What electrode to cut thick metal. Other parameters for evaluating rods

Hand.backed metal cutting of metal: features, methods and technological process of work

Electric driving is unique in that with this method, the metal is swimming in the place where the incision needs to be made. During operation, the molten metal is removed by the power of the arc pressure or flows from its own weight.

Electric cutting is usually carried out manually. For work, it is recommended to use steel electrodes with a thick refractory coating, but tungsten and carbon electrodes can also be used.

For this method of cutting metal, you do not need to have special equipment. Work can be carried out in hard.to.reach places and in any spatial position of the design.

However, when separating the metal, an electric arc cannot be achieved by high quality. It is impossible to ensure the evenness of the edges of the parts and in large quantities there is a secretion of slag. Therefore, for the further use of the obtained metal parts, their mechanical processing is necessary. The performance of this method remains low.

We need to pay special attention to safety measures. The welder must be carefully protected from drops of metal and slag. It is worth providing where the molten metal will drain in order to avoid fire.

Used methods

Electric arc is actively used not only for welding, but also in metal cutting. There are several varieties of arc cutting of metal details: manual arc cutting with melting and non-melting electrodes, as well as air and oxygen-duging cutting.

Arc cutting with non.melting electrode

With this method, the work is carried out both on alternating and on direct current of direct polarity. The current of the current should be 400-800 A. In this case, coal and graphite electrodes are used.

This method is not so widely used. It is used to analyze large metal scrap, making holes and burning of rivets, as well as when dismantling unnecessary metal structures.

The incision is carried out by melting the metal in the required zone, and not by combustion. Thanks to this quality, it becomes possible to work with materials that are not amenable to gas cutting, such as cast iron or highly alloyed steels.

This method does not differ in high accuracy of the work: the width of the section itself is large, and the edges remain uneven. If you use electrodes with a rectangular cross section, you can slightly improve the result of the work.

Arc cutting with a melting electrode

This method allows you to achieve greater accuracy and purity, and the section itself turns out narrower, unlike the previous method. For cutting, the same electrodes are used the same diameter as for welding, while increasing the current strength by 20-30%. When conducting such work in domestic conditions, you can use simple electrodes, but it is recommended to purchase special electrodes with a special coating to improve the work process.

There are two types of coating compositions. First: Manganese ore (98%) and Potash (2%). Second: manganese ore (94%), kaolin (3%), marble (3%). Thanks to this coating, the stability of the arc increases, the inner rod melts more slowly and its insulation from the walls of the cut. The molten metal is oxidized, thanks to the special components contained in the coating, this allows you to accelerate the cutting process.

The production of the above electrodes is made of wire with a diameter of 3 to 12 mm and a length of up to 300 mm. The thickness of the special coating should be 1-1.5 mm. The calculation of current strength is made from the following ratio: 55-65 A per 1 mm diameter of the electrode used.

Air and oxygen-dug cutting

This method of separation of metal parts differs from the previous ones in that the metal melted with an electric arc is immediately blown away by a stream of compressed air or pure oxygen. Usually this method is used to get rid of defects in the welding location and separating blankets made of stainless steel thickness of not more than 20 mm.

Due to the supply of oxygen, partial burnout of the metal occurs, accompanied by the release of additional heat, which can significantly accelerate the process of melting. This method is used if it is necessary to perform a short section on any construction structure.

The separation is carried out by a graphite or steel electrode with direct current using special cutters. The electrode should be no thinner than 4-5 mm, which has a coating OMM-5, CM-7 or APSI-3. The current strength can reach 250A and allows you to cut metal up to 50 mm thick. Compressed air is supplied to the side with a pressure force of 0.4-0.5 MPa. The average oxygen consumption varies from 100 to 160 l/min.

Metal air-attachment circuit

If you use a cutter like RGD, then the electrode holder is held in the right hand, and the cutter itself in the left. As soon as the metal begins to melt, a stream of air is supplied to it and blow it.

How to make a hole in the metal welding?

The inverter apparatus is designed for metal welding. However, this is far from its only purpose. Often in the process of welding due to a large current, metal sheets are burning. Thanks to this property, the welding machine can also be used for cutting metal products, as well as creating a hole. Typically, a regular drill and drill is used for this, but if it is necessary to create a large diameter to choose suitable drills not so simple. If such a problem arises, manual arc welding will come to the rescue.

With its help, you can burn a hole of any diameter or cut even a very thick metal. But in order for the result to correspond to expectations, you must be able to use equipment for welding and know the technology of cutting metal sheets and some nuances.

Equipment, equipment, safety precautions

Safety precautions. Welding production is associated with electric voltage, in common people. current. Current is invisible, but capable of impressing a person to death.

We check the welding cables for serviceability and connect to inverter equipment. Reverse cable with a clothespin on metal to a minus connector. The cable with an electroder to the connector is inserted into the electroder.

When connecting the device to the network, we visually evaluate the current.consuming cable for serviceability. We were convinced of the serviceability of the cables, turn on the fork in the outlet and the toggle switch on the device, after installing the current controller into the smallest value. If the cooling fan has earned evenly, without cod and noise, then everything is fine.

The weight of the metal. When connecting heavy structures, observe precautions. During collapse, multi.ton products can lead to death or disability.

Equipment. Welding production is associated with high temperature. The welder must have:

• canvas mittens (kraga);
• Rob (special costume);
• mask with a light filter;
• respirator for work in closed spaces;
• rubber.

Crages are used for welding at heights when the hands rise up and the mittens in other cases.

Electrodes are selected for metal (carbon, additives) and diameter, from metal thickness and technical characteristics of the inverter.

The basics of welding inverter

For beginners, experienced welders advise the holder cable to attach to the body, press their hands with your elbow and wrap it along the forearm (from the elbow to the hand), take the holding in the hand. So the shoulder joint will pull the cable, and the hand with the brush will remain free.

The method will help to easily manipulate your hand.

The correct location of the cable on the forearm. You should not work with bare hands.

If you take the holder just in the hand without the backing of the forearm with a cable, then during the welding the hand will get tired and the cyst movements will bring the cable into dangling movements. Which will affect the quality of the welded joint.

How to cook inverter welding correctly ? Install the welding current on the device according to the diameter of the electrode, the connection type and welding position. Setting instructions are available on the device and a pack of electrodes. We take a stable rack, we take the elbow from the body (you can’t press), put on the mask and begin the process.

It is better to weld an inverter for beginners with metal blanks of more than 20 cm.

It is known that a beginner, dressing a mask and lighting an arc stops breathing, trying to boil the entire length of the workpiece in one breath. With short products, there will be a habit of cooking in one breath. Therefore, train on long blanks, learning to breathe correctly when welding.

Harvesties (plates) on the desktop can be put in a horizontal plane. vertically to yourself or horizontally, no difference.

Put the electrode clamped in the holder at first of the welding at an angle of 90 degrees (perpendicularly) and take it to the seam by 30-45 degrees. Light up the arc and start moving.

• If the welding is performed with an angle back, then a slope of 30-45 degrees goes towards the seam.
• If the connection occurs forward, then the electrode tilt from the seam.

The distance between the welded surface and the electrode is 2-3 mm, imagine that you are a pencil on a sheet of paper.

Keep in mind that when welding the burning electrode decreases-gradually approach the melting rod to the surface at a distance of 2-3 mm and hold the angle of inclination 30-45 degrees.

Watch useful videos on how to learn to cook electric welding for beginners:

Formula for calculating current strength

Also, to make it easier to calculate the current strength depending on the diameter of the selected electrode, we suggest you familiarize yourself with the next formula. Experienced welded ones calculate the current as follows: on 1 mm of the electrode they take about 30 amperes of current.

That is, if the Troika electrode is used, then we multiply the diameter by 3 and get an approximate value of 90 amperes. As you can see, everything is very simple, and this formula for calculating the welding current allows you to more subtly select its required values ​​depending on the thickness of the electrodes.

In any case, first we determine the thickness of the metal welded, then select the appropriate diameter of the electrode, and only after that we calculate the required current strength.

Electric.2nd

Metal welding of large thickness (20 mm or more), due to the inability to boil in one pass, the entire thickness of the product has its own specifics. The edges of the welded surfaces must be prepared.

For this, the edges grind at an angle. When connecting parts in the section, the letter V should turn out. Sometimes, one edge is stuck at an angle, and the second steps. A gap is left between the welded details, in the upper part should be a groove of 10-15 mm wide and more.

The width of the groove depends on the thickness of the metal. When welding metal of different thicknesses, the edge of the thicker one grows to the cross.section of the thin.

When welding VSTOK and the presence of intersecting seams, stresses occur, leading to deformation and even destruction of the product. This is especially manifested at low temperatures when the metal loses its plastic properties.

Strong fixing of parts in equipment also causes excessive stresses. Long seams with a large section lead to the same.

To weld a thick metal sheet is required so that the time between the application of the subsequent layers is minimal. In order to avoid stresses, it is necessary to lay the next seam in a hot layer. The thickness of the layers should be within 4-5 mm, this will provide sufficient heating.

When welding thick metal due to the large depth of the welding bath, the likelihood of pore formation increases. To prevent this from happening, a cascading method of welding or the “slide” method is used.

During welding, a transverse shrinkage occurs, which can reach 4 mm with a metal thickness of 40-50 mm. When welding thick sheets, it is necessary to make a 2-3 cm length with a length of every 30-50 cm.

To reduce stresses, you can perform the work of two welders at the same time. Heating of thick metal to 150-200 ⁰C also reduces internal stresses, slows down crystallization, which leads to a longer gases release and, accordingly, a decrease in the number of pores.

How to cook thin metals with an electrode

It is generally considered a sheet with a thickness of less than 2 mm. There are three options that are found during welding of thin metals:

• A sheet or thin workpiece must be connected to a thicker part. This is the easiest option. If possible, you should choose it.
• It is required to cook two thin sheets with each other. By applying sheets on each other, the process is facilitated.
• You need to connect two sheets of VSTOK. The most difficult case. The probability of a burn without work experience is very high.

There are several tricks that welders resort to when connecting thin metals.

Arc welding

Electric arc welding (EDGS) is a type of unreasonable connection of parts obtained by melting the metal with an electric arc that occurs when the voltage is supplied to the electrode from the current source. When exposed to the connected parts of such an arc, a welding bath of molten metal is formed, after cooling and solidification of which a seam connecting the parts is formed.

When welding products of large thickness (more than 20 mm) using EDGS, it is impossible to boil the entire thickness of the product. Therefore, in this case, multi.layer imposition of seams is used. Before you start welding of thick metal, you need to prepare its ends. Most often, the edges of the ends grind at some angle. Between the details leave a gap.

When performing the first root (connecting) seam, a thin electrode of 1-3 mm thick is used. Its use allows you to fix the parts and avoid a burn.

The subsequent filling of the weld is carried out by an electrode of a larger diameter. In this case, the layer should be laid according to the uninquisitive previous layer. The thickness of the layer for sufficient warming should not be more than 4-5 mm.

Classification of EDGS

With manual EDGS, the welder manually moves the electrode, as a result of which the weld is formed. With semi.automatic welding, the filler wire is supplied automatically, and the electrode is moved manually. With automatic welding, both wire and electrode move automatically.

Equipment

The most common is manual EDGS. When performing this kind of welding are used:

• welding machine;
• manual tool of the welder;
• devices to facilitate welding.

Welding apparatus is, first of all, a power source for an electric arc.

Welding transformers, rectifiers (inverters) or generators are used as power sources for EDGS.

Approximate cost of inverter current sources for Yandex.Market

The welding transformer is designed to lower the network voltage into a lower arc burning and ensuring the required current. Welding rectifiers consist of a decreasing transformer and a semiconductor rectifier. They nourish the arc with direct current. Generators provide power to electric shows by converting mechanical energy into electrical.

In addition to the power source, the welding machine includes an electrode, an electrode and wire holder connecting a power source to a welding bath. The electrode is usually a filler material with coating designed to protect the welding bath from the effects of the external atmosphere. Holders for the electrode are a screw or clamp type.

The approximate cost of electrical holders for Yandex.Market

As devices, the welder should use a protective mask that filters the UV and IR radiation of arcs, respirator and special clothes. In addition, as a hand tool, the welder is supposed to have a hammer, chisel, metal brush.

Welds

When welding thick.walled parts, pores or cracks may occur. Methods are used to prevent them in welding:

In the first case, at the beginning, at the joint section of 200-300 mm, a layer form after cleaning it from scale on it is welded a layer, which is 2 times longer than the first. Then they retreat 200-300 mm from the beginning of the layer and weld the layer thus fill the entire welding seam with a seam on both sides of the layer

When welding metal with a thickness of 20 mm, the cascade method is used. In fact, this method is a type of “slide” method. In this case, the entire seam is divided into segments of 20 cm. First, the lowest section of 20 cm is boiled. Then a second layer 40 cm long is placed on top of the first layer. The third layer 60 cm long is placed on top of the second layer. Thus, lay the layers until the seam is filled above the site after that, short seams are cooked from the site in both directions. Thanks to this, the welding zone will be heated all the time, and there are no cracks.

With the block method, the seam is first boiled in separate areas (blocks), and the gaps between them are brewed until the end of welding of the entire seam.

Application area

The ultimate goal of cutting is to obtain blanks of the desired size when separating the metal into parts. In serial production or, if necessary, cut the material of a large thickness, cutting metal with electric arc welding is used. Since the method does not have high accuracy, it is successfully used to dismantle large structures, for example, pipelines. Attracts the simplicity of this method.

The requirement for high qualification of the welder is not presented. For welding and cutting from equipment, a welding machine is required, and from the tools. Special electrode.

Technological process

Electric and metal cutting technologies begins the same. Welding apparatus is connected to the network. With one cable it is connected to the details, and the second to the holder with the electrode. The value of the current is set depending on the thickness of the material and the size of the electrode. Tapping the electrode along the metal surface, arouse the arc. Metal under the influence of high temperature begins to melt.

In contact with air oxygen, an beginner firm metal is oxidized. This can lead to defects in the form of oxides. Inert protective gas is used to avoid this. Most often, Argon and Helium act in this role. Gas that is used for cutting and welding metals is supplied to the welding bath.

• Dividing. Implies the possibility of flowing molten metal from the resulting section. The diameter of the electrode is greater than the width of the leaf. If the sheet is located in a vertical plane, then welding is made by the method from top to bottom. The electrode is located perpendicular and move along the intended line. If through holes must be made, then you should start with them.
• Superficial. It is used when it is required to lay various kinds of grooves on the surface of metal, as well as remove defects in the form of influxes. To obtain wide grooves by the electrode, transverse oscillatory movements are made. Moving is made with a slight immersion of the electrode deep into the metal.
• Cutting holes. First make a small hole, and then expand to the desired size. A slight deviation of the electrode from the perpendicular to the surface towards the circle is permissible.

Necessary tools and equipment

In the process of performing the work, you need:

• welding inverter (transformer), which produces the current of a given force necessary to create a welding arc;
• hammer for metal;
• cleaning brush;
• electric wires with connecting couplings;
• Electrodes and holders for them.

For cutting metal, it is advisable to use electrodes indicated by lake marking. They are distinguished by a special coating with certain heat resistance, which provides high performance and good quality of the strip of cut. When using them, a stable arc is formed, which creates the required amount of heat. Special Electrodes of the OPR allow you to cut direct or alternating current from any spatial position.

Welding cutting is a process of increased danger to humans. With non.compliance with safety precautions and the absence of the necessary equipment, you can get electric shock. Visible and ultraviolet rays negatively affect the eyes. Harmful substances releasing during cutting affect the functioning of the respiratory tract. There is a threat to get burns of the skin surface with hot metal. Therefore, in the process of cutting, it is necessary to provide:

• reliable protection of the metal body of the welding machine;
• the presence of exhaust ventilation in the room;
• Special protective clothing: tarpaulin robe, mittens, a protective mask with dark glasses, rubber shoes, respirator.

When cutting metal in a closed space, it is desirable that an assistant, ready to help in an extreme situation, is watching outside the actions of the employee.

Electric welding metal cutting technology

The process of cutting metal is easier than welding, since there are no special requirements for the quality of the edge. Therefore, this technology is optimal for training, mastering the principles of working with an inverter.

Before starting work, it is necessary to make sure that all the electric cables used are in good condition. The creation and retention of an arc does not cause much difficulties. It is lit as a result of tapping or stirning the electrode on a metal blank. The value of the current on the inverter is set depending on the size of the electrodes, the thickness of the material, the type of required section. There are three main varieties of cuts.

Separation cutting

The material is installed in such a way that the free flow of molten metal from the cut line is provided. With a vertical location of the sheet, the separation cutting is carried out from top to bottom. On the horizontal surface, the cut is made from the edge of the material. If a large sheet is cut, you can start the process with a hole made in the middle of the workpiece.

Surface cutting

This variety is used to lay grooves on the surface of the material, align the influx and defects. During operation, the electrode should be located with a slope of 5º-10º to the surface. With surface cutting, movement is carried out with a slight immersion in the created cavity. If you need to lay a wide groove, the electrode should be performed by transverse movements of a given size.

Cutting holes

This operation is performed by gradual expansion of a small hole to the required size. When cutting holes, the perpendicular location of the electrode allows small deviations towards the formed circle.

Features of the use of different types of electrodes

For the process of cutting metal surfaces, the use of various electrodes is possible:

Cutting with a melting electrode is accompanied by the melting of a metal by an electric arc from the exposure zone. The work is performed by steel electrodes with a diameter of 2.5 to 6 mm, which differ in greater tightness than when welding. High.quality coating (manganese ore, Potash) creates a small visor covering the arc area, which contributes to the concentrated heating of the material.

Coal electrodes are used when a certain quality and width of the resulting cut is not required. When working, the surface of the material is located with a small slope to facilitate the flow of metal. Thus, you can process blanks of cast iron, steel, non.ferrous metals. The use of an electrode 10 mm thick will be optimal.

Electric.type cutting of non.ferrous metals, alloy steel can be produced by non.melted tungsten electrodes, which are used much less often than metal or coal. In this case, cutting should be carried out in a protective gas environment.

In the absence of special electrodes intended for cutting material, ordinary welding. In this case, you should choose the right diameter: for thin metal, electrodes with a diameter of 3 mm are used, for thicker. from 4 to 6 mm.

Tubular electrodes.

The main difference between tubular electrodes, in full accordance with their name, is that the central melting element is not an integral rod, but a hollow thick.walled tube. The metal of the tube serves as a conductor for creating a heating electric arc, and oxygen is supplied along the tube channel, oxidizing metal at the site of the cut and ensuring its combustion and blowing out of the cut (rice.2). Tubular electrodes are widely used, in particular, for cutting metal in underwater conditions. They come in two types. steel and carburundium, and differ in diameter, length, and, accordingly, combustion time.

The use of tubular electrodes has its disadvantages. this is both the higher cost of the electrodes themselves, and their faster, in comparison with all.metal, the rate of combustion. In addition, oxygen supplied directly through the electrode channel creates interference for stable burning of an electric arc. In this regard, the type of electrodes for oxygen-duma cutting of metal also has spread, in which a continuous rod, and a separate channel for supplying oxygen is attached to it.

Metal cutting process using electrodes

Since the manual arc method of cutting metals using special electrodes and inverter is the most popular, we will consider the main stages of this work process:

• Preliminary preparation includes checking the serviceability of the used cables;
• The ignition of the arc is carried out by tapping or struggling the electrode on the surface of the metal;
• The current on the inverter is set based on the diameter of the electrode, the thickness of the cut metal and the type of cut: thin metal should be cut with a rod with a diameter of 3 mm.;
• for metal more thickness. 4 or 5 mm.

Important! When cutting thin metal, the current indicator should be increased (it is possible up to two times higher than usual).

Following these recommendations and correctly setting important cutting parameters, you can quickly and without problems master the technique of metal processing techniques.

Below are the brands of special electrodes for cutting and stringing metals.

Varieties

Cutting electrodes are of various types. The most often usual electrodes are used, inside which there is a metal rod, and coating on top of it. The coating is routine or basic. The result of the use of this type of electrodes is an even section in the required place of metal structure. Burning the arc is stable, the oxidation of the metal is minimized.

It is most advisable to use metal electrodes for cutting cracks, as well as for removal by cutting surface defects. Before starting work, it is necessary to hold metal electrodes at high temperature.

Metal cutting with a coal electrode has no special differences from the use of metal consumables. However, this type is more suitable for welding. The advantage of cutting by a coal electrode lies in a slower melting rate than when using metal consumables. This helps to obtain a cut with a neat appearance.

In addition, when using coal electrodes, even a slight current strength causes quick warming up the part to be cut. This leads to a decrease in electrodes consumption. It is advisable to work on direct current with reverse polarity. You can cut with an electrode a thickness of up to one hundred millimeters. Unlike other types, carbon electrodes do not melt, but gradually begin to burn out. This leads to a decrease in the production of slag, and obtaining a cleaner cut.

Tubular electrodes are used for oxygen-pushing metals cutting. Their difference is that the basis is not a metal rod, but a tube filled with oxygen. During melting, oxygen begins to gradually be released, contributing to the formation of the cut. The disadvantages include the fact that the flow of oxygen can violate the stability of the arc burning.

Tungsten electrodes. these are electrodes for plasma cutting. Cutting is carried out in a protective gas environment. The current strength should be set higher than when using this type of electrodes during welding. This will allow you to get a uniform cut throughout the thickness of the product.

Principle of operation

In order to cut metal using the inverter, you should choose the right current values. It depends on the type of cut, metal thickness and electrode selected. During the dividing cutting, the metal sheet should be installed in such a position that the molten metal is able to freely flow out.

Electrodes must be in a strictly perpendicular position in relation to the surface. If the sheet is located vertically, then the electrode movement should be carried out from top to bottom. The electrodes themselves should be thicker than the cut product. Cut thin metal with electrodes with a diameter of 3 millimeters. For thicker electrodes of 4 and 5 millimeters are used.

To eliminate surface defects, surface cutting should be used. In this case, the electrode should be kept under a slight inclination, fifth degrees five to ten. If necessary, make a groove of the electrode, it is necessary to rock from one side to the other, gradually immersing it in the formed cavity.

Electrodes can also be erupted in the metal holes. Pay holes until the desired diameter is achieved. First burn a small hole, and then gradually expand it. The electrode must be kept strictly perpendicular to the surface in which the hole erupts, otherwise the edges may turn out not entirely even. Only minor deviations from the right angle are allowed. Before starting the process, it is necessary to check the serviceability of the equipment used. The arc should be kindled with chirking or tapping.