What is Arc Welding?

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Arc welding is a form of welding that uses an electric arc to melt metals together. 

It is a highly flexible process that can be used to weld together almost any metal, including alloys. 

Arc welding is a very popular process and is used for welding a variety of objects ranging from pipes and railings to cars, bridges, and spaceships.

Arc welding is an arc discharge process that uses an electric current to provide heat for welding.

The continuous electrical arc creates the melting point needed for brazing, and it also provides the necessary penetration for fillet welds. 

There are four basic types of arc welding processes

  1. Stick
  2. TIG
  3. MIG
  4. Flux-cored wire

The fifth method of electric resistance spot welding utilizes a non-consumable electrode or contact tip with an active gas shield as the heat source and is not strictly classified as a form of arc welding but shares many common characteristics.

Stick (also known as manual metal arc or MMA) is a manual process that requires skill to achieve consistent results. It is rarely used in industry due to its need for high amounts of skill and dexterity.

What Are The Types Of Arc Welding?

The arc of an electric arc welding process can be shielded by different means:

Shielded metal arc welding (SMAW) is one of the most common arc welding processes. 

A continuous electrical arc is formed between an electrode and the workpiece or between the electrode and a metallic electrode called a “stickout.” 

The melted filler metal adheres to both parts being joined and solidifies to form a puddle. 

Shielding gas is typically added to the weld puddle, and the gas protects the molten metal from atmospheric contamination during solidification.

Shielded metal arc welding is commonly used to join ferrous metals, but it can also be used to join nonferrous or nonferric materials.

SMAW uses electrode tips, but no consumable electrodes are usually found in a typical manufacturing shop.

It can be performed with any electrical potential from 100 volts up to very high voltages, depending on the type of electrode used. SMAW is similar to MIG welding in that it produces little spatter and does not require shielding gas and compressed air. 

In fact, it does not require any consumable shielding gas. SMAW welding uses lower amperage requirements than MIG welding and is typically performed at 50 to 60 V. It produces a rough surface, like a cob or ball joint, and is commonly used for joining ferrous metals. 

In the past, SMAW was widely used for joining nonferrous metals such as aluminum, copper, zinc alloys, or zinc-coated copper alloys.

SMAW provides good penetration of materials with a good weld appearance. Still, the weld metal has to be protected from atmospheric contamination by a gas that combines two or more oxides in a molten state (typically titanium dioxide and zirconium oxide). 

Gas tungsten arc welding (GTAW) is similar to TIG welding, except it uses filler metal electrodes instead of solid rods. 

The filler metal electrode usually comes in stick form and resembles a large wood screw. The procedure for GTAW is quite similar to TIG. Like TIG, GTAW is also a manual welding process and requires skill from the welder; if it’s not performed correctly, it may be difficult to correct at a later stage.

GTAW uses a constant current power supply, which produces a stable arc between the welding electrode and the base material. 

The weld area is protected from atmospheric contamination by a gas that combines two or more oxides in a molten state (typically titanium dioxide and zirconium oxide). 

The procedure for GTAW is quite similar to MIG welding, with a few slight differences. Unlike TIG welding, GTAW does not require a negative or positive lead and therefore requires no shielding gas, although it does require compressed air to purge the weld area of residual gases. 

This improves productivity as well as reducing the risk of contamination when using a gas environment.

GMAW also uses a constant current power supply, which produces a stable arc between the weld electrode and the base material. 

The weld area is protected from atmospheric contamination by a gas that combines two or more oxides in a molten state (typically titanium dioxide and zirconium oxide). If the weld metal becomes contaminated with atmospheric gases, the weld bead surface will appear pitted and have inadequate corrosion resistance. 

If the contamination is severe, a “tiger stripe” effect can form on the weld bead surface producing a brittle structure with poor fatigue properties.

The welding procedure for GMAW may be similar to either SMAW or MIG welding but does not require any shielding gas other than compressed air.  

This is to purge the weld area of residual gases; like GTAW, it also does not require any negative lead or positive lead. 

This improves productivity but also reduces the risk of contamination.

Types of GMAW Welding

The GMAW process uses a constant current power supply, which produces a stable arc between the weld electrode and the base material. 

The weld area is protected from atmospheric contamination by a gas that combines two or more oxides in a molten state (typically titanium dioxide and zirconium oxide).

The main advantage of GMAW over SMAW is that you don’t need an inert gas (argon, helium, or mixture) to protect the weld area from atmospheric contamination. 

This means that fumes from other welding processes or electric equipment won’t contaminate your area. GMAW with no shielding gas usually produces a higher weld quality than MIG welding but at a higher cost since you need more consumables (wire size and length).

Related: Best Arc Welders

Arc Welding Advantages And Disadvantages

GMAW can be made more productive than SMAW by using a short-circuiting technique, which is where the electrode sticks directly onto the workpiece. There are four ways that GMAW with no shielding gas can be used:

A key advantage of GMAW over GTAW is the greater ease of electrode manipulation. 

In GTAW, the arc needs to be manipulated to maintain the desired bead profile and some control over penetration depth. 

Since there is no molten pool in GMAW, there are much fewer undercut and attendant problems. This allows the operator to focus on the bead profile rather than maintaining a stable arc.

It is possible to maintain a much better profile in GMAW than in GTAW.

A disadvantage of GMAW over MIG welding is the welding characteristics for thinner material. 

In order to obtain a weld with acceptable quality and strength, the wire must be considerably thinner than required for MIG welding.

Due to this, GMAW should not be used for non-critical applications where electrodes are thin. 

Also, due to the lower amount of heat provided by the GMAW process, it is rarely used in fabrication or construction because it is slower than other processes such as shielded metal arc welding and gas tungsten arc welding.

The following table compares the current production processes (descending current production) and their respective costs.

GMAW is used in small batches for applications requiring materials with specific properties or characteristics, with the process being applied to materials with high tensile strength, low melting point, and corrosive. 

The higher cost of GMAW has decreased its use by manufacturers, but it continues to be used on specialized production lines by high volume producers. It is also used in vacuum arc welding for producing nails and screws.

While GMAW is a very versatile technique, some limitations may affect the quality of parts produced with this method.

Shielding gas can present issues since the shielding gas flow is dependent on the movement of the weld. Shielding gas flow is also reliant on amperage. There can be problems with non-uniformity and spatter over large areas. 

GMAW has a tendency to more easily generate porosity than other methods because of the high heat input during welding.

The main objective of GTAW (gas tungsten arc welding) is to provide a long, narrow fusion zone as opposed to a wide, shallow, or deep trench which would occur in SMAW. 

The narrow fusion zone allows for greater control over bead profile and penetration than possible with spray arc welding.

GTAW can be performed with or without filler metal. When GTAW is used without filler, it is called gas tungsten arc welding.

If the weld is made with filler metal, it is known as gas tungsten arc welding with filler. The term gas metal arc welding (GMAW) has been used to describe both GTAW and GMAW. 

Since the procedures are similar, they have often been confused for one another. GMAW can be applied over a wide range of thicknesses and provides greater control than spray arc welding (SMAW) over bead profile and penetrations.

What Is Arc Welding Good For?

Many people ask, “What is arc welding good for?”. As it turns out, there are a lot of benefits to this type of welding. For one thing, metal pieces that have been welded together are more robust than those which were simply stuck together. 

This is because the actual welding process adds something to the metal which cannot be gained through gluing or bolting. This new material can also be placed in any position without fear of cracking or breaking.

Arc welding has many applications in various industries, including construction and automotive repair and shipbuilding and aerospace engineering projects. 

It offers a clean cut on the material and doesn’t require more than one person to complete a weld successfully. It’s fast, and its final results are almost unbeatable.

For a reliable weld, the project must be planned out properly, and the metal was chosen to be used for the welding job. For instance, welding aluminum or chromium-based materials is tough to weld due to their layers of oxides. 

This causes problems during the welding process as it could take up to two hours to ensure that a steel rod can penetrate into the metal and make a smooth weld. 

With this type of material, if there is any oxidization on your metal, you risk melting your workpiece entirely.

However, with this problem, you can use a flux-cored welder. 

These rods are coated in a particular type of clay that protects the steel rod from oxidization and penetrates the aluminum or other metal much more effortlessly. 

With this type of welding, you will find that your entire project goes much smoother, and you will be able to save time in your welding process.

With arc welding, there are two types of rods that are used. 

The first rod is called an electrode, held by a clamp and placed loosely inside the welding machine, while the other rod is called a filler rod, inserted tightly inside the machine to complete your weld correctly.

Summary

As a skill used in various situations, arc welding is something that many people may have little knowledge about despite a large number of industries and uses. 

Arc welding is a type of welding that creates an electrical arc between a source of energy and the welding rod to start the welding process. 

These arcs are what help to melt the metal that’s being used to create the weld.

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