How to make electrodes for welding with your own hands. Making a welding electrode How to make welding electrodes yourself
Now you will learn how welding electrodes are made. The components (except aluminum powder) included in the coating are sorted, dried, crushed, ground and sifted through a sieve with a number of holes of at least 1200 holes/cm2. After sifting, ferrosilicon is passivated to create a thin oxide film that protects silicon from exposure to alkali. Passivation is carried out by heating to a temperature of 700 - 800 degrees and holding at this temperature for 2 - 3 hours with periodic stirring. In the absence of a protective oxide film, silicon, interacting with the alkali of liquid glass, releases hydrogen, which causes swelling of the coating and forms gas bubbles in the coating. The interaction of liquid glass alkali with silicon occurs according to the following reaction: Si + 2NaO + H20 Na2Si03 -f H2 or Si -f- 2NaO -> Si02 2H2.
After calcination, ferrosilicon is passivated a second time with water for 3–5 days with periodic stirring. Ferrosilicon, dried after passivation with water, is sieved a second time. Pre-prepared components are weighed in quantities corresponding to the composition of the electrode coating and thoroughly mixed in special mixers or manually. Glass with a density of 1.3 - 1.5 is poured into a well-mixed dry mixture in an amount of 55 - 60% of the weight of the dry mixture. Dry components with liquid glass are thoroughly mixed in a mixer or manually. The prepared creamy mass is passed through a paint grinder or a sieve with 140 - 250 holes/cm2 to obtain complete uniformity of the coating.
The electrode rods are coated by dipping them once or twice into the resulting mass. The thickness of the coating layer on the electrode rod depends on the speed at which the electrode is removed from the coating mass and the consistency of the coating. The sooner the electrode is removed, the thicker the coating layer; if the electrode is removed too slowly, the layer becomes thin.
The coating is applied to one or simultaneously to several electrode rods, the latter are fixed in special frame holders. During the process of coating the electrodes, it is necessary to periodically stir the coating mass to avoid settling of heavier components to the bottom. Electrode rods with coating applied to them are installed in a vertical position in racks or pyramids to dry in air at a temperature of 20 - 30 degrees for 3 - 4 hours. After preliminary drying, the electrodes are calcined in electric oven at a temperature of 250 - 300 degrees for 1.5 - 2 hours. The temperature in the calcination furnace should be raised and cooled gradually to prevent cracking of the coatings. Finished electrodes are accepted based on external inspection, technological testing, and the results of mechanical tests of the deposited metal.
During an external inspection of the finished electrodes, no defects (cracks, fistulas and broken areas) affecting the quality of welding should be detected on the coating surface. The coating must be applied in an even layer along the entire length of the rod and must adhere sufficiently firmly to it. One end of the electrode should be free of coating for a length of approximately 30 mm; with this end the electrode is clamped into the electrode holder.
It is desirable that the wire be close in composition to the metal being welded. Otherwise, there is a high risk that the seam will turn out to be short-lived and of poor quality. Otherwise it will immediately fall apart.
Today, 56 grades of electrode wire are produced. They all have different chemical composition. They can be divided into three main groups.
The first group is carbon wire. It contains up to 0.12 carbon. This wire is used to weld low and medium carbon steel.
The second group is wire for low-alloy steel. It contains nickel, chromium, molybdenum, titanium, manganese and others chemical elements. Well, the third group includes high-alloy wire.
Special tables can help you choose the right type of wire. According to the contents symbols it is easy to calculate the appropriate chemical composition of the wire.
Electrode wire is available in diameters from 0.3 to 12 millimeters. Most often used with a diameter of three to six millimeters. The wire must always be clean.
Electrode coating
The electrode coating is a mixture various components applied and secured to the electrode rod.
The inventor of the coated electrode is the Swedish engineer Oskar Kjellberg. He came up with the idea of coating the wire with silicate powder.
In 1908, German Imperial Patent No. was issued to Kjellberg. 231733 "Electrode and procedure for electrical soldering." The patent states that the purpose of the coating is to “protect the molten metal from oxygen and nitrogen in the air, ensure the proper physical and chemical condition of the weld, and enable welding in all spatial positions.”
Today, two types of electrode coatings are most often used: thin or stabilizing, and thick or high-quality. The stabilizing coating ionizes the arc gap, thereby facilitating the process arc welding.
It weakly protects the molten metal from the harmful effects of air. But it still gives a relatively acceptable quality of the weld, although inferior to the base metal. The simplest stabilizing coating is chalk diluted in liquid glass (sodium silicate).
A high-quality coating regulates metallurgical processes during welding and improves the properties of the deposited metal. The composition of a high-quality coating is very complex. It contains slag-forming, gas-forming, deoxidizing, alloying and stabilizing components, steel powders.
Nowadays, the most common electrodes in our country are those with calcium fluoride or, with similar properties, rutile coating. When melting, such electrodes produce flux, which protects the weld from the harmful effects of the atmosphere.
In Western countries, cellulose-coated electrodes have also become widespread. The metal rod is wrapped in plain paper, which is soaked in liquid glass and then dried. Such electrodes emit a lot of gases that protect the metal and the weld pool.
Many people ask whether it is possible to make an electrode for welding ferrous metals with your own hands at home?
The answer is no. You cannot make a normal welding electrode yourself. Because this is a fairly knowledge-intensive process, and the components included in the coating cannot always be purchased at the nearest store.
What does the great and terrible Internet offer us in this regard?
Numerous welding websites claim that making an electrode is not a problem. Without going into the details of such production, you will need a steel bar, chalk, crushed to a powder state (fine fractions). Liquid glass (silicate glue) is applied to the rod, then the whole thing is sprinkled with chalk and rolled so that it evenly adheres to the surface of the rod. The result is a chalky layer of some thickness. The homemade product is sent to the oven, oven or dried with a hairdryer.
And can you cook with this?
From our point of view it is impossible. You can just as easily cook with a nail, rebar or bare metal rod. There is no difference. The process of such welding is unstable, the seam can hardly be called such, and there will be practically no slag due to the absence of slag-forming elements in the composition of the coating.
If you are going to do it yourself, it is better to use the idea proposed a hundred years ago by two Americans. They came up with the idea of simply wrapping the bar in paper and gluing it on liquid glass. At least it's easier than messing around with chalk. And the idea is very simple. The paper burns and emits smoke, which protects against the harmful effects of oxygen. Also, such a coating somehow improved ignition and had a positive effect on the stability of the arc... And this, of course, is very doubtful. Since the easy ignition of an electric arc and the maintenance of its combustion occurs due to the low ionization energy of elements such as sodium, potassium and calcium.
In other words, you don’t have to worry about the composition of the coating and the method of application. If you really want to cook, but have nothing, and the shops are all closed for the holidays, take any piece of iron suitable in diameter and length, clamp it into the electrode holder and cook - this process cannot be called welding, but it is quite possible to grab something this way in extreme conditions. At the very least, this is no worse than the options proposed above.
The carbon contained in cast iron makes it difficult to weld. If the approach is incorrect, deep pores and cracks may appear at the joint, and in general, the workpiece being welded can easily be damaged.
For this reason, there are special requirements for welding cast iron, one of which is the use of the appropriate type of electrodes. Electrodes for cast iron differ in materials of manufacture. They can be made from cast iron rods, steel wire, and copper and its alloys.
This site article is about MMA welding mmasvarka.ru we will talk about what types of cast iron electrodes exist, and whether they can be made with your own hands, so to speak, at home.
Types of electrodes for welding cast iron
For welding cast iron products special types of electrodes are used. If steel wire was taken as the basis for their manufacture, then cast iron electrodes are marked as follows - SV-08 A and SV-08. There are also so-called universal types of electrodes for cast iron.
TsCh-4 - with electrodes of this brand you can obtain an even and strong welding joint on cast iron and products made from it. TsCh-4 electrodes are suitable for welding at almost any temperature.
EMES - for their manufacture, low-carbon wire is used, onto which a three-layer coating is applied during the manufacture of EMES electrodes. Due to this, during the burning of the electrode, a gas protective layer is formed, which protects the weld from the formation of air bubbles and oxidation.
Ficast NiFe K electrodes - a special type of electrodes for welding cast iron and steel together. They are iron-nickel rods for high-quality welding of cast iron and steel.
MNC-1 - electrodes of this series are made of an expensive alloy, which includes: copper, nickel and monel metal. Thanks to the use of these electrodes on cast iron, the seam is easy to further process, and no pores or cracks form on it.
How to make electrodes for cast iron with your own hands
The cost of electrodes for welding cast iron is quite high, and today it is quite difficult to find high-quality consumables for working with cast iron and products made from it. Therefore, many experienced welders resort to one trick: they make cast iron electrodes themselves.
To make them, you will need copper wire up to 2 mm, and the most common electrodes for welding, for example, the same UONI, ANO-4 orSSSI 13/45 . The process of converting conventional electrodes for welding cast iron is very simple. To make electrodes for cast iron with your own hands, you will need to screw copper wire to conventional electrodes. Thus, using ordinary electrodes, it will be possible to cook cast iron.
An equally popular method of making electrodes using cast iron and using the following components:
- Liquid glass;
- Copper rods, up to 5 mm in diameter;
- Metal powder and crushed electrode coating.
The process of making homemade electrodes for welding cast iron using these components is as follows:
- Copper rods are cut required length, after which they are thoroughly cleaned with fine sandpaper and degreased;
- A previously prepared and carefully crushed electrode coating is taken and mixed with fine metal filings (proportions: one to one). Then approximately 30% liquid glass is added to the resulting mixture;
- Next, cut copper rods are taken and dipped several times into homemade electrode coating until their coating becomes approximately 2 mm thick;
- The electrodes are then dried;
- And before welding cast iron, make sure that homemade electrodes are calcined in electric oven. The temperature for calcining electrodes on cast iron is approximately 200 degrees plus.
As you can see, making electrodes for welding cast iron is not at all difficult. Thus, you will not only save on consumables for welding, but also to achieve best quality performance of work.
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 welding work It’s quite possible to do it yourself. Especially in those places where the beauty of the seam is not required. We will tell you how to cook by welding correctly 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 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.
It's not really the right way welding)) At a minimum, you need
Types of electric welding
An electric arc can be formed by both direct and alternating current. AC current Welding transformers are welded, inverters are used as permanent ones.
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 circumstance, and neither is yours. household appliances may get hurt.
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 welding inverter.
Welding technology
For an electric arc to occur, two conductive elements with opposite charges are required. One is metal part, and the second is the 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 when special works 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 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).
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 it's quiet preparatory activities start welding.
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 welding machine, buy electrodes and a welding helmet and start practicing.
To reinforce the information, watch the video lesson on welding.
