Allpanel – Arc welding is a welding process used to join metal to metal by using electricity to create enough heat to melt the metal, and the melted metals, cooling, resulting in a bond of the metals. It is a type of welding that uses a welding power source to create an electric arc between a metal rod (“electrode”) and the base material to melt the metals at the point of contact. Arc welding power sources can provide direct (DC) or alternating (AC) current to the job, while using consumable or non-consumable electrodes.

The weld area is usually shielded by some form of shielding gas (for example, an inert gas), steam or slag. Arc welding processes can be manual, semi-automated or fully automated. First developed in the late 19th century, arc welding gained commercial importance in shipbuilding during World War II. Today it remains an important process for the production of steel structures and vehicles.



To provide the electrical power needed for arc welding processes, a number of different power sources can be used. The most common classification is constant current power supplies and constant voltage power supplies. In arc welding, voltage is directly related to the length of the arc, and current is related to the amount of heat input. Constant current power supplies are most often used for manual welding processes, such as gas tungsten arc welding and shielded metal arc welding, because they maintain a relatively constant current as the voltage varies. This is important because in manual welding, it can be difficult to keep the electrode perfectly stable and as a result the arc length and therefore the voltage TD can fluctuate. Constant voltage power supplies maintain constant voltage and vary current and, as a result, are most often used for automated welding processes such as gas metal arc welding, flux cored arc welding and submerged arc welding. . In these processes, the arc length is constant, because any fluctuations in the distance between the wire and the base material are quickly rectified by a large change in current. For example, if the wire and the base material get too close together, the current will increase rapidly, which in turn causes heat to rise and the top of the wire to melt, returning it to its original separation distance.

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Under normal arc light conditions, a constant current power supply with a stick electrode operates at about 20 volts.

The direction of the current used in arc welding also plays an important role in welding. Consumable electrode processes, such as shielded metal arc welding and gas metal arc welding, usually use direct current, but the electrode can be charged either positively or negatively. In general, the positively charged anode will have a higher heat concentration (about 60%).

“Note that for stick welding in general, the DC + polarity is most commonly used. It produces a good bead profile with a higher level of petrification. The DC- polarity results in less petrification and a higher rate of petrification. Electrode melting. It is sometimes used, for example, on thin sheet metal in an attempt to prevent it from burning out.”

“With few exceptions, electrode positive (reverse polarity) results in deeper penetration. Electrode negative (forward polarity) results in faster electrode fusion and therefore faster deposition rate.”

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Non-consumable electrode processes, such as gas tungsten arc welding, can use any type of direct current (DC) and alternating current (AC). However, with direct current, because the electrode only creates the arc and does not provide filler material, a positively charged electrode causes shallower welds, while a negatively charged electrode produces deeper welds.

Alternating current moves rapidly between the two, resulting in medium penetration welds. One disadvantage of AC, the fact that the arc must be regenerated after each zero crossing, was overcome by the invention of special power units that produce a square wave pattern instead of the normal sine wave, eliminating the low voltage period after zero crossings. and minimizing the effects of the problem.

Duty cycle is a welding equipment specification that defines the number of minutes, in a 10-minute period, during which an arc welder can be safely used. For example, an 80A welder with a 60% duty cycle should “rest” for at least 4 minutes after 6 minutes of continuous welding.


Failure to follow the duty cycle limitations may damage the forests. Commercial or professional grade welders typically have a 100% duty cycle.

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One of the most common types of arc welding is shielded metal arc welding (SMAW), which is also known as manual metal arc welding (MMAW) or jacketed arc welding. An electrical current is used to generate an arc between the base material and a consumer electrode rod or rod. The electrode rod is made of a material compatible with the base material being welded and is coated with a flux that emits vapors that serve as a shielding gas and provide a layer of slag, which protects the weld area from contamination. . The electrode core acts as a filler material, which makes a separate filler unnecessary. The process is very versatile, requiring little operator training and inexpensive equipment. However, the welding time is quite slow, because the consumer electrodes must be replaced often and because the slag, the residue of the flux, must be removed after welding.

Also, the process is generally limited to welding ferrous materials, although special electrodes have made welding of cast iron, nickel, aluminum, copper, and other metals possible. The versatility of this method makes it popular in a number of applications including repair and construction work.

Gas metal arc welding (GMAW), commonly called MIG (for metal/inert gas), is a semi-automatic or automatic welding process with a continuously fed consumable wire acting as the electrode and filler metal, along with a wire inert or semi- Automatically. Inert shielding gas is flowed around the wire to protect the weld site from contamination. Constant voltage direct current power supply is most commonly used with GMAW, but constant current alternating current is also used. With continuously fed filler electrodes, GMAW offers relatively high welding speeds; However, the more complex equipment reduces convenience and versatility compared to the SMAW process. Originally developed for welding aluminum and other non-ferrous materials in the 1940s, GMAW was soon economically applied to steels. Today, GMAW is commonly used in industries such as automotive for its quality, versatility and speed. Due to the need to maintain a stable layer of shielding gas around the weld site, it can be problematic to use the GMAW process in areas of high air movement, such as outdoors.

Flux Cored Arc Welding (FCAW) is a variation of the GMAW technique. FCAW wire is actually a thin metal tube filled with powdered flux materials. Sometimes an externally supplied shielding gas is used, but often the flux itself is relied upon to provide the necessary shielding from the atmosphere. This process is widely used in construction due to its high welding speed and portability.

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Submerged arc welding (SAW) is a high productivity welding process in which the arc is struck under a coating layer of granular flux. This increases the quality of the arc, because the flux blocks contaminants in the atmosphere. The slag that forms on the weld usually flakes off on its own and, combined with the use of a continuous wire feed, the weld deposition rate is high. The working conditions are much better than those of other arc welding processes, because the flux hides the arc and there is no smoke. This process is often used in industry, especially for large products.

Since the arc is not visible, it is usually automated. SO is only possible in positions 1F (flat fillet), 2F (horizontal fillet) and 1G (flat groove).

Gas tungsten arc welding (GTAW), or tungsten/inert gas welding (TIG), is a manual welding process that uses a non-consumable electrode made of tungsten, a mixture of inert or semi-inert gas, and a separate pad. Especially useful for welding thin materials, this method is characterized by a stable arc and high-quality welds, but requires great operator skills and can only be achieved at relatively low speeds. It can be used on almost all weldable metals, although it is most often applied to stainless steel and light metals. It is often used where the quality of welds is extremely important, such as in bicycles, aircraft and marine applications.


A related process, plasma arc welding, also uses a tungsten electrode but uses plasma gas to create the arc. The arc is more concentrated than the GTAW arc, which makes traverse control more critical and thus generally limits the technique to a mechanized process. Due to its stable current, this method can be used on a wider range of material thicknesses than the GTAW process and is much faster. It can be applied to all the same materials as GTAW except magnesium; Automated welding of stainless steel is an important application of this process. A variation on this process is plasma cutting, an efficient process for cutting steel.

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Other arc welding processes include atomic hydrogen welding, carbon arc welding, electroslag welding, electrogas welding and stick arc welding.

Some materials, especially high-strength steels, aluminum,