between forward and reverse polarity when welding will greatly depend on the thickness of the metal product. If this parameter has a medium or high value, then it is best to resort to straight polarity. This is explained by the fact that strong heating of the workpiece will provide a deeper seam, which, in turn, will improve the quality of the weld. Straight polarity is also used when cutting pieces of metal.

And, on the contrary, when welding thinner metal workpieces, it is recommended to use a reverse connection, since the material will not overheat too much, but the electrode will melt much faster.

Metal type

Forward and reverse polarity when welding will also depend on the type of metal product that needs to be processed. It is important to understand that the ability to independently change the type of connection affects the efficiency of working with various types of workpieces. An example is welding stainless steel or cast iron.

When working with such materials, it is best to use reverse polarity, which will avoid severe overheating of the raw material, which will eliminate the need to create a refractory welded joint. But, for example, when working with a type of metal such as aluminum, it is best to use straight polarity when welding. Since with low heating it will be very, very difficult to break through the oxides of this raw material.

Most often, each material has a recommendation that states what type of polarity is best to process this workpiece.

Types of electrode and wire

Another very important detail that must be taken into account when welding with a direct or reverse polarity inverter is the type of electrode, which, like metal, has its own characteristics at different temperature conditions. Most often, the parameters are related to the type of flux used in the base of the consumable. Let's say we have a carbon-type electrode.

It is impossible to use a reverse connection to work with such an element, since too much heating of a consumable of this type will overheat the flux and the product will become completely unusable. You can only use DC welding with straight polarity.

Here, as in the case of metal blanks, in order not to make a mistake, it is best to study the markings and manufacturer’s recommendations for working with each type of consumable separately.

Properties of straight polarity

It is quite obvious that there are advantages to welding with direct and reverse polarity. If we talk about the first type of connection, we can highlight the following points:

• the resulting weld will be quite deep, but at the same time quite narrow;
• used when welding most metal workpieces whose thickness is higher than 3 mm;
• Welding, for example, non-ferrous steel is possible only with a tungsten electrode, as well as with a direct connection to the inverter;
• straight polarity when welding metals also has a more stable arc, which, in turn, ensures a higher quality weld;
• when using a direct connection, it is strictly prohibited to use electrodes that are suitable for welding with alternating current;
• straight polarity has also proven itself in cutting metal workpieces.

Reverse polarity properties

Just as direct polarity during welding has its strengths and weaknesses, reverse connection can also be characterized by certain properties:

• If you use DC welding, but make a reverse connection, the resulting seam will not be too deep, but very wide.
• The best weld quality is achieved only when working with thin metals; if reverse polarity is used to weld thick materials, the weld quality will be too unsatisfactory.
• When welding on a reverse connection, it is strictly forbidden to use electrodes that cannot be overheated.
• If the current strength decreases significantly, the quality of the seam will also deteriorate significantly due to the fact that the arc will begin to “jump”.
• Since reverse polarity is most often used for welding high-alloy steels, it is necessary to be guided not only by the rules of welding with an inverter, but also take into account the requirements of the metal for the duration of the working cycle, as well as for the cooling process of the metal.

After a person has studied in detail the features of welding with direct polarity, as well as with reverse polarity, it becomes quite simple to answer the question of why change it. To briefly summarize, we can say the following:

The use of direct polarity is justified in cases of large metal thickness. Also, this type of connection is justified if non-ferrous metal is welded: brass, copper, aluminum.

It is most important to pay attention to working with aluminum, since its oxide film has a huge melting temperature, which greatly exceeds the melting point of the raw material itself.

In other words, we can say that straight polarity welding is the rough processing and joining of the structure.

The reverse connection, in turn, is used to work with thin steels. In addition, it is used when processing high-alloy or stainless steel. These materials do not tolerate overheating well, and therefore it is impossible to use melting at high temperatures. That is, work on the reverse connection is considered more delicate.

From this we can conclude that the answer to the question of why change the polarity when welding with electrodes is that the quality of the weld depends on it, as well as the performance of the consumable itself, since not all electrodes can be connected in the reverse way.

Conclusion

To summarize all of the above, then using an inverter or semi-automatic welding machine for welding at home is a very common thing. But the correct choice of connection for direct current, as well as knowledge of what material needs to be cooked in what way, is the basic information necessary for the successful completion of the work. If this knowledge is available, then using these tools will not be a problem.

Source: https://respect-kovka.com/kak-pravilno-vybrat-tok-pri-svarke-invertorom/

How to work with welding - basics, technology, choice of current, manual arc welding technique

In a private house, in a country house, in a garage and even in an apartment - everywhere there are many jobs that require metal welding. This need is especially acute during the construction process. Here, especially often, something needs to be cooked or cut off.

And if you can still cut it with a grinder, then there is nothing to reliably connect the metal parts with except welding. And if the construction is carried out with your own hands, then the welding work can be done independently. Especially in places where the beauty of the seam is not required.

We will tell you how to properly weld by welding in this article.

Basics of electric welding

articles

Welded metal joints are the most reliable today: pieces or parts are fused into a single whole. This happens as a result of exposure to high temperatures. Most modern welding machines use an electric arc to melt metal. It heats the metal in the affected area to the melting temperature, and this happens over a small area. Since an electric arc is used, welding is called electric arc welding.

This is not a completely correct way of welding)) At a minimum, you need a mask

Types of electric welding

An electric arc can be formed by both direct and alternating current. Welding transformers use alternating current, and inverters use direct current.

Working with a transformer is more complicated: the current is alternating, so the welding arc “jumps”, the device itself is heavy and bulky. The noise that both the arc and the transformer itself makes during operation is also quite annoying. There is one more problem: the transformer greatly “stresses” the network. Moreover, significant voltage surges are observed. The neighbors are not very happy about this fact, and your household appliances may suffer.

Inverters mainly operate from a 220 V network. At the same time, they are small in size and weight (about 3-8 kilograms), operate quietly, and have almost no effect on voltage.

The neighbors won't even know you started using the welding machine unless they see you. In addition, since the arc is caused by direct current, it does not jump and is easier to stir and control.

So if you decide to learn how to weld metal, start with a welding inverter. Read about choosing an inverter welding machine here.  

Welding technology

For an electric arc to occur, two conductive elements with opposite charges are required. One is a metal part, and the second is an electrode.

The electrodes used for manual arc welding consist of a metal core coated with a special protective compound. There are also graphite and carbon non-metallic welding electrodes, but they are used for special work and are unlikely to be useful to a novice welder.

When an electrode and metal of opposite polarity touch, an electric arc occurs. After its appearance, in the place where it is directed, the metal of the part begins to melt. At the same time, the metal of the electrode rod melts, being transferred with the electric arc to the melting zone: the weld pool.

How a weld pool is formed. Without understanding this process, you will not understand how to weld metal correctly (To enlarge the size of the picture, right-click on it)

During the process, the protective coating also burns, partially melting, partially evaporating and releasing a certain amount of hot gases. Gases surround the weld pool, protecting the metal from interaction with oxygen. Their composition depends on the type of protective coating. The molten slag also coats the metal, also helping to maintain its temperature. To weld properly, you must ensure that the slag covers the weld pool.

The weld is formed by moving the bath. And it moves when the electrode moves. This is the whole secret of welding: you need to move the electrode at a certain speed. It is also important, depending on the required type of connection, to correctly select its angle of inclination and current parameters.

https://www.youtube.com/watch?v=PFhXTomXXSw

As the metal cools, a slag crust forms on it - the result of the combustion of protective gases. It also protects the metal from contact with oxygen in the air. After cooling, it is beaten with a hammer. In this case, hot fragments fly away, so eye protection is required (wear special glasses).

You can read about how to make a barbecue out of a cylinder or barrel here. Just get some practice.

How to learn to cook by welding

It all starts with preparing the workplace. Safety when working with electric welding must be given increased attention: there is a possibility of injury from both electricity and high temperatures. Therefore, take your preparation seriously.

It is more convenient to learn to weld with electric welding on a thick piece of metal: it is better to practice on it. In addition to it and the welding machine, you will need gaiters (thick gloves) and a welder’s mask. You also need thick clothing that protects the entire body, and durable shoes with thick leather. They must withstand sparks and scale. You will also need a hammer and a wire brush to knock off the slag. You will need glasses to protect your eyes.

How to connect the electrode

It will be easier for beginners to carry out welding work if they take a universal electrode with a diameter of 3 mm (3.2 mm, to be precise). They are more expensive, but easier to work with. After you learn how to weld metal, you can try using cheaper ones, but it’s better to start with these.

The electrode is inserted into a holder attached to one of the welding cables. There are two types of clamps - spring and screw. If the electrode holder is spring-loaded, press the button on the handle and insert the electrode into the socket that appears. When screw clamped, the handle rotates. Unscrew it, insert the electrode and clamp it. In any case, it should not wobble. After installing the electrode, you can connect the cables.

There are two outputs on a DC welder: positive and negative. There are also two welding cables:

• one ends with a metal clamp-retainer - it is connected to the part;
• the other is a holder for the electrode.

Which polarity to connect for welding depends on the type of work. If we talk about inverters, then more often the plus is connected to the part, and the minus is supplied to the electrode. This connection option is called direct polarity. But there is a list of works in which reverse polarity is applied: minus to the part, plus to the electrode (for example, for welding stainless steel).

Direct and reverse polarity of connection on the welding inverter

Straight polarity provides better heating of the metal, which is necessary for most connections. This is explained by the fact that electrons move from the negatively charged pole - with straight polarity, this is the electrode - to the positive - part. At the same time, they additionally transfer their energy to the metal, increasing its temperature.

Start of welding: light the arc

We figured out how to connect the electrode to the inverter. Now about how to light an arc. It occurs when there is direct contact between the electrode and the part. There are two ways:

• chirping;
• tapping.

Everything is clear from the name: in one case, you need to run the electrode along the seam (so that there are no marks left), in the second, you need to hit the part with the tip of the electrode several times.

When the electrode is new, its tip is exposed, ignition occurs easily. If it was already in use, a wall of several millimeters of protective coating would form around the rod. This coating needs to be knocked off by hitting the part with the tip several times.

Both methods of ignition are used, here everyone chooses what is convenient for them. This skill is the first one you will have to master if you want to learn how to use electric welding.

Therefore, you take several electrodes, a thick piece of metal, and try to strike an arc. Once you have succeeded, you can proceed to the next stage of training.

Electrode tilt

The main position of the electrode is tilted slightly towards you - at an angle from 30° to 60° (see figure). The amount of inclination is selected depending on the required weld and the set current. Focus on the condition of the weld pool.

The first position is called the “backward angle.” In this case, the bath and molten slag moves behind the tip of the electrode. Its angle of inclination and speed of movement must be such that the slag has time to cover the molten metal. In this position, we obtain heating of the metal to a greater depth.

Manual arc welding technique: positioning the electrode at an angle forward and at an angle backward

There are situations when the metal does not need to be heated very much. Then the angle of inclination changes to the opposite, the seam and the bathtub “stretch” behind the electrode. In this case, the heating depth is minimal.

Electrode movements

The answer to the question “how to properly weld with electric welding” is simple: you need to control the weld pool. To do this, it is necessary to hold the electrode at a distance of 2-3 mm from the metal surface and control the condition and size of the weld pool. This is where the skill of a welder lies.

The difficulty lies in the fact that several parameters have to be controlled simultaneously:

• move the electrode along one of the trajectories shown in the photo,
• as it burns, lower it a little lower, maintaining a constant distance of 2-3 mm;
• monitor the size and condition of the weld pool, accelerating or slowing down the movement of the electrode;
• follow the direction of the seam.

The movements of the electrode tip are shown in the figure. Those who want to learn electric welding for home use do not need to master all of them, but you will need two or three movements: for different situations, seams and metals.

Another element of manual arc welding technique: the tip of the electrode must move along one of these trajectories (or something similar)

How to learn to cook with electric welding? Practice movements on a thick piece of metal. Then you get not seams, but rollers. This stage is the initial one. On it you will master the basic skills of a welder: learn to control the distance from the tip of the electrode to the part, and at the same time, move it along a given path, monitor the weld pool and the slag in it.

To do this, take thick metal and draw a line on it with chalk: you will need to lay a roller along it. You light the arc and begin to master the movements, learning to control the bath at the same time. You won’t succeed the first time, or even the tenth time. You will probably use a dozen electrodes. When the manual arc welding technique has been mastered: the bead is uniform, its width and height are constant (or almost), you can try to connect the parts.

You should get similar rollers. This way you can learn how to weld using electrodes correctly.

Read how to make a gazebo on a metal frame in this article, and here the construction of a shed on a metal frame is described.

How to weld metal correctly

Learning to hold the electrode correctly and move the bath is not enough for a good result. It is necessary to know some of the subtleties of the behavior of the metals being joined. The peculiarity is that the seam “pulls” the parts, which can cause them to warp. As a result, the shape of the product may differ greatly from what was intended.

Electric welding technology: before starting to apply a seam, the parts are connected using tack welds - short seams located at a distance of 80-250 mm from each other

Therefore, before work, parts are secured with clamps, ties and other devices. In addition, tacks are made - short transverse seams laid every few tens of centimeters. They hold the parts together, giving the product its shape. When welding joints, they are applied on both sides: this way the resulting stresses are compensated. Only after these preparatory measures do welding begin.

Read about the types of welds and joints (horizontal, vertical, ceiling) and how to weld them correctly here.

How to choose a current for welding

It is impossible to learn how to weld using electric welding if you do not know what current to set. It depends on the thickness of the parts being welded and the electrodes used. Their dependence is presented in the table.

But with manual arc welding, everything is interconnected. For example, the voltage in the network has dropped. The inverter simply cannot produce the required current. But even under these conditions you can work: you can move the electrode more slowly, achieving good heating. If this does not help, change the type of movement of the electrode - passing over one place several times. Another way is to use a thinner electrode. By combining all these methods you can achieve a good weld even in such conditions.

Now you know how to weld properly. All that remains is to practice the skills. Choose a welding machine, buy electrodes and a welding helmet and start practicing.

To reinforce the information, watch the video lesson on welding.

Source: https://ice-people.ru/svark-2/kak-rabotat-so-svarkoj-azy-texnologiya-vybor-toka-texnika-ruchnoj-dugovoj-svarki.html