The electric arc is ignited by a spark generator between the electrode and the detail. The electrode is only a terminal of one of the poles and is not added to the melting pool. Therefore, electrodes with high melting point and high emissions are used. For soldering steel, copper, nickel, titanium, etc. A direct current with straight polarity is used when the electrode is heated minus reverse polarity. Aluminum and its alloys are usually welded with alternating current. The alternating current gives an arc that cleans the plate in the positive cycle, which makes it easy to flow.

With all this control, you can achieve extremely resistant welds with the highest quality finish. Advantages Excellent welding welding processing of welds with fewer welds Low sensitivity to intercrystalline corrosion Without bursts, the cost of equipment can be automated. Very reasonable consumables and accessories, easily available on the market.

Restrictions The difficulty of use in the presence of an air flow is insufficient for welding plates more than 6 mm for which we have other more effective processes. Low performance due to low material deposition speed The process depends on the ability of the welder when it is not automated.

If you look directly on the welding arc, even on a short timeThis can lead to the burns of your cornea, which is extremely sensitive to bright lights, for example, directly looking at sunlight, snow, bright reflections, etc. Technically, the arc radiation causes inflammation in the cornea caused.

An excess of ultraviolet rays generated by welding, which is known to ophthalmologists, is called the "arc radiation". One of the most common symptoms pointing to the fact that you "burned" your cornea is the feeling that someone "pokes" your eyes at night. The use of "welding mask" is mandatory and optional. During welding with passersby, it is recommended to use the curtain and do not forget to warn others, especially children and even small animals, such as cats and dogs, as they can also suffer.

An example of a curtain type protection in the welding section. Selected pairs are associated with the type of material welded, current, the ability of the welder, the cleaning of the sheet, welding, ventilation of the site, etc. There are types of materials that can generate extremely poisonous gases, for example, with zinc welding, and it is very important that the welder knew the object variables and prevented contamination. All this is cumulatively, and welding departments must have good ventilation or even exhaust gases. Never weld indoors as inside the garage.

Welding light produces a large number of ultraviolet rays and can cause burns as if you were exposed to the sun. It is also important to protect the face, hands, hands, legs. Since welding often "waving" with small pieces of red metal, the most notisable are "scratches".

Usually found in workshops and industries. Not to mention the flammable solvents and paints. Therefore, before starting welding. Remember that foam or aqueous fire extinguishers are not recommended for obvious reasons: electricity of welding machines and their installations. This is a fact that much has already burned, trying to free the seals of fire extinguishers.

Offices and industries are often noisy places, and the use of dampers in accordance with the status of location is important. But if you have more than one. It is used for steel welding. Only the soldering machine cannot be noisy. stainless steel.

This option is ideal for welding colored materials. With this type of welding, the electrode will be alternate between positive and negative. Carbon steel. Control panel element from left to right: torch connector Gas connector Burner slot negative clamping connector.

These are connectors that connect torch with equipment. One for gas and one to run a trigger. On the front of the device. Gas connector trigger connector. Where all connections will be connected. We have from left to right. Time to assemble the electrode. Electrode. We will initially place a diffuser on the torch of the diffuser.

It will be charged in a torch. At the bottom of him. Tighten tightly. Observe a small torque with two pliers. But to break me to tighten, let's put the top of the torch. Skip the nozzle nozzle. It should be good leak. What can lead to contamination during welding. Which should be in good condition. To prevent leakage in a torch.

Now it's time to set the plug to watch that next to the screw thread forks. Thus, it is at this moment that we regulate how many tungsten electrodes. Now we are a torch mounted and ready to use. Connecting a negative claw now allows you to install a negative claw.

Already appears heated welded seam, the final result. Let's wrap the two parts of stainless steel tube. Of the 3 mm of the elementary wall. Completing the final result, we weld the two parts of stainless steel tube. Walls 3 mm. They are protected from atmospheric pollution with inert gas. This process is mainly related to the production of ultra-grate metals. With minimal melting and electric erosion. Usually when welding aluminum. Increase the service life of the electrode. Iridia and cerium. Tungsten electrode.

Lanthanum. welding arc. thorium. Adding these components tungsten electrode is usually carried out in proportions from 1% to 4%. It is a rod of tungsten metal. Electrode and welding bath. Metal oxides are usually used: zirconium. And be an excellent electron conductor. Increased arc stability. They are produced by the metallurgical process itself high level. Called "sintering". And it is recognized for its effective advantages. Its melting point. Usually argon. All these oxides increase the simplicity of opening an arc.

The thorium is used for many years. Zirconium is used with alternating current. Usually contains a small number of other metal oxides. Gas "helium" is also an option. And it is also possible to reasonably process the vast majority of welding work. And for value.

In Brazil. Thus, letting you calculate how much gas you spent or still have inside the cylinder. Partial or full playback is prohibited outside the system, without direct resolution of your regional department. The electrode and the melt pool are protected by a gaseous atmosphere consisting of an inert gas, that is, a gas that does not react with other materials, or a mixture of inert gases, usually argon or helium. Depending on the use of solder, you can add material to the melt; In this case, the material must be compatible with the main metal. This is a process that is suitable for almost all metals, in particular titanium, zirconium, aluminum and magnesium alloys, alloyed steels, stainless Steel, nickel alloys and special alloys. This is a widely used process of welding pipes in the aerospace and nuclear industry and repair work due to the simplicity in the management of the process and the possibility of using additional material. Advantages This process has the advantage of high-quality welds, no slag and splashing and can be used in all positions and types of connections. In addition, tungsten is called thermoelectronic, since it is easy to emit electrons, which greatly facilitates the stability of the arc; Tungsten can be clean or with zirconium or thorium alloys. Pure tungsten electrodes have an advantage in reducing costs and smaller grinding when using AC. On the other hand, disadvantages are the difficulty of opening the arch and lower durability. Chemical composition of the electrode. Chemical elementsAdded to the electrode are important to ensure the best performance of the welding process. Electrodes with the addition of zirconium dioxide or titanium have such advantages as increased durability, higher strength with higher potencies and better inflammation properties. On the other hand, the disadvantages when using AC are higher cost, higher grinding effect and lower arc stability. The electrode with zirconium dioxide has good characteristics When used with alternating current and has high resistance to pollution. This preparation is performed by grinding the tip, always in the longitudinal direction, to facilitate the direction of electrons. In special cases, grinding tags are removed by polishing. With a constant current welding, the electrode tip must be pointed. The correct cone tip can be obtained by practical rule: the height of the cone must be twice as the diameter of the electrode. In the case of alternating current welding, the tip of the electrode must be slightly rounded. Select the electrode. The choice of type and diameter of the electrode must take into account the thickness and type of material, the type of connection, the number of passages and the parameters of welding, such as the current and voltage, as well chemical composition Electrode, the diagram helps select the electrode. The following parameters are considered: arc length, welding speed, gas consumption and welding current. Arc length The length of the arc is the distance between the tip of the electrode and the main metal; Increasing the length also increases the arc voltage under a given welding current and this protective gas. The length of the arc affects the welded seam, which will be the greater the more arc. A very short or very long arc becomes unstable, which contributes to the formation of porosity, bites and the absence of merging. Welding speed welding speed affects penetration and width welded seam; Thus, if the speed increases, the penetration and cord are reduced, and also enhanced when welding with the addition of metal. Increased speed improves welding efficiency and productivity, reducing production costs; However, too high speeds can cause gaps, such as the absence of penetration and bites. The gas flow for efficient gas protection must be taken into account the gas flow. The flow should be strong enough to remove the air from the welding zone and thus protect the melt pool; However, high flow rate can cause turbulence in the gas stream, which leads to a rupture or defects of the cord and the instability of the arc, not to mention the higher welding cost. There are 10 adaptive devices with a torch that provide a smoother and efficient gas flow. The rule to determine the perfect flow rate is to test, starting with high flow and gradually decrease until the surface oxidation of the cord is started; The perfect consumption will be the closest and highest. Low consumption does not ensure adequate protection of the melting puddle, which also leads to a rupture. 11 In the case of mechanized welding, rolled coils are used. The diameters of the threads and threads are different. Materials and alloys used in the manufacture of sticks are different; Classified according to their chemical composition and the properties of the precipitated metal. It is important that the addive metal cannot contain moisture, fat and oxidation. Selection of extra metal. The choice of metal with the addition takes into account factors such as the similarity of the base metal, the chemical composition, mechanical properties and reasonable costs. The diameter of the wire or measuring probe must comply with the thickness of the welded parts or the amount of material to be treated. This information is available in manufacturers directory. The moisture content is also an important factor that needs to be monitored. The choice of gas depends on factors such as the type of welded metal, the thickness of the parts and the position of the welding. 70% and 30% and 30% and 70% of argon and helium mixture represent top scores When welding non-ferrous metals, such as aluminum, magnesium and alloys. Gas selection is important because it affects the welding speed. Helium requires high welding stresses, which requires higher energy at the same current and arc length; Provides a large penetration of the weld; Represents a high cost, but, in turn, provides more high speed In the case of automatic welding of aluminum and its alloys. With automatic welding of aluminum and its alloys, it is possible to use pure helen gas with a constant current and negative polarity. Consists of an electrical source that can be at the same time a transformer, in the case of an AC or a rectifier or generator, in the case of DC; Torch with a support for the electrode; Conductive cable for protective gas; One cable for cooling system and one for power; a gas source that can be a cylinder and pressure regulator, or a set of cylinders with channels for supplying a distribution network in the case of welding with several workstations; And gas flow control. 15 The torch serves as a support for a tungsten electrode, and also provides protective gas. Inside the torch there is a clamp that holds the electrode, and it should be selected according to the electrode diameter. A wide selection of torches available on the market allows you to adapt it to hard-to-reach welds. The burner nozzle that can be ceramic or metal has a function of the direction of protective gas; It should also be chosen depending on the thickness and form welding seam or electric current used. The gas nozzle diameter should be large enough to adequately protect the molten puddle and the heated zone. The practical rule says that the inner diameter of the nozzle must be four times larger than the diameter of the electrode. The torch cooling system is a strong arc blowing and large currents require the cooling of the torch and the welding cable. This ensures adequate protection, and the equipment becomes flexible and easy to handle. Torch cooling can be carried out with water or air. Water cooling. Water used for cooling must be cleaned to not limit or score passages, which is why the equipment overheats and does not work. In cases where available water is not cleared, it is recommended to use filters. In most workshops there are drinking water supply; However, sometimes work is performed on large workshops or in field conditions, 17 air cooling torch can also be equipped with air-cooled; This system is limited to a current of about 200 A, according to the manufacturer, and is used when welding thin plates with a very low operating cycle. The air-cooled burner is easier and has a lower cost than the water supply system. Aperture is made using devices that form a type of pilot arc. The most commonly used high-frequency igniter, which provides a high-voltage and high-frequency signal of 5 kV and 5 kHz and allows ionizing the gas column between the electrode and part, causing opening. A few seconds before the opening of the arc, it is recommended to start the inert gas stream; This time interval is known as a pre-leakage of gas. The arc is then illuminated with the help of high-frequency igniter, and the torch is sent to a specific place to ensure the formation of a melting pool; When the puddle reaches the desired size, welding can begin. The high-frequency signal has very low power and does not affect the safety of the operator. Gas cylinder. The protective gas is supplied in steel cylinders under pressure. Usually devices have a device that prevents the ignition of sparks when opening an arc. This type of chain is used in welding steel, copper, chromonichel austenitic steels and heat resistant alloys . 19 The heat concentration is about 30% in part and 70% in the electrode. The resulting weld seam is wide, with a small penetration. The cleaning effect occurs when exposed to an electrical arc: electrons leaving the base metal or gas ions, bombard the oxide film, causing its destruction. However, since the positive polarity is used little, the alternating current is usually used to cause this effect, since the oxide breakdown occurs in a positive half of the cycle. Electrons and ions come from the part to the electrode and vice versa, causing a balanced heat concentration of 50% for each and the average penetrating ball. Due to the effect of straightening, there is an imbalance in this movement, which leads to the fact that the emission of electrons from the fusion pool is less than the emission of electrons from the electrode; This causes two sinusoid of various intensity. The straightening effect is more destructive in the case of welding aluminum and magnesium, which are a refractory oxide, since the flow of electrons emitted by the puddle is not sufficient to completely destroy the oxide layer that exists during welding. To attenuate the effect of straightening, a condenser filter transformer is used, which bales sinusoidal waves representing the electron flow. 21 Four main numbers, electrode identifiers have the following meaning: The resistance corresponds to the strength limit when welding in kilograms per square millimeter. The third digit varies from 1 to 4 and indicates the position in which the electrode can weld, where: 1 is all positions; 2 - all except descending vertical provisions; 3-apartment and horizontal layout; 4-flat position. When the calculation does not require accuracy, we can simply multiply a constant 0. There are three main types of machines for welding with a coated electrode: a transformer for welding; Generator for welding; Rectifier for welding. The models vary from the manufacturer to the manufacturer, but the principle of operation of each type of machine is the same. A welding transformer is a static electric machine intended for supplying an electrical arc of AC. It can be small, medium and large depending on the work performed. Transformers that are machines for alternating current welding make it possible to use only electrodes suitable for this type of current. Note. For long-term work and electrodes with a large diameter, care must be taken to choose a machine with sufficient power. The car usually has two contacts for connecting cables. The transformer, in most cases, has a steering crank device, in which the current intensity is adjusted. In small machines, the intensity adjustment is performed using a pin connector, and the grounding cable is inside. 29 It may be small, medium and large, depending on the requirements of the work performed. To regulate the current intensity, a lever is used, which is shifted between two scales, graded in amplifiers. Note: The generator contains rotating parts to be worn; For this reason, the service and lubrication plan must be installed in accordance with the manufacturer's instructions. Welding rectifier This is a static electric machine designed to power the electrical arc with a constant current. The rectifier supports long-term operation due to the cooling device connected to its own body. 31 The rectifier has two or three contacts for connecting cables, where polarity is indicated. The rectifier has a device of a flywheel or a row, in which the current intensity is adjusted. 32 Current Adjustment The current supplied by the machine must vary depending on the diameter of the electrode. When the diameter of the electrode is specified in a fractional inches, a general rule can be set to adjust the current. This rule: the current intensity of the coated electrode should approximately correspond to the diameter of the electrode core in milliseconds. Example. Decision. If we use 40 A for every 1 mm, multiplying 3, 2 mm at 40 A, we will find an approximate current for welding with an electrode with a diameter of 3, 2 mm. Dougie Length To determine this, the following rule applies: arc length in welded seams With coated electrodes should be equal to or slightly less than the diameter of the electrode core used. In the following table, we can observe some differences in welding when working with a short or long arc. Short arc long arc High penetration less welded mirror less splashing less penetration spray welding Excessive splashing speed of advancement It changes depending on the current intensity with the size of the part and the desired cord type. 34 Calculate and write down the current intensity to work with an electrode with a diameter of 4 mm. 35 Types of electrodes electrode can be of two types: naked or coated. It consists of a metal core, covered with organic and mineral compounds, iron alloy, etc. with certain percentages. The electrode can be covered with extrusion or simply covered with a shell and can be thin, medium or thick. The core material can be black or color, and its choice is made in accordance with the material of the part to be welded. The coating components are supplied as a powder connected by the "binder" glue, usually with potassium or sodium silicate. It is used with the benefits of workplaces: small and medium coating. Which requires good skill. Order finishes with metal frames. Cellulose contains combustible organic materials in the coating. It is widely used for welding, where: penetration is very important; Slag inclusions are undesirable. Two types of electrodes that we will bring below are less used than the three mentioned above. Its coating consists of iron oxide, manganese oxide and other deoxidizers. The most recommended working position for this electrode is flat. Its penetration is small, and its mechanical properties are very bad. It is used in workplaces where appearance The cord is more important than its resistance. Note: In some types of coating, metal particles are added, which give the electrode, other characteristics, such as: Higher performance efficiency; Certain properties. Functions covering the function of the coating a lot. Then we divide the most important and divide them into three groups. Electrical function Make air between the electrode and the part more conductive, facilitating the passage of the electric current, which allows you to install and maintain a stable arc. Metallurgical functions. Create a gas veil that surrounds the arc and molten metal, preventing the harmful effects of air, as well as adding alloying elements and deoxidants to reduce impurities. Physical function Direct metal droplets to a melting basin, facilitating welding in various positions and holding down the cooling of the ball through the formation of slag, providing the best mechanical properties of the weld. Thick, containing calcium carbonate, other main carbonates and fluorine. It should be dry to avoid porosity in the weld. Thin, containing combustible organic materials, which, when burning, give a thick layer of protective gas. Middle or thick, containing iron oxide and manganese and other deoxidants. Fat, containing iron oxide without magnesium oxide. Melting Melting Speed \u200b\u200bRegular regular high high high penetration small medium large medium small slag is dense and viscous, usually self-tapping. Compact and thick, easily removed. Acid, easily separated; Porous and loose. Heavy, compact and self-charge. Creation Trend The usual low regular high normal 41 may be in welding cabins or in other places where welding must be performed. We give the precautions that need to be observed in some of these places. The cabin must be painted in dark and matte to avoid reflection of light. It must be ventilated enough so that the gases secreted by the electrode during welding are not absorbed by the welder; Although these gases are usually not toxic, they can affect the respiratory tract. Field welding in this situation, in addition to the usual precautionary measures, the welder should be aware of damage caused by electric shock, avoid working in wet places, in the rain, barefoot or with shoes in bad conditions. Maintenance When welding, special attention should be paid to welding near flammable or explosive materials. 43 of the rays emitted by the most harmful are ultraviolet and infrared. Ultraviolet rays Causes: Strong burns, cell destruction and at the same time premature skin destruction; Heavy attack on eyeball and can lead to catarrhal conjunctivitis, cornea ulcers, etc. The infrared beam is responsible for damage, such as: burns 1 and 2 degrees; cataract; frequent headaches; View tired. Infrared and ultraviolet rays are invisible. Splashes are small drops of molten metal, which jump in the process of welding in all directions. They are responsible for burns on the welder, as well as for fires, if they fall into combustible material. 44 masks for individual protective equipment They are made of non-combustible material, thermal and electrical insulation, light and stable. They serve to protect the welder from lightning, splashing and high temperaturesarising during welding. There are several models, and your choice must be performed in accordance with the type of work performed. Light filters are safety glasses that should absorb at least 99, 5% emissions emitted during welding. Assembling points Assembling points in the mask must be performed, as shown in the figure below. Apron protects the front of the body. Leggings or Leggings Protect the legs and feet of the welder. The concept of electricity used for welding. Security and personal protective equipment. Variables that affect welding. Electrodes for manual arc welding. Classification and storage of electrodes. Welding technology is the process of tigers and a coated electrode. . This is a welding process that uses an electric arc as a heat source between the part and the conductive wire in the form of a wire provided by a continuous feeder, which makes the connection of metal materials by fusion.