Contents
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 is required to be welded or cut off. And if you can still cut off with a grinder, then there is nothing to reliably connect metal parts except for welding. And if the construction is done by hand, then welding work can be done independently. Especially in those places where the beauty of the seam is not required. About how to cook by welding, we will tell in this article.
The basics of electric welding
Welded metal joints today are the most reliable: 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 impact zone to the melting point, and this happens in a small area. Since an electric arc is used, welding is also called electric arc.
Types of electric welding
An electric arc can be formed by both direct and alternating current. Welding transformers are welded with alternating current, inverters with direct current.
Working with a transformer is more complicated: the current is alternating, therefore the welded arc “jumps”, the apparatus itself is heavy and bulky. Still a lot of annoying noise, which emits during operation and the arc and the transformer itself. There is one more nuisance: the transformer strongly “sets” the network. Moreover, significant voltage surges are observed. This circumstance is not very happy with the neighbors, 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. Neighbors won’t know you’ve started using a welding machine unless they see you. In addition, since the arc is caused by direct current, it does not jump, it 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 the metal part and the other is the electrode.
The electrodes that are used for manual arc welding are 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 different 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 an electric arc to the melting zone: the weld pool.
In the process, the protective coating also burns, partially melting, partially evaporating and releasing some 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, helping to maintain its temperature. In order to properly weld by welding, it is necessary to ensure that the slag covers the weld pool.
The weld is obtained 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 is formed on it – the result of the burning of protective gases. It also protects the metal from contact with the oxygen contained in the air. After cooling, it is beaten with a hammer. In this case, hot fragments scatter, therefore eye protection is required (wear special glasses).
You can read about how to make a brazier from a balloon or barrel here. Just get used to it.
How to learn to cook by welding
It all starts with the preparation of the workplace. When working with electric welding, special attention must be paid to safety: there is a possibility of injury from both electricity and high temperatures. Therefore, take preparation seriously.
Learning to cook with electric welding is more convenient on a thick piece of metal: it is better to practice on it. In addition to him and the welding machine, you will need leggings (thick gloves) and a welder’s mask. You also need tight clothing that protects the whole body, durable shoes of thick leather. They must withstand sparks and scale. You will also need a hammer and a metal brush in order to knock down the slag. You will need goggles to protect your eyes.
How to connect an electrode
Welding work for beginners will be easier to carry out if you take a universal electrode with a diameter of 3 mm (3,2 mm, to be exact). They cost more but are 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. With a screw clamp, the handle rotates. Unscrew it, insert the electrode and clamp it. Either way, it shouldn’t wobble. After installing the electrode, you can connect the cables.
There are two outputs on a DC welding machine: positive and negative. There are also two welding cables:
- one ends with a metal clip-lock – it is connected to the part;
- the other is an electrode holder.
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 fed to the electrode. This type of inclusion 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).
Straight polarity provides better heating of the metal, which is necessary for most connections. This is because the electrons move from the negatively charged pole – with direct polarity, this is the electrode – to the positive – the part. At the same time, they additionally transfer their energy to the metal, raising its temperature.
Start welding: ignite the arc
How to connect the electrode to the inverter figured out. Now about how to light the arc. It occurs when the electrode and the workpiece are in direct contact. There are two ways:
- strike;
- tapping.
Everything is clear from the name: in one case, you need to run the electrode along the seam (so that there are no traces left), in the second, hit the part with the tip of the electrode several times.
When the electrode is new, its tip is bare, ignition is easy. If it was already in operation, a wall of several millimeters of protective coating formed around the rod. This coating must be beaten off by tapping the part several times with the tip.
Both methods of ignition are used, here everyone chooses as it is convenient for him. This skill is the first one you will need 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 ignite the arc. Once you have become successful, you can proceed to the next stage of training.
The slope of the electrode
The main position of the electrode is tilted slightly towards itself at an angle of 30° to 60° (see figure). The slope value is selected depending on the required weld and on the set current. Focus on the state of the weld pool.
The first position is called the “back 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 get the heating of the metal to a great depth.
There are situations when the metal does not need to be strongly heated. Then the angle of inclination changes to the opposite, the seam and the bath “stretch” behind the electrode. In this case, the heating depth is minimal.
Electrode movements
The answer to the question “how to cook 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 you have to control several parameters at the same time:
- 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, speeding up 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.
How to learn to cook with electric welding? Practice movements on a thick piece of metal. It turns out then not the seams, but the rollers. This stage is the initial one. On it, you will master the elementary 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 trajectory, monitor the weld pool and the slag in it.
To do this, take a thick metal, draw a line on it with chalk: you will need to lay a roller along it. Fire up the arc and begin to master the movements, learning to control the bath at the same time. You will succeed not the first time, and not even the tenth time. You will probably exhaust a dozen electrodes. When the manual arc welding technique has been worked out: the roller will be uniform, its width and height will be constant (or almost), you can try to connect the parts.
How to make a gazebo on a metal frame, read in this article, and here the construction of a barn on a metal frame is described.
How to weld metal
Learning how to properly hold the electrode and move the bath is not enough for a good result. It is necessary to know some subtleties of the behavior of the joined metals. And the peculiarity lies in the fact that the seam “pulls” the parts, which can cause them to warp. As a result, the shape of the product can be very different from what was intended.
Therefore, before work, the parts are fixed with clamps, ties and other devices. In addition, tacks are made – short transverse seams laid through several tens of centimeters. They fasten the parts, giving the product a shape. When welding joints, they are applied on both sides: in this way, the resulting stresses are compensated. Only after quiet preparatory measures begin welding.
About the types of welds and joints (horizontal, vertical, ceiling) and how to cook them correctly, read here.
How to choose a current for welding
It is impossible to learn how to cook by electric welding if you do not know which current to set. It depends on the thickness of the parts to be 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 supply 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 electrode movement – several times passing through one place. Another way is to put a thinner electrode. By combining all these methods, a good weld can be achieved even under such conditions.
Now you know how to cook by welding. It remains to develop the skills. Choose a welding machine, buy electrodes and a welding mask and start practicing.
To consolidate the information and make fewer mistakes, watch the video tutorial on welding.