Welding of metals is the most common way to connect them in various sectors of the economy (construction, engineering, pipelines, etc.). In everyday life (at home, in the country, in the garage), we also encounter the need to use metal welding. To a layman, this work seems incomprehensible, difficult and mysterious. Moreover, it carries a certain risk to life.
Let's see if this is so. How to cook metal by electric welding?
In the modern distribution network, there is a wide variety of welding machines, inverters, and protective equipment during welding. They are available to anyone, therefore, having bought the appropriate equipment, you can independently perform these welding works. It is only necessary to learn what metal welding technology is, what are the safety requirements. In addition, you must obtain the necessary practice of welding.
Types of metal welding
Nowadays, many different technologies have been developed on how to weld metal. For example, you can use electronic and laser radiation, combine products with a gas flame and cook with ultrasound. But the most widely used source of energy is an electric arc.
How to weld metal? Welding metals using electric welding machines or inverters refers to electric arc welding, in which the high temperature in the welding zone necessary for melting the metal and obtaining a strong connecting seam is achieved by an electric current arc (up to 7000 degrees Celsius), which can melt any metal.
Safety requirements
The first thing you need to worry about before you weld metal correctly is your own safety when working. Protective clothing should be prepared and put on (tight pants, a jacket, safety shoes, suede or leather gloves). It will protect you from burns in case of possible splashing of molten metal. You also need to prepare a special protective mask or welding shield - this will protect your eyes from damage by light radiation from arc welding.
You should also worry about fire safety - remove all flammable materials and liquids from the place of welding, prepare fire extinguishing agents for use (even if there is no special means, a bucket of water will do), provide ventilation of the room where the work will be done, especially from the front and back sides welding machine.
Be sure to read the instructions for use of the welding machine and follow all the recommendations there.
electrical safety
Before you try to learn in 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 from you, but also from neighbors. This is especially true for transformer welding machines, which significantly affect the supply network by the presence of voltage surges during the start of welding and increased consumption of electric current when the electrode sticks at the welding site. In addition, the welding machine should be positioned so that it cannot fall, be damaged by itself or cause damage to people and objects during work. Wires connected to the device must have working insulation, have been straightened. The possibility of damage to them must be excluded.
Preparation for work
How to weld metal? The place to be welded must be cleaned to metal and dry. It is forbidden to carry out welding work in wet weather, in rain and at freezing temperatures. Do not allow the welder and electrodes to get wet.
How to weld metal with electric welding?
Welding is carried out at constant voltage or at alternating. Transformer welding machines provide welding with alternating voltage.
When welding with direct current, two options for connecting the welding machine are possible. 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 the economical use of electrodes. With the opposite inclusion (reverse polarity), the electrode warms up more quickly and is consumed faster, the melting zone turns out to be wide and shallow. Therefore, the reverse polarity is used only when welding thin sheets of metal.
Distinctive features of inverters
How to cook metal inverter? Inverter welding machines convert the alternating voltage of the industrial network into a pulse sequence of a higher frequency and then generate a constant voltage current. Due to the presence of an electronic circuit that implements these transformations, the inverter has a small effect on the supply network during operation, has a smoother adjustment of the output voltage, and is characterized by a small weight and dimensions. The inverter is not inferior to other similar equipment in the quality of the weld obtained. Therefore, welding inverters have received recently, when the prices of such devices decreased, very widespread. The advantage of this apparatus is the relative ease of its use in welding.
How to choose an inverter
An important parameter of the inverter is the load period (PV) of the current source. This value, characterizing the efficiency of the inverter, shows the ratio of welding time to idle time. Household appliances do not work continuously. They should cool periodically. So, the PV value of 30% of the inverter means that after every 3 minutes of welding you have to wait 7 minutes until the source cools 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 PV 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 first recommended to work with metal at least 2-3 mm thick and use 3 mm electrodes. Electrodes are better to buy new. Old, stale, borrowed from others, with a high probability will be damp and unusable.
How to weld metal? If this is your first experience, first try making a seam on the surface of one piece of metal without welding it with another part.
Consider the sequence of work.
Firstly, it is necessary to connect the electrode to its holder, and the mass wire to the workpiece to be welded using the terminal. The other ends of the wires must be connected to the inverter outputs in direct polarity.
Secondly, you need to turn on the device and set its output parameters in accordance with the recommendations, depending on the thickness of the material being welded and the selected electrode size.
The technology of metal welding provides that for heating 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 larger the metal layer it can heat up and the greater the current must be installed 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 with a high current and a thick electrode, holes are often formed, burning through the material. If the current is too low, either an electric arc does not occur, or, when it occurs, a poor-quality seam, the so-called non-burnout, is obtained.
The third thing you should 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 in 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 molten metal, but only a flux formed during the melting of the powder coating of the electrode. It is necessary to wait, holding the end of the electrode at a distance of 1-4 mm from the metal surface, until the metal in the place of the arc warms up to form the so-called weld pool - a drop of molten metal, characterized by a bright orange color and shaking from the flow of current.
Fourthly, it is necessary to shift the end of the electrode towards the performed seam by one or two millimeters, again keeping it at the indicated distance from the metal. Wait again for the formation of droplets, and so on, moving along the weld being performed. When the electrode touches the metal surface, a short circuit is created, the arc disappears, the inverter shuts off the current. Therefore, when making a seam, you must try to maintain a constant distance between the end of the electrode and the surface of the metal, gradually approaching the electrode to it as it burns. Rather, the electrode does not burn, 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 molten, forms flux and gases that impede the flow of oxygen from the ambient air to the weld site and the oxidation of the metal, as well as help the formation of a high-quality weld.
In the process of welding, it is recommended to hold the electrode at an angle of about 30 degrees from the perpendicular to the part to be welded so that a compact weld pool is formed, and the place of welding is clearly visible to you. The stronger the electrode is inclined to the part during the welding process, the more elongated in the opposite direction will be the spot of the heated metal surface 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 surface of the metal. 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 trained in the implementation of the weld on a simple surface, you can proceed to the connection of metal parts. The process is similar, the difference is that the welded part must first be fixed in the right place using a clamp or in another way, and when the weld pool appears, move the end of the electrode not directly along the seam, but in zigzag movements from the center of the seam to one side, 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, you can instead of using the services of third-party specialists (for quite a lot of money) learn how to do welding work with your own hands. Good luck with your training and work!