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

With all this control, you can achieve extremely durable welds with the highest quality finishes. Advantages Excellent welding welding Processing of welds with fewer welds Low sensitivity to intergranular corrosion No splashes Can be automated Cost of equipment very reasonable Consumables and accessories that are easily available on the market.

Limitations Difficulty of use in the presence of air flow Insufficient for welding plates of more than 6 mm, for which we have other more efficient processes. Low productivity due to the low deposition rate of the material. The process depends on the ability of the welder when it is not automated.

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

An excess of ultraviolet rays generated by welding, which, as ophthalmologists know, is called "Arc Radiation." One of the most common symptoms that indicate that you have “burned” your cornea is the feeling that someone is “poking” your eyes at night. The use of a “welding mask” is mandatory and optional. When welding with passers-by, it is recommended to use a curtain and do not forget to warn others, especially children and even small animals such as cats and dogs, as they can also be injured.

An example of curtain type protection in the welding section. The selected pairs are associated with the type of material being welded, current strength, welder ability, sheet cleaning, welding, section ventilation, etc. There are types of materials that can generate extremely toxic gases, for example, in zinc welding, and it is very important that the welder knows the variables of the object and prevent pollution. All this is cumulative, and the welding departments must have good ventilation or even exhaust fumes. Never weld indoors, as inside a garage.

Welding light produces a large amount of ultraviolet rays and can cause burns, as if you were exposed to the sun. It is also important to protect the face, hands, arms, legs. Since welding often “swings” with small pieces of hot metal, “scratches” are most noticeable.

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

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

This option is ideal for welding non-ferrous materials. With this type of welding, the electrode will alternate between positive and negative. carbon steel. Control panel element from left to right: torch connector Gas connector Burner female connector Negative clamping connector.

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

It will be refueled in a torch. at the bottom of it. Tighten tightly. Observe low torque with two pliers. But to break me, to pull me up, let's put the top of the torch. Pass the nozzle nozzle. It should be a good drain. Which can lead to contamination during welding. Which must be in good condition. To prevent leakage in the torch.

Now it's time to install the plug to observe what's next to the screw thread of the plug. Thus, it is at this moment that we adjust the “how much” of the tungsten electrode. Now we are with the torch mounted and ready to use. Connecting a negative claw now allows you to set a negative claw.

A heated weld already appears, completing the result. Let's wrap two parts of a stainless steel tube. From 3 mm of the initial wall. Concluding the final result, we weld two parts of a stainless steel tube. walls 3 mm. They are protected against atmospheric pollution with an inert gas. This process mainly relates to the production of ultrapure metals. With minimal melting and electrical discharge. Usually when welding aluminum. Increase electrode life. Iridium and cerium. Tungsten electrode.

Lanthanum. welding arc. thorium. The addition of these components to the tungsten electrode is usually carried out in proportions from 1% to 4%. It is a tungsten metal rod. Electrode and weld pool. Commonly used are metal oxides: zirconium. And be a great conductor of electrons. increased arc stability. They are produced by the metallurgical process of the highest level. It is called sintering. And is recognized for its effective benefits. Its melting point. Usually argon. All these oxides increase the ease of opening the arc.

Thorium has been used for many years. Zirconium is used with alternating current. Usually contains a small amount of other metal oxides. Helium gas is also an option. and the ability to intelligently handle the vast majority of welding work. and for value.

In Brazil. Thus allowing you to calculate how much gas you have spent or still have inside the cylinder. Partial or full reproduction is prohibited, outside the System, without the express permission of your regional department. The electrode and the pool of the melt 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 base metal. This is a process suitable for almost all metals, in particular titanium, zirconium, aluminum and magnesium alloys, alloy steels, stainless steels, nickel alloys and special alloys. This is a widely used process for welding pipes in the aerospace and nuclear industries and repair work due to the simplicity of process control and the possibility of using additional material. Advantages This process has the advantage of high quality welds, lack of slag and spatter and can be used in all positions and types of joints. In addition, tungsten is called thermionic, because it is easy to radiate electrons, which greatly facilitates the stability of the arc; tungsten can be pure or with zirconium or thorium alloys. Pure tungsten electrodes have the advantage of lower cost and smaller grinding when using alternating current. On the other hand, the disadvantages are the difficulty of opening the arch and lower durability. The chemical composition of the electrode. Chemical elements added to the electrode are important to ensure better welding performance. Zirconia or titanium dioxide electrodes have the advantages of increased durability, higher strength with higher potencies and better ignition properties. On the other hand, the disadvantages of using AC are higher cost, higher grinding effect and lower arc stability. The zirconia electrode has good characteristics when used with alternating current and is highly resistant to contamination. This preparation is performed by grinding the tip, always in the longitudinal direction, to facilitate the direction of electrons. In special cases, grinding marks are removed by polishing. When welding with direct current, the tip of the electrode should be pointed. The correct tip of the cone can be obtained by a practical rule: the height of the cone should be twice the diameter of the electrode. In the case of AC welding, the electrode tip should be slightly rounded. The choice of electrode. The choice of the type and diameter of the electrode should take into account the thickness and type of material, the type of connection, the number of passes and welding parameters, such as current strength and voltage, as well as the chemical composition of the electrode. The diagram helps to choose the electrode. The following parameters are considered: arc length, welding speed, gas flow and welding current. Arc length Arc length is the distance between the tip of the electrode and the base metal; Increasing the length also increases the arc voltage at a given welding current and this shielding gas. The length of the arc affects the weld, which will be the greater, the larger the arc. A very short or very long arc becomes unstable, which contributes to the formation of porosity, bites and lack of fusion. Welding speed Welding speed affects the penetration and width of the weld; Thus, if the speed increases, penetration and cord are reduced, and also strengthened when welding with the addition of metal. Increased speed improves the efficiency and productivity of welding, reducing production costs; However, too high speeds can cause tears, such as lack of penetration and bites. Gas flow For effective protection against gas, the gas flow must be considered. The flow must be strong enough to remove air from the weld zone and thus protect the melt pool; However, a high flow rate can cause turbulence in the gas flow, which leads to rupture or cord defects and arc instability, not to mention the higher cost of welding. There are 10 torch adaptive devices available on the market that provide a smoother and more efficient gas flow. The rule for determining the ideal flow rate is to conduct a test starting at a high flow rate and gradually decrease until surface oxidation of the cord begins; The ideal flow rate will be the closest and highest. The low flow rate does not provide adequate protection for the puddle, which also leads to rupture. 11 In the case of mechanized welding, rolled coils are used. Diameters of threads and threads are different. The materials and alloys used in the manufacture of sticks are different; They are classified by their chemical composition and by the properties of the deposited metal. It is important that the additive metal is free of moisture, fat and oxidation. The choice of additional metal. The choice of metal with the addition takes into account factors such as the similarity of the base metal, chemical composition, mechanical properties and reasonable costs. The diameter of the wire or probe should correspond to the thickness of the parts to be welded or the amount of material to be deposited. This information is available in manufacturers catalogs. Moisture content is also an important factor that needs to be controlled. The choice of gas depends on factors such as the type of metal being welded, the thickness of the parts, and the position of the weld. 70% and 30% and 30% and 70% of a mixture of argon and helium represent the best results when welding non-ferrous metals such as aluminum, magnesium and alloys. The choice of gas is important because it affects the welding speed. Helium requires high welding voltages, which requires higher energy with the same length of current and arc; Provides great penetration of the weld; It represents a high cost, but, in turn, provides a higher speed in the case of automatic welding of aluminum and its alloys. In the automatic welding of aluminum and its alloys, pure helium gas with direct current and negative polarity can be used. Consists of a source of electrical energy, which can be at the same time a transformer, in the case of alternating current or a rectifier or generator, in the case of direct current; Torch with a support for an electrode; Conductive cable for protective gas; One cable for the cooling system and one for power; a gas source, which can be a cylinder and a pressure regulator, or a set of cylinders with channels for supplying a distribution network in case of welding by several workstations; And a gas flow regulator. 15 The torch supports the tungsten electrode and also provides shielding gas. There is a clamp inside the torch that holds the electrode and should be selected according to the diameter of the electrode. The wide selection of torches available on the market allows you to adapt it to hard-to-reach welds. The burner nozzle, which may be ceramic or metal, has the function of directing the shielding gas; It should also be selected depending on the thickness and shape of the weld or the electric current used. The diameter of the gas nozzle must be large enough to adequately protect the molten puddle and the heated zone. The rule of thumb says that the inside diameter of the nozzle should be four times the diameter of the electrode. Torch cooling system Strong arc blasting and high currents require torch and welding cable cooling. This provides adequate protection, and the equipment becomes flexible and easy to handle. The torch can be cooled with water or air. Water cooling. The water used for cooling must be purified so as not to restrict or clog the aisles, which is why the equipment overheats and does not work. In cases where the available water is not purified, it is recommended to use filters. Most workshops have drinking water supply; However, sometimes work is performed in large workshops or in the field. 17 Air Cooling The torch can also be equipped with air cooling; This system is limited to a current of about 200 A, according to the manufacturer, and is used for welding thin plates with a very low duty cycle. An air-cooled burner is lighter and has a lower cost than a water supply system. The aperture is made using devices that form a type of pilot arc. The most often used high-frequency igniter, which provides a high-voltage and high-frequency signal of 5 kV and 5 kHz and allows ionization of the gas column between the electrode and the part, causing opening. A few seconds before the arc opens, it is recommended to start the flow of inert gas; This time interval is known as pre-gas leak. Then the arc is illuminated using a high-frequency igniter, and the torch is sent to a specific place to ensure the formation of the melting pool; When the puddle reaches the required size, welding may begin. A high-frequency signal has a very low power and does not affect operator safety. Gas bottle. Shielding gas is supplied in steel cylinders under pressure. Typically, devices have a device that prevents the ignition of sparks when opening the arc. This type of chain is used in welding steel, copper, chromium-nickel austenitic steels and heat-resistant alloys. 19 The concentration of heat is about 30% in part and 70% in the electrode. The resulting weld is wide with little penetration. The cleaning effect occurs when exposed to an electric arc: electrons leaving the base metal or gas ions bombard the oxide film, causing it to break. However, since positive polarity is little used, alternating current is usually used to cause this effect, since the breakdown of the oxide occurs in the positive half of the cycle. Electrons and ions go from part to electrode and vice versa, causing a balanced heat concentration of 50% for each and an average penetrating ball. Due to the rectification effect, an imbalance is observed 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 the appearance of two sinusoids of varying intensity. The rectifying effect is more damaging in the case of welding aluminum and magnesium, which are refractory oxide, because the flow of electrons emitted by the puddle is insufficient to completely destroy the oxide layer that exists during welding. To attenuate the rectification effect, a capacitor filter transformer is used, which balances the sine waves representing the electron flux. 21 Four main numbers, electrode identifiers have the following meanings: resistance corresponds to the tensile strength during welding in kilograms per square millimeter. The third digit changes from 1 to 4 and indicates the position in which the electrode can weld, where: 1 - all positions; 2 - all, except for the descending vertical positions; 3-apartment and horizontal layout; 4-flat position. When the calculation does not require accuracy, we can simply multiply the 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. Models vary from manufacturer to manufacturer, but the principle of operation of each type of machine is the same. Transformer for welding This is a static electric machine designed to supply AC electric arc. It can be small, medium and large depending on the work performed. Transformers, which are machines for welding with alternating current, allow you to use only electrodes suitable for this type of current. Note. For long-term operation and electrodes with a large diameter, care must be taken to select a machine with sufficient power. A machine usually has two pins for connecting cables. The transformer, in most cases, has a steering crank device in which the current intensity is regulated. In small machines, the intensity is adjusted using a pin connector, and the ground cable is inside. 29 It can be small, medium and large, depending on the requirements of the work performed. To control the intensity of the current, a lever is used, which is shifted between two scales graduated in amplifiers. Note: the generator contains rotating parts that are subject to wear; For this reason, a maintenance and lubrication plan must be established in accordance with the manufacturer's instructions. Welding rectifier This is a static electric machine designed to power a DC electric arc. The rectifier supports long-term operation thanks to a cooling device connected to its own housing. 31 The rectifier has two or three pins for connecting cables with polarity indicated. The rectifier has a flywheel or rheostat device, in which the current intensity is regulated. 32 Current control The current supplied by the machine must vary depending on the diameter of the electrode. When the electrode diameter is indicated in fractional inches, a general rule can be established to adjust the current. This rule: the current intensity of work with the coated electrode should approximately correspond to the diameter of the electrode core in milliseconds. Example. Decision. If for every 1 mm we use 40 A, multiplying 3, 2 mm by 40 A, we will find the approximate current strength for welding with an electrode with a diameter of 3.2 mm. Arc Length To determine this, the following rule applies: The length of the arc in welds with coated electrodes must 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 weld mirror less spatter Less penetration Spray welding Excessive spatter Advance speed It varies depending on the current intensity with the size of the part and the desired cord type. 34 Calculate and record the current intensity for working with an electrode 4 mm in diameter. 35 Types of electrodes An electrode can be of two types: bare or coated. It is covered. It consists of a metal core coated with organic and mineral compounds, an alloy of iron, etc. with certain percentages. The electrode may be extruded or simply sheathed and may be thin, medium or thick. The core material can be black or color, and its selection is made in accordance with the material of the part to be welded. Coating components are supplied in the form of a powder bonded with a “bonding” adhesive, usually with potassium or sodium silicate. It is used with benefits in the workplace: small to medium coverage. Which requires good craftsmanship. Finishing order 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, which we will give below, are less used than the three mentioned above. Acid Its coating consists of iron oxide, manganese oxide and other deoxidizing agents. The most recommended operating position for this electrode is flat. Its penetration is small, and its mechanical properties are very poor. It is used in workplaces where the appearance of the cord is more important than its resistance. Note: In some types of coating, metal particles are added that give the electrode other characteristics, such as: higher work efficiency; certain properties. Functions of coverage Functions of coverage are many. Then we will divide the most important and divide them into three groups. Electrical function Make the air between the electrode and the part more conductive, making it easier to pass electric current, which allows you to establish and maintain a stable arc. Metallurgical functions. Create a gas curtain that surrounds the arc and molten metal, preventing the harmful effects of air, and adding alloying elements and deoxidants to reduce impurities. Physical function Direct metal droplets to the melting pool, making it easier to weld in various positions and delaying ball cooling through slag formation, providing better mechanical properties of the weld. Thick, containing calcium carbonate, other basic carbonates and fluoride. It must be dry to avoid porosity in the weld. Thin, combustible organic materials that, when burned, produce a thick layer of protective gas. Medium or thick, containing iron oxide and manganese and other deoxidants. Thick, containing iron oxide without magnesium oxide. Melting rate Normal Regular High High High Penetration Small Medium Large Medium Small slag Dense and viscous, usually self-tapping. Compact and thick, easy to remove. Acid, easily detachable; Porous and friable. Heavy, compact and self-loading. Crack tendency Normal Low Regular High Normal Normal 41 May be in welding booths or other places where welding is required. Here are some precautions that must be observed in some of these places. The cabin should be painted dark and matte to avoid light reflection. It must be sufficiently ventilated so that the gases emitted by the electrode during welding are not absorbed by the welder; Although these gases are usually non-toxic, they can affect the airways. Field welding In this situation, in addition to the usual precautions, the welder should be aware of damage caused by electric current, avoid working in wet places, in the rain, barefoot or with shoes in poor conditions. Maintenance during welding Particular attention should be paid to welding in the vicinity of flammable or explosive materials. 43 Of the rays emitted by the most harmful, are ultraviolet and infrared. Ultraviolet rays Causes: severe burns, destruction of cells and at the same time premature destruction of the skin; Severe attack on the eyeball and can lead to catarrhal conjunctivitis, corneal ulcer, etc. infrared ray It is responsible for damage, such as: burns 1 and 2 degrees; cataract; frequent headaches; The look is tired. Infrared and ultraviolet rays are invisible. Spatter These are small drops of molten metal that jump in the welding process in all directions. They are responsible for burns on the welder, as well as for fires if they get on combustible material. 44 Masks for personal protective equipment They are made of non-combustible material, thermal and electrical insulation, light and durable. They serve to protect the welder from lightning, splashing and high temperatures that occur during welding. There are several models, and your choice should be made in accordance with the type of work performed. Light filters These are safety glasses that must absorb at least 99.5% of the radiation emitted during welding. Assembling glasses Assembling glasses in the mask should be performed as shown in the figure below. Apron Protects the front of the body. Leggings or Leggings Protect the welder's legs and feet. The concept of electricity used for welding. Safety and personal protective equipment. Variables that affect welding. Electrodes for manual arc welding. Classification and storage of electrodes. Welding technology - tigers process and coated electrode. . This is a welding process that uses an electric arc as a heat source between the part and the consumable in the form of a wire provided by a continuous feeder, which makes the connection of metal materials fusion.