Welding of metals is the most common way of joining them in various sectors of the economy (construction, mechanical engineering, laying pipelines, etc.). In everyday life (at home, in the country, in the garage), we also meet with the need to use metal welding. To a non-specialist, this work seems incomprehensible, difficult and mysterious. Moreover, it is associated with a certain risk to life.
Let's see if this is true. How to weld metal by electric welding?
In the modern trading network there is a wide variety of welding machines, inverters, protective equipment for welding. They are available to anyone, therefore, by purchasing the appropriate equipment, you can perform these welding work yourself. It is only necessary to learn what metal welding technology is, what are the safety requirements. In addition, one must get the necessary welding practice.
Types of metal welding
In our time, many different technologies have been developed for how to weld metal. For example, you can use electronic and laser radiation, connect products with a gas flame and cook with ultrasound. But the most widely used energy source is the electric arc.
How to weld metal correctly? Welding of metals using electric welding machines or inverters refers to electric arc welding, in which obtaining a high temperature in the welding zone necessary for melting the metal and obtaining a strong connecting seam is achieved by an electric arc (up to 7000 degrees Celsius) capable of melting any metal.
Security requirements
The first thing you need to worry about before you properly weld the metal is your own safety during the work. Prepare and wear protective clothing (tight pants, jacket, safety shoes, suede or leather gloves). It will protect you from burns in case of possible splashing of molten metal. You should also prepare a special protective mask or welding shield - this will protect your eyes from damage from the light radiation of arc welding.
You should also worry about fire safety - remove all flammable materials and liquids from the welding site, prepare fire extinguishing agents for use (in the absence of special means, even a bucket of water will do), ensure ventilation of the room where the work will be carried out, especially from the front and back of the welding machine.
A mustread the instructions for use of the welding machine and follow all the recommendations given there.
Electrical Safety
Before trying to practice how to weld metal, you need to make sure that the parameters of the electrical network from which the welding machine is powered meet its requirements. Otherwise, other electrical appliances connected to the network may be damaged, not only for you, but also for your neighbors. This is especially true for transformer welding machines, which significantly affect the power supply network by the presence of voltage surges during the start of welding and increased electric current consumption when the electrode sticks at the welding site. In addition, the welding machine should be positioned so that it cannot fall, damage itself or cause damage to other people and objects during work. The wires connected to the device must have good insulation, have been straightened. Damage must be excluded.
Procedure for preparing for work
How to weld metal correctly? The place to be welded must be cleaned to the metal, be dry. It is forbidden to perform welding work in wet weather, in rain and at negative air temperatures. Welding machine and electrodes must not be allowed to get wet.
How to weld metal with electric welding?
Welding is carried out at constant voltage or at alternating voltage. Transformer welding machines provide welding with alternating voltage.
When welding with direct current, there are two options for connecting the welding machine. When the plus is connected to the mass, and the minus to the electrode (this is called direct polarity), the metal heats up more, the melting zone is created deep and narrow. This inclusion is used when welding thick metal and leads to economical consumption of electrodes. With the opposite inclusion (reverse polarity), the electrode heats up more strongly and is consumed faster, the melting zone turns out to be wide and shallow. Therefore, reverse polarity is only used when welding thin sheets of metal.
Distinctive features of inverters
How to cook metal with an inverter? Inverter welding machines convert the alternating voltage of an industrial network into a pulse train of a higher frequency and then form a direct voltage current. Due to the presence of an electronic circuit that implements these conversions, the inverter has little effect on the power supply during operation, has a smoother adjustment of the output voltage, and is characterized by low weight and dimensions. In terms of the quality of the resulting welding seam, the inverter is not inferior to other similar equipment. Therefore, welding inverters have recently become very widespread, when the prices for such devices have decreased. The advantage of such a device is the relative ease of use when welding.
How to choose an inverter
An important parameter of the inverter is the load period (PV) of the current source. This valuecharacterizing the efficiency of the inverter, shows the ratio of welding time to idle time. Household appliances do not work continuously. They must be cooled down periodically. So, an inverter duty cycle of 30% means that after every 3 minutes of welding, you have to wait 7 minutes for the source to cool down. If you try to continue working without interruption, the unit may burn out. Or the protection will work, and it will turn off. Therefore, you should choose an inverter with a duty cycle of at least 60% and a maximum current of at least 140 - 160 A.
Preparing to work with the inverter
To gain experience in how to properly weld metal with an inverter, it is recommended to work with metal at least 2-3 mm thick at first and use 3 mm electrodes. It is better to buy new electrodes. Old, stale, borrowed from others are likely to be damp and unusable.
How to weld metal correctly? If this is your first experience, first try to seam the surface of one piece of metal without welding it to another piece.
Let's consider the sequence of work.
First, you need to connect the electrode to its holder, and the ground wire to the workpiece to be welded using the terminal. The other ends of the wires must be connected to the outputs of the inverter in straight polarity.
Secondly, you need to turn on the machine and set its output parameters in accordance with the recommendations, depending on the thickness of the material to be welded and the selected electrode size.
The technology of metal welding provides that in order to heat the metal to the temperature necessary to obtain a high-quality weld, it is necessary to take an electrode corresponding to the thickness of the material. The thicker the latter, the greater the layer of metal it can heat up and the greater the current must be set on the inverter to form an electric arc. At the same time, the greater the current, the faster the metal melts and the faster the electrode is consumed. For a thin layer of metal at high current and a thick electrode, holes often form, the material burns through. If the current is too low, either an electric arc does not occur, or, if it occurs, a poor-quality seam is obtained, the so-called non-burnout.
The third thing to pay attention to is the formation of an electric arc. To do this, strike the end of the electrode at the place to be welded, like a match on a box, without removing the end of the electrode from the metal. When an arc occurs, a red spot forms on the metal. But this is not yet molten metal, but only a flux formed during the melting of the powder shell of the electrode. We must wait, holding the end of the electrode at a distance of 1-4 mm from the metal surface, until the metal at the place of the arc is heated until the formation of the so-called weld pool - a drop of molten metal, characterized by a bright orange color and trembling from the flow of current.
Fourthly, it is necessary to move the end of the electrode towards the seam by one or two millimeters, again holding it at the indicateddistance from metal. Again wait for the drop to form, and so on, moving along the weld being made. When the electrode touches the metal surface, a short circuit is created, the arc disappears, the inverter turns off the current. Therefore, when making a seam, one should try to maintain a constant distance between the end of the electrode and the metal surface, gradually bringing the electrode closer to it as it burns. Rather, the electrode does not burn out, but melts, the metal in the weld pool is formed mainly from the metal core of the electrode. The powder coating of the electrode surface, when melted, forms a flux and gases that prevent the flow of oxygen from the surrounding air to the welding site and the oxidation of the metal, as well as helping the process of forming a high-quality weld.
During the welding process, it is recommended to hold the electrode at an angle of about 30 degrees from the perpendicular to the part to be welded in order to form a compact weld pool, and you can clearly see the place of welding. The more the electrode is inclined to the workpiece during the welding process, the more elongated the spot of the heated metal surface will be in the opposite direction and the longer the formation of the weld pool at the same current strength. The narrowest spot of melting metal is achieved when the electrode is perpendicular to the metal surface. But in this case, it is difficult for the welder to observe the welding process. Therefore, this position is used only when welding in hard-to-reach places.
How to weld metal with an inverter?
Having practiced making a weld on a simple surface, you can begin to connect metal parts. The process is similar, the difference is that the part to be welded must first be fixed in the right place with a clamp or in another way, and when a weld pool appears, move the end of the electrode not directly along the seam, but in zigzag movements from the center of the seam towards first one, then the other details, gradually moving along the seam, connecting them in this way.
The main thing is that success comes with experience. By purchasing it, instead of using the services of third-party specialists (for quite a lot of money), you can learn how to do welding with your own hands. Good luck with your studies and work!
