In order to be able to carry out work related to connecting elements of metal structures at any time in a home workshop or on a personal plot, it is enough to purchase a modern welding machine and learn how to weld with a welding inverter.
Welding work has long been widespread not only in serious production, but also in everyday life.
Design and advantages of inverter welding machines
The great popularity of inverter equipment among home craftsmen is explained by the fact that with the help of such compact devices, which are also lightweight, it is possible to make high-quality, reliable and accurate welded joints, even without high qualifications.
The design of any welding inverter consists of such elements as:
- power supply with rectifier unit and filter;
- inverter unit that converts direct current into high-frequency alternating current;
- transformer for reducing the voltage of high-frequency current;
- power rectifier designed to produce direct current at the output of the device;
- an electronic unit that performs device control functions.
Innovative technologies implemented in the design of inverters make it possible to obtain high-quality welded joints without any problems. Due to their compactness, such devices do not take up much space, and due to their light weight (5–15 kg), they can be moved anywhere without much difficulty.
If you learn how to work correctly, you can use it to weld any metal structures. Each new inverter comes with instructions, from which the owner of the equipment can glean a lot of useful information: how to properly connect the device, which electrode to choose in order to weld products from a particular metal, etc.
Patterns of electrode movement depending on the type of seam (click to enlarge)
However, often an inverter device falls into the hands of a home craftsman, the instructions for which are not translated into Russian or are missing altogether. It is very important to learn correctly, because if you act at random, it will be difficult to weld metal well. In addition, you may encounter equipment failure.
However, if you follow generally accepted rules, you can work on any model of inverter and effectively solve all the tasks. After carefully studying these rules, watch the training video, which will help reinforce the theoretical material with visuals.
How to prepare equipment for operation
Before you start welding metal, prepare all the necessary equipment to ensure your safety: a welding mask, special clothing made of thick fabric, work shoes and gloves, which should also be made of thick material.
In order for the weld to be of high quality, it is necessary to select the correct electrodes. Their type and diameter are selected depending on the metal from which the parts being joined are made, the thickness of the latter, as well as the welding modes. Since the surfaces of the workpieces to be welded must be thoroughly cleaned, you also need to prepare a brush with metal wire bristles.
Before connecting the inverter to the electrical network, you need to check whether the network parameters correspond to the characteristics of the connected equipment.
These parameters include the strength of the electric current and the voltage value, which must be within the range specified in the passport for the inverter. The device should be connected to the power supply through an automatic circuit breaker, which will prevent equipment breakdown if a short circuit occurs in its electrical circuit or the voltage increases sharply for another reason.
Before starting welding, it is necessary to take care of the condition of the working site. The inverter should be installed on a flat surface, and there should be enough space around its body to ensure free movement of air, due to which the device is naturally ventilated. Do not cover the device body with fabric, which will restrict the flow of air to its ventilation grilles.
The welding process is accompanied by high temperatures and splashing of molten metal, so there should be no flammable, fire or explosive substances on the work site.
After all preparatory activities have been completed and safety requirements have been met, you can proceed to the following actions:
- connecting the power cable and ground cable to the corresponding connectors of the inverter;
- fixing the mass cable on the parts to be welded (a special clamp is used for this);
- connecting the device to the power supply and setting welding operating modes on it;
- fixing the electrode in the welding holder.
The sequence and correctness of performing such actions is well demonstrated by the training video. Now that the inverter is connected to the electrical network and the electrode in its holder is ready for use, you can begin welding.
Features of welding work using inverter devices
The first thing you need to do to start cooking with an inverter is to light an electric arc between the surface of the part and the tip of the electrode. To do this, the latter makes a scratching movement along the surface of the workpiece, as a result of which a bright flash should appear. The metal in the arc zone will begin to melt. You can learn how to light an arc correctly and do it quickly by watching a training video.
When performing welding, it is important to monitor the length of the arc, which should approximately correspond to the diameter of the electrode used (in this case, the parts will be evenly melted, which will allow the formation of a high-quality weld). It is necessary to ensure that such penetration occurs evenly throughout the entire welding process.
The quality and reliability of the weld is also influenced by the polarity of connecting the inverter power cable and the ground cable. To choose this polarity correctly, you need to know exactly what material the parts being connected are made of. Most grades of steel and other metals are best welded with direct polarity; only some alloys are combined with reverse polarity.
The design of modern welding inverters ensures smooth and efficient regulation of the operating current, which makes working with such devices simple and comfortable even for novice welders. You can judge that the welding current is selected incorrectly based on a number of factors. So, if it is too small, then the weld seam turns out to be too convex and narrow, and the parts in such cases are poorly fused. If the current is too high, then intense spattering of molten metal occurs, and burns may appear on the surface of the parts being connected.
The choice of welding current depends on the diameter of the electrode you are going to weld with. Thus, when welding metal with a thickness of one to three millimeters with electrodes with a diameter of up to 1.5 mm, the welding current strength is selected in the range of 20–60 A. In the event that larger diameter rods are used, which can be used to weld metal 4–5 mm thick, the strength welding current is selected within 100 A.
While watching a training video or watching the work of a qualified specialist, novice welders are often interested in why slag is knocked off the surface of the finished weld. This is done in order, firstly, to check the quality of the weld, and secondly, to give the finished joint an attractive appearance. A seam cleared of slag shows all the mistakes made during welding.
Of course, you should not expect that novice welders (or so-called dummies) will immediately produce beautiful and high-quality welds. Mastery, including in welding, does not come immediately after familiarizing yourself with theoretical material and watching videos; it is developed only through experience.
How to choose the right welding inverter and electrodes for it
Correctly selected electrodes play a big role in the formation of a high-quality and reliable welded joint. It is impossible to learn how to choose them from a video; to do this, you should adhere to generally accepted recommendations and the following principles.
- When working with medium and low carbon steels, carbon electrodes are used.
- Alloy steels are welded using electrodes produced in accordance with GOST 10052-75 and 9466-75.
- For welding cast iron products, OZCh-2 grade products are used.
Thin steel is used to make a wide variety of structures. At enterprises, welding work is carried out using special machines that provide products with optimal connections. How to weld thin metal with an electrode at home? What equipment works best? These are the questions asked by inexperienced welders forced to work from home. You will find information on how to properly weld thin metal with an electrode in this article.
What are the difficulties?
The importance of the question of which electrodes are best for welding thin metal is due to the fact that if they are chosen incorrectly or the work rules are not followed, the master may have problems. These include the following:
- Due to the fact that you have to work with fairly thin material, it is important to correctly calculate the current strength. Otherwise, several through holes may form in the metal. They are also a consequence of slow stitching.
- In an effort to prevent burns, many welders are in too much of a hurry when going through a joint. As a result, an uncooked area remains on the treated surface. Experts call such areas lack of penetration. As a result, the connection is obtained with poor tightness, and the product is considered unsuitable for working with liquids. In addition, the metal has a low tensile and fracture resistance.
- Often, those who do not know how to weld thin metal with an electrode make another mistake, namely, they leave sagging on the back of the products being joined. If the surface looks normal from the front side, then from the back it leaves much to be desired. This can be prevented using special substrates. It is also advisable to reduce the current or change the welding technique.
- It happens that the structure becomes deformed. The reason is overheating of the sheet steel. Since the metal structure remains cold at the very edges, and the intermolecular component expands at the welding point, waves begin to form on the surface of the steel, which leads to overall bending. According to experienced welders, the problem is solved by cold straightening - the sheet is straightened using rubber hammers. If this is not possible, then you will have to correctly alternate the sutures during welding.
To prevent these shortcomings, you need to know how to weld thin metal with an electrode.
About current sources
For welding, such sources can be transformers and inverters. According to experts, the first option is now considered outdated and will soon be abandoned. Despite the presence of undeniable advantages (high reliability and endurance), transformers drain the electrical network too much, which often leads to damage to wiring and electrical equipment. Inverters, on the contrary, do not drain the network and, according to experts, will be an ideal option for a novice welder. If previously, when working with a transformer source, the electrode would stick to the surface and burn the network, then with an inverter source the welding current simply turns off. At the very beginning of the arc ignition, a current surge is observed on the transformer, which is undesirable. The situation is different with inverters - in these devices, thanks to the presence of special storage capacitors, the energy pumped earlier is used.
About arc welding
According to experienced craftsmen, the success of arc welding depends on the quality of calcination of consumables. The optimal temperature is considered to be 170 degrees. In this thermal regime, uniform melting of the coating occurs. At the same time, it is convenient to manipulate the arc, forming a seam. Welding electrodes must have a high-quality coating. In accordance with the technology, an intermittent arc is formed by short-term separation of the electrodes from the weld pools. If the product has a refractory coating, then a kind of “visor” will certainly form at its end, which will interfere with contact and the creation of an arc.
About the cross section of electrodes
According to experts, the power of the output current directly depends on the diameter of the electrode. For a thick one, you will need a source that can provide a large amount of current. Thus, for a certain diameter, a specific power indicator is provided, beyond which it is impossible to go.
If it is deliberately lowered, then the weld simply does not form. Instead, only metal veins with slag and electrode coating will remain on the surface being treated. For example, if you work with a 2.5 mm electrode, the minimum current should be 80 amperes. It is increased to 110 amperes when working with an electrode 3 mm thick. Judging by numerous reviews, the idea of performing welding work with electrodes with a cross section of 3 mm at a current of 70 amperes is initially a failure, since no seam will be produced.
Where should I start?
Before welding thin metal with an electrode, you need to choose it correctly. Due to the fact that you will have to cook with a reduced voltage, it is not advisable to use 4-5 mm electrodes. Otherwise, the electric arc will “stall” and combustion will not occur fully. What electrodes should be used to weld thin metal with an inverter? Judging by numerous reviews, the best option would be electrodes with a thickness of 2-3 mm.
Anyone who does not know how to weld thin metal with a 2 mm electrode should use a special calculation table. For material whose thickness does not exceed 1 mm, a current of 10 A and 1 mm electrodes are used. Judging by numerous reviews, they burn out quite quickly. If you have to work with 1 mm metal, the current should vary from 25 to 35 A. For such welding you will need electrodes with a cross section of 1.6 mm. 2 mm are recommended for sheets with a thickness of 1.5 mm. The current indicator in this case is higher and amounts to 45-55 A. For metal 2 mm thick, electrodes with a cross section of 2 mm are provided. A current of 65 A is used. How to weld thin metal with a 3 mm electrode? As experts recommend, a product with this cross-section can be used to work with metal 2.5 mm thick at a current of 75 A.
About butt connection
Due to the fact that thin steel sheets are joined into a joint, the material is often burned through. To prevent this, you need to properly align the edges of the plates. Most welders prefer to overlap the plates. In this way, a base will be formed for the deposited metal, preventing its burning. Nevertheless, many beginners are interested in how to weld thin metal with a 3 mm electrode into a joint? As experienced welders recommend, when placing plates, it is not necessary to cut their edges. There is also no need for a gap between them. It is enough just to bring the ends of the sheets to be welded closer to each other and tack them. It will be easier to work in low current mode and using relatively thin electrodes.
About butt welding methods
Butt welding is carried out in several ways:
- First, the unit is set to low mode. The seam is formed quickly and clearly along the joint line. There is no need to perform oscillatory movements.
- This method uses a slightly increased amperage. To form a seam, it is recommended to use an intermittent arc. This measure is determined to give the material time to cool before a new “portion” of additive is applied to it.
- The third method is practically no different from the previous one. However, in this case, welders use special substrates, the task of which is to maintain the heated area and prevent it from collapsing. Judging by the reviews, it is undesirable to use a metal table as such a substrate. Otherwise, it will simply weld to the product itself. The best option would be a graphite lining.
- Some craftsmen practice a checkerboard pattern of weld seams. This method prevents deformation of the structure. You can also place seams in small sections. To do this, a new seam begins to be formed from the point where the previous one ends. This method ensures uniform heating of the product, preventing its deformation.
Progress
Before welding, the parts to be joined are thoroughly cleaned of rust. Units that provide direct current are good because reverse polarity can be used for welding.
It is enough to insert the electrode into the holder, which is connected to the cable marked “+”, and the cable with “-” to the surface of the steel part. This connection method will provide greater heating to the electrode, and the metal surface will warm up less. If the master pursues the goal of heating the joined products less, then they need to be placed vertically. According to experts, it is important that they are tilted within 30-40 degrees. Cooking is carried out from top to bottom. The tip of the electrode should be moved in one direction without any deviation to the sides.
About welding galvanized steel
This material is also called galvanizing. It consists of thin sheets of steel coated with zinc. Before joining the edges, the coating in this area of galvanization is completely removed. This can be done mechanically using an abrasive wheel, sandpaper or a metal brush.
The coating is burned off quite well with a welding machine. Due to the fact that zinc, evaporating at a temperature of 900 degrees, emits very toxic fumes, this work must be performed in the fresh air or in well-ventilated areas. After each pass with the electrode, you need to knock off the flux. When the zinc is completely removed from the surface, you can proceed directly to welding. Galvanized pipes are mainly connected in two passes using electrodes of different brands. For the first pass, products containing rutile coating are used. Electrodes OZS-4, ANO-4 and MR-3 have proven themselves well. During welding, they should oscillate with a small amplitude. To form the upper facing seam, experts recommend using DSK-50 or UONI 13/55 electrodes. The area of the last seam should be slightly wider.
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
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.
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.
Good general material can save a novice welder a lot of time and help him do without special courses. Learning to weld correctly is not difficult; it requires knowledge of theory and a certain amount of practice.
Without knowledge of theory, it is impossible to master welding, because:
- You won't get a quality seam.
- You may be injured or others may be injured.
- The equipment may be damaged.
Electric welding is the joining of metal parts by fusion with an electric arc. An electric current passed through the gap between the electrode and the metal causes enormous temperature, melts the edges, and transfers the metal from the electrode to the seam. It turns out that two metal surfaces are connected monolithically.
Electric welding is popular. The device is small in size and is capable of hermetically connecting parts in any spatial position; welding is fast and controllable. When working, be aware of the health risks:
- Eye injury. The welding arc emits light energy, which can burn the cornea of the eye and be imprinted on the retina. A feeling of sand under the eyelids, difficulty blinking, swelling - these symptoms go away for quite a long time. A mask with special glass will help protect your eyes; before lighting the arc, warn others by shouting: “Eyes!”
- Electric shock. Electric arc is the passage of electric current through the gap between the electrode and the metal. The greater the current, the brighter the arc. But if this current passes through a person's body, he will die. To avoid electric shock:
- Monitor the integrity of the cable braid and the insulation of the holder.
- Use high-quality insulated holders; do not grab the bare parts of the holders with your bare hands.
- When working continuously, wear safety shoes with rubberized soles.
- Skin burns. The ultraviolet radiation of the arc and scale flying in all directions injure the skin. To avoid problems, use protective gloves - gaiter. You should dress only in cotton or specially impregnated clothing - welding overalls, jeans. Cotton gloves or welding gloves are used to protect hands. There should be no exposed skin when welding.
- Gas poisoning. All work must be carried out in a ventilated area, under a hood or in the fresh air. It will be useful to use filtering half masks or respirators.
Types of electric welding
There are several main directions:
- MMA. Welding with an electrode in a protective coating. A universal technology that allows you to get an excellent seam in any spatial position. Simple devices for converting alternating current into direct current, transformer or inverter type, are used. The current strength depends on the thickness of the metal being fused and the electrode used, ranging from 30 to 200 Amperes. An electrode is a metal rod coated with coating. During welding, the coating melts and protects the melt from air.
- MIG. Welding in a shielding gas environment. The electrode is a wire fed into the weld pool at a constant speed. Carbon dioxide or a mixture of gases is supplied to the welding zone through a hose. They displace oxygen and protect the weld seam. The advantages of this type of welding are the absence of slag, high quality of the weld, and the ability to weld thin metal.
- TIG. Welding of non-ferrous metals in a protective gas environment using a non-consumable electrode. Widely used for joining non-ferrous metals and alloys.
There are several types of different technologies used in automotive or shipbuilding. They require special qualifications of the welder. The skills of fusing or manually feeding wire into the weld pool are specific and accessible to welders of the highest ranks.
Welding technology
Welding - joining metal parts by melting the edges and adding filler metal. As a result, a weld seam is formed, the edges are firmly connected.
Signs of a quality seam:
- Penetration. The weld metal must penetrate the entire thickness. During the welding process, the edges melt evenly; if you melt one side, the bead will turn out uneven.
- Uniformity. The joint must consist of solid metal, without inclusion of slag or shells. Skips and failures are not allowed.
- Strength. After the seam cools, microcracks may form.
- No undercuts. An arc that is too strong “cuts” the edges of the parts, weakening them.
- Convex uniform shape. Both an excessively thick roller and a concave roller are considered defective. This indicates an incorrectly selected current strength.
The seam should be uniform, without unnecessary “scales”, sagging, or bends. The width of the seam is determined from the thickness of the parts being welded. Too narrow will be fragile, too wide will weaken the product.
Before connecting the parts you need:
- Determine the type of connection - butt, overlap, corner, T-joint.
- Determine the spatial position - vertical, horizontal, ceiling.
- Assess the thickness of the parts to be welded.
- Select electrode. The thickness depends on the depth of the seam.
- Determine the current strength. The packs contain approximate recommended tables, but you should rely on your personal feelings. It is better to choose the maximum possible current strength, but do not burn through the metal. The current strength on ceiling connections is lower than on horizontal ones.
- We prepare the parts - we chamfer the thick parts and use tacks to set the gap. We clean parts from rust and paint.
Learning to cook with electric welding
Having prepared the parts for welding, set the approximate current strength and put on special clothing, you can prepare for the actual welding.
We connect the device.
- We connect the wires to the welding machine. Usually they use a “reverse” connection - the minus (mass) is connected to the surface to be welded, the plus to the holder. Direct connection is used as recommended by electrode manufacturers.
- Checking the holder. It can be homemade or factory-made. The main requirements are the strength of the electrode fixation, the possibility of quick replacement, the absence of live parts, and the heat insulation of the handle. Poor contact between the holder and the cable causes increased resistance and heating, and the insulation burns out.
- Connect the ground. The simplest way is to weld it to metal, but it is better to use clamping pliers or magnetic mass.
- Depending on the spatial position, it is important to choose the angle of connection of the electrode to the holder. Typically, the electrode should be pointed at a 45 degree angle to the part being welded. The depth of penetration and the height of the weld bead depend on the inclination of the electrode.
Choosing electrodes
There is a technology for self-production: the wire is dipped into liquid glass and rolled in sand with the addition of additives - borax, soda, salts. Today there are various types of electrodes on sale.
The electrodes are separated:
- With basic coating. They are difficult to ignite, but produce little slag. They are easy to control and the seam quality is high. Requires good welder training.
- With rutile or acid coating. They give more slag and require skills. Easy to set on fire, the seam is better protected. The advantage of this coating is that there is less formation of gases during welding, which is good for health. It is better to use this type when studying.
The diameter is selected based on the thickness of the parts being welded. The thicker the seam, the higher the current, the thicker the electrode. It is optimal to use, for example, an electrode with a diameter of 3 millimeters for welding metal with a thickness of 2 - 4 mm.
Lighting the arc
Beginner welders face difficulty in the beginning. There are several ways to light an arc correctly:
- Scratching. A simple method, the movement resembles lighting a match. The resulting arc is held and transferred to the beginning of the seam. The disadvantage of this method is the sagging and splashing of metal outside the arc.
- Hit. A film of slag forms at the tip of the electrode, and the arc cannot flare up. To knock down the slag, you need to lightly tap the surface several times. The resulting arc spark is retained and transferred to the beginning of the seam. With this method, the electrode often “sticks” - it becomes welded. It is useless to tear it off; you need to “break it out” with rocking movements.
The ignited arc forms a weld pool. When starting welding, we make a small circular movement - stir the bath.
To ensure that no traces of arc ignition are left on the part, we use the following life hacks:
- We scratch along the seam, light an arc and transfer it to the beginning of the seam. The movements do not extend beyond the seam, and traces of arc ignition are welded.
- We use the starting plate. You can ignite the electrode and start welding on a piece of metal docked to the beginning of the seam. Afterwards the starting plate is broken off or cut off.
Selecting the current strength
To obtain a controlled weld pool, you need to correctly determine the current strength. It depends on:
- The ratio of the diameter of the electrode to the thickness of the metal being welded.
- Spatial position.
- Welder movement speeds.
Before starting work, the training seam is welded. The correct current strength is determined by the nature of the bath.
Experienced welders set the maximum values - this helps to weld faster.
Horizontal seams are welded at high current, on vertical seams the current is reduced by 10 - 15%, ceiling seams require a reduction of 20 - 30% relative to horizontal ones.
Hold the electrode correctly
The quality of the seam is greatly influenced by the length of the arc, the trajectory of movement, the welding speed and the angle of the electrode.
Electrode movements
- Reciprocating movements along the seam. They produce a narrow seam with good heating. Can be used when connecting thin parts with a small gap.
- Transverse vibrational. Each welder has his own “signature” preferences and habits - some lead with a crescent, some with a “figure eight”, Z-shaped, multi-turn oscillation. It is used if you need to get a wide seam, with a large gap or welding chamfers. The rule is that the thicker the part, the longer you need to linger on its edges to warm it up well.
Arc length
A common mistake made by novice welders is failure to maintain the arc length. A “short” arc will not heat the metal; the weld may turn out porous and uneven. A “long arc” will overheat the metal, but will spatter the metal on the surface. The joint will not work; it will be tortuous, uncontrollable, with slag interspersed and splashes around the seam. It is optimal to keep the arc length 2-3 mm.
Welding speed
If you cook too slowly, there is a risk of the metal overheating and burning. The seam will be semicircular and convex.
Rapid movement of the electrode will result in a lack of penetration, an intermittent seam. The seam will be narrow, with slag inclusions and cavities.
Electrode position
If held perpendicularly, there will be excessive heating of the part, which can lead to burnout.
A small angle of inclination will lead to the formation of cavities, making it more difficult to control the seam.
It is best to hold it at an angle of 45 degrees.
The electrode should not “push” the seam, but “drag” it. This ensures optimal heating, uniformity of the seam, and controllability of the weld pool.
Cooking correctly
Welding metal has many features and difficulties. The main thing when making a seam is not to burn through the metal, but to melt the edges.
Thin metal, the root of the seam of parts with a gap can be welded using the “tear-off” method. The arc is ignited and a weld pool is formed. The electrode rises sharply, the arc goes out, the bath begins to cool and the arc at the end of it lights up again.
Welding of thick metal and surfacing of the weld body is carried out without separation. The arc is ignited and the weld pool is gradually drawn along the seam. If necessary, oscillatory movements are performed.
If the electrode runs out, clean the slag. At the end of the bath, a depression is formed - a crater. A new arc is stirred into the crater of the previous one, and welding continues.
Defecting the seam
After welding, the seam must be cleaned of slag. If the welding is done well, the slag is separated with one blow, easily. A bad seam takes a long time to clean, the slag sticks well to the pores.
What defects you need to pay attention to:
- Edge fusion. Both edges should be evenly fused.
- Undercuts. The edges of parts melt at high current levels, creating depressions. This weakens the metal.
- Shells and slag inclusions.
- Height and width of the roller.
- Scaly roller.
Conclusion
To learn how to weld metal well, you need to know the theory and practice a lot. It’s good if there is a person who can point out to a novice welder the shortcomings and ways to eliminate them. This will form the right habits in the welder, and the seams will always be smooth and of high quality. An important factor is the welder’s attitude to his work, the desire to get a better quality weld, and the desire to admire the “little sun” at the tip of the electrode.
In order to become a specialized master, special training is required. The welding profession is taught for 3 years in vocational schools. But you can master a simple welding machine for use at home much faster. It all depends on the tasks assigned and perseverance in solving them. Practical skills are acquired with experience, and theoretical knowledge is designed to help the novice master in this. Below we will figure out how to weld correctly, what methods are available and what safety rules must be followed.
Welding technology
Today the following types of electric arc welding are known:
- Semi-automatic arc welding.
Diagram of a semi-automatic electric arc welding device
The role of the electrode is performed by a metal wire to which an electric current is supplied. As it melts, automatic feeding occurs (so that the length of the arc remains constant). At the same time, a protective gas - carbon dioxide or argon - is pumped to the welding site. As a result, the quality of the weld seam is significantly improved.
Diagram of a welding device with a non-consumable electrode
The tungsten (or graphite) rod used as an electrode does not melt, but maintains an electric arc. The deposited metal is supplied in the form of wire or rod. This type of welding can work without filler material, in soldering iron mode.
Industrial submerged arc welding plant
The electrode that creates the electric arc is fed into the layer of flux that coats the part. This creates conditions for an ideal connection of metals that is not subject to the destructive influence of air.
At home, these types of welding are practically not used. Therefore, let’s move on to consider the fourth type of welding work - manual electric arc welding.
Manual arc welding is based on the use of a special electrode in a coating
Electric welding machines for manual welding are divided into two types - alternating current and direct current. The use of alternating current allows the design of devices with high performance and power. The advantage of direct current, due to the lack of polarity reversal, is a smoother weld with less metal spatter.
In 1802 V.V. Petrov discovered the phenomenon of galvanic voltaic arc.
A device for welding metals using “electrohephaestus” was patented in 1882 by N.N. Benardos.
Russian engineer N.G. Slavyanov first used an electrode for welding in 1888.
In 1932, Soviet physicist K.K. Khrenov. Successful welding of metals under water was carried out.
Subsea pipeline repair
The operation of the welding machine is based on the creation of an electric arc at the point of contact of two metal parts. High temperature (up to 7000 o C) melts the material to a liquid state and diffusion occurs - mixing at the molecular level.
The fundamental difference between welding and gluing is the absence of auxiliary materials - the parts being joined are transformed into a monolithic structure.
Therefore, it is necessary to clearly understand that for the correct application of welding, only homogeneous metals can be used. You cannot weld aluminum to iron or copper to stainless steel. The melting point of different materials is different, and the creation of alloys is not within the capabilities of welding equipment.
There are various welding machines for welding iron structures.
- Transformers. Serve to convert mains current with a voltage of 220 V into a current with the parameters necessary to create a high-temperature electric arc. This happens by lowering the voltage (no more than 70 V) and increasing the current (up to thousands of amperes). Today, such devices are gradually becoming a thing of the past, since they are too bulky for household use and consume a large amount of electricity. In addition, the operation of the transformer is not stable and negatively affects the condition of the network as a whole - when turned on, voltage drops are created and sensitive household appliances suffer. There are one and three phase.
AC transformer for welding work
- Rectifiers.
AC to DC rectifier for welding work
Converts the alternating current of the consumer network into direct current. The operating principle of such devices is based on the use of rectifying silicon diodes, which are also called valves. A characteristic difference between a DC welding machine and an AC welding machine is the strong heating of the electrode at the positive pole. This makes it possible to control the welding process: to carry out “gentle welding”, by manipulating the settings to significantly save electrodes when cutting metal.
- Inverters.
Inverter welding machine
For quite a long time (until 2000) they were not available for widespread use in everyday life due to their high cost. But later they gained great popularity. The principle of operation of the inverter is to convert the mains alternating current into direct current, and then again into alternating, but high-frequency current. The difference between this scheme and transformer welding is that the arc obtained from the converted direct current is more stable.
The main advantage of inverter welding is the improvement of the dynamics of the electric arc, as well as a noticeable reduction in the weight and dimensions of the installation (compared to direct transformers). In addition, it became possible to smoothly regulate the output current, which significantly increased the efficiency of the unit and ensured ease of ignition of the arc during operation.
But there are also disadvantages:
- temporary limitations in use due to heating of the electronic conversion circuit;
- creation of electromagnetic “noise”, high-frequency interference;
- negative influence of air humidity, which leads to the formation of condensation inside the device.
What is needed for work
Before you start welding, you need a welding machine and equipment:
- Welding electrodes. They are selected based on the upcoming tasks. The optimal size for a novice welder is considered to be an electrode with a thickness of 3.2 mm. Thinner electrodes are used for welding miniature parts. When the electrode diameter is more than 3.5 mm. High power equipment is required.
The diameter of the electrode is selected in accordance with the planned work
- Welder suit. It includes clothing made of thick, non-flammable material and thick leather shoes. Good quality outerwear features a high collar and a double layer of fabric at the wrists. The trouser legs are wide, completely covering the shoes from sparks. The suit must include canvas gloves impregnated with an antipyrite compound (GOST 12.4.250–2013 SSBT). There are several classes of welding suits, depending on the degree of contact with aggressive environments.
The welding suit is designed to protect the welder from burns
- Mask with light-filtering glasses. It is better not to use glasses, since not only the eyes, but also the skin of the face, hair, and respiratory organs need protection. Working without a mask leads to ophthalmia (inflammation of the cornea of the eye) and retinal burns, leading to complete loss of vision. When carrying out ceiling welding work, in addition to the mask, an additional cape is put on the head and shoulders to protect against burns.
Designed to protect eyes, face, neck and respiratory organs from harmful effects
- Metalworking tools - hammer, wire brush, clamps, vice, files, etc. Ideally, work is carried out on a workbench or a special welding table. If such conditions do not exist, it is necessary to choose a place with the most stable position.
The place where welding work is carried out is cleared of flammable materials and equipped with fire extinguishing means - water, sand, technical soda. If this is an enclosed space, it is necessary to arrange supply and exhaust ventilation.
Necessary fire-fighting equipment at any site
How to cook by welding
To successfully master the technique of permanently joining metal parts, you need to master 4 basic skills, without which not a single “welding session” is complete.
Setting up the device
The basis for setting up a welding machine is the correct selection of current and voltage output to the terminals. Despite the simplicity of the formulation, the topic of customization deserves a separate discussion. But if we briefly formulate the setting criteria, we can distinguish 5 main parameters:
- Electrode structure and diameter.
The choice of electrode diameter depends on the thickness of the workpiece metal
The electrode is selected based on which group the base metal (the one to which welding is applied) belongs. Steel is classified into three groups - regular, hardened and heat-resistant. For ordinary steel, the selection criterion is the strength ratio: the strength indicator of the base metal should be close to the strength of the electrode, expressed in megapascals (MPa). The electrode coating is designed to maximally protect the joint from exposure to oxygen and nitrogen from atmospheric air. There are 4 types of coating - acidic, rutile, cellulose and basic. Each type performs its own tasks. For heat-resistant and hardening steels, the electrode is selected according to its chemical composition - the weld must have the chemical structure as close as possible to the base material. The strength of the electrode in this case is not taken into account. To select the diameter of the electrode, the best guide is the thickness of the workpiece. The thicker the part to be welded, the larger the electrode diameter will be required.
Electrodes vary in structure, diameter and purpose
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The marking reflects the structure of the rod and the chemical composition of its coating. For each type of metal, optimal conditions have been developed to facilitate the joining of parts. In addition to the properties of the materials, the marking contains information about the conditions in which the electrode can be used - open, closed construction site, high-rise or underground work, etc.
The variety of electrodes is determined by their purpose for working with a certain type of metal.
- Spatial position of the weld.
Setting the welding mode is closely related to the welding conditions. In various situations, using adjustments, you can change the intensity of the electric arc, which allows you to speed up or slow down the procedure for applying a connecting seam, and changes the cooking temperature. For example, when the welding direction is in a “top-down” position, the layer of molten metal thickens, but the depth of the seam decreases and spreads in breadth. If the welding direction is “bottom-up”, the amount of molten metal decreases, as it flows down under its own weight. As a result, the seam becomes narrower.
Types of welding work in different locations
- Number of seams.
Often the product is scalded with several seams. The first seam can be a tack weld, the next one can be the main one, and after that there is another one - securing or leveling. At each stage, the trajectory of the seam and the depth of heating of the metal can change. Using this technology, an experienced welder forms the ideal connection of parts.
Three-layer pipe connection seam
- Electrode polarity.
It is known that the temperature of the electric arc depends on the position of the “plus” and “minus”. At “plus” the temperature is always higher. Knowing this allows the user to determine the correct polarity placement. More often, the “plus” is fixed on the main part, and the “minus” on the electrode (straight polarity). If it is the other way around, the polarity is called “reverse”.
In order to accurately select the current value, the easiest way is to use ready-made tables.
But due to the fact that each device has its own design features and technological nuances, the final word still remains with the “scientific poking method” - the empirical selection of the required current experimentally.
Setting the welding current depending on the electrode diameter
Table of relationship between electrode and welding current
Current selection mode for welding standard butt joints:
A one-sided seam connects the surface of parts on one side, a double-sided seam connects the surface of parts on two opposite sides.
Examples of welding parts using various seams
You can also use a universal table for a wide range:
A simple rule is easy for a novice welder to remember. If the current exceeds the required value, the electrode will burn through the workpiece. If the current is lower than necessary, the part is not welded, the deposited metal falls off when exposed to mechanical means.
Electrode connection
The electrode can be connected to the positive or negative current output. If “+” is connected to the part, then the polarity is called straight. If “-” - reverse. Accordingly, with direct polarity there is a “minus” on the electrode, and with reverse polarity there is a “plus”. The difference between these positions is that more heat is always generated at the “positive” terminal. Experienced welders use this phenomenon to solve specific problems. For example, by manipulating the polarity, you can cook thin sheet stainless steel that is sensitive to overheating. To do this, “plus” is applied to the electrode, and “minus” is applied to a sheet of thin metal.
One of the electrode connection options
Video: direct and reverse polarity when operating an inverter welding machine
Creating an Arc
The welding process begins with the ignition of an electric arc. In all types of manual welding, the arc is created by briefly touching the electrode to the part. In this case, the end of the electrode is sharply heated to a temperature sufficient to establish an arc discharge.
The process of igniting an electrode arc requires certain skills
After a short circuit, if the arc ignites, it is necessary to maintain a distance between the end of the electrode and the part of 3–5 mm. In this case, it is necessary to take into account the fact that the length of the electrode decreases as welding progresses. When exceeding a distance of 5 mm. the arc is interrupted when the decrease is less than 3 mm. the electrode may stick to the workpiece or cause large splashes of molten metal.
Electrode movement
To create a good seam, various arc patterns have been developed along the welded area. In this case, it is considered important not only to melt the edges of the parts being welded, but also to fill the weld pool with the required amount of metal deposited from the electrode.
Various options for the trajectory of the electrode end
This can be achieved by maintaining a constant length of the electric arc and systematically moving the end of the electrode along a certain trajectory.
When producing a seam without transverse movements, the width of the joint is usually equal to b = (0.8–1.5)xd el. Where b is the width of the weld joint, and d is the diameter of the electrode.
The passage with such a seam is considered preliminary; the normal seam configuration is considered to be b = (3–5)xdel.
Therefore, the welder’s task is to pass the seam using one of the welding technologies. Different electrode end trajectories are used in different situations.
Formation of the weld structure
The melting space of electric arc welding is called the so-called. a weld pool (or crater) that occurs under the influence of heat emanating from the arc.
The weld pool is the liquid state of the weld before it solidifies as the metal being welded.
Solntsev Yu.P.
Dictionary of metallurgical terms
As the heat source moves, the melting space also moves. Conventionally, the melting space is divided into two parts. Head part (front) and tail part (rear). In the front part, the metals melt and the main and additional materials are mixed into a single whole (diffusion). In the rear, as it cools, crystallization of the dense surface of the weld occurs.
Schematic illustration of a welding crater
The formation of a seam can occur during submerged arc welding, surrounded by a shell of slag and then the arc is practically invisible. And welding is called closed.
Open welding is the process of forming a melting space surrounded by transparent gases released by the electrode coating.
Video: 10 mistakes of a novice welder
Video: how to learn how to weld beautiful seams using electric welding
Welding safety
Neglect of personal safety rules entails the most unpleasant, and sometimes tragic, consequences. Basic safety rules state:
- When using welding equipment, it is necessary to ensure reliable insulation of the wires that supply power to the device and the electric arc itself. The requirements of the equipment manufacturer regarding grounding of the unit housing, equipment cabinet, etc. must be strictly followed.
- Work must be carried out in full protective clothing, shoes and fire-resistant gloves. In rooms where welding is carried out, rubber mats and galoshes should be used. The space should be well lit.
- Welding equipment, in particular the electrode holder, must meet the standards of reliable insulation, excluding direct contact with the welder’s skin. An electrode holder is considered to be of high quality if it can withstand 8,000 or more electrode clamps.
- To ensure safety, the use of circuit breakers is recommended.
These are some of the provisions of GOST, which regulates the work of a welder. Of course, at home no one will control the implementation of the above provisions. However, it is necessary to know them and remember that they were written not for the sake of a catchphrase, but from the bitter experience of the victims.
Welding work is in second place in terms of danger after mining work. Even in households where welding is used from time to time, we must not forget about the potential dangers when working with electric current and molten metal. To maintain safety, you should only use a factory-made protective mask, special non-flammable clothing, shoes and gloves. There must always be fire extinguishing equipment at the work site - water, sand and a fire extinguisher. Don't put yourself and your home in danger by neglecting simple safety rules. It is advisable to stock the first aid kit with anti-burn medications.
