What is Welding? – Definition, and Types

What is Welding?

Welding is a fabrication process whereby two or more parts are fused together by means of heat, pressure, or both forming a join as the parts cool. Welding is usually used on metals and thermoplastics but can also be used on wood. The completed welded joint may be referred to as a weldment.

Welding is distinct from lower temperature metal-joining techniques such as brazing and soldering, which do not melt the base metal.

In addition to melting the base metal, filler material is usually added to the joint to create a weld pool (pool of molten material) that cools to form a joint based on the weld configuration (butt, full penetration, fillet, etc.), can be stronger than the base material (parent metal).

Pressure can also be used in conjunction with heat or alone to create a weld. Welding also requires some form of shield to protect the filler metals or molten metals from contamination or oxidation.

Some materials require the use of specific procedures and techniques. A number is considered “non-weldable,” a term that does not normally appear in dictionaries but is useful and descriptive in engineering.

The parts that are joined are called the parent material. The material that is added to form the joint is called the filler, or consumable. In the form of these materials, they may be called a base plate or tube, filler wire, consumable electrode (for arc welding), etc.

Consumables are usually chosen so that they have a similar composition to the parent material and thus form a homogeneous weld. However, there are cases, for example when welding brittle cast iron, when a filler with a very different composition and therefore properties is used. These welds are called heterogeneous.

Many different energy sources can be used for welding, including a gas flame (chemical), an electric arc (electric), a laser, an electron beam, friction, and ultrasound.

Although it is often an industrial process, welding can be done in many different environments, including outdoors, underwater, and outer space. Welding is a hazardous endeavor and precautions must be taken to avoid burns, electric shock, damage to eyesight, inhalation of toxic gases and fumes, and exposure to intense ultraviolet radiation.

Definition of welding

Welding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion. Welding is distinct from lower temperature metal-joining techniques such as brazing and soldering, which do not melt the base metal.

Welding

How Does Welding Work?

Welding works by joining two materials together without a separate binder material. Unlike brazing and soldering, which use a binder that has a lower melting point, welding joins the two workpieces directly together. Understanding this difference is key to understanding welding and why it is preferred for permanent, long-lasting construction.

The basic purpose of welding is to join two elements with a permanent joint. Welders usually work with metal or thermoplastic and use permanent filler material to bond them together. Welding is used to creating many modern constructions in our world, such as skyscrapers, cars, ships, and planes.

In the past, builders used other methods of joining metal workpieces. Soldering, brazing and riveting are alternatives to welding.

How to weld Plastics?

Plastics welding also uses heat to join the materials (although not in the case of solvent welding) and is accomplished in three stages.

Firstly, the surfaces are prepared before the application of heat and pressure, finally, the materials are allowed to cool to create fusion. Joining methods for plastics can be divided into external or internal heating methods, depending on the exact procedure.

How to weld Wood?

In wood welding, the heat generated by friction is used to bond the materials together. The materials to be joined are subjected to high pressure before a linear frictional movement generates heat to join the workpieces together.

This is a quick process that allows the wood to be joined without glue or nails in a matter of seconds.

Types of Welding

There are different types of welding:

  • MIG or Gas Metal Arc Welding (GMAW),
  • TIG or Gas Tungsten Arc Welding (GTAW),
  • Stick or Shielded Metal Arc Welding (SMAW)
  • Flux-cored – Flux-cored Arc Welding (FCAW).
  • Metal Active Gas (MAG) Welding,
  • Submerged arc welding (SAW),
  • Plasma arc welding.
  • Energy Beam Welding (EBW)

Let’s dive deeper into each type of welding,

1. Mig or Gas Metal Arc Welding (GMAW)

MIG welding is used in the automotive industry to repair vehicle exhaust fumes and also in the manufacture of houses and buildings. It is one of the most common types of welding. This is a type of arc welding that uses a continuous wire called an electrode. You also use a shielding gas that flows through the welding gun and protects it from contamination.

2. Tig or Gas Tungsten Arc Welding (GTAW)

TIG welding also uses electric arc like MIG. For TIG welding you use an electrode made of tungsten. Tungsten is one of the hardest metal materials. It won’t dissolve or burn. Welding can be done by a process known as melting, which may or may not use a filler metal. TIG also uses an external gas supply such as argon or helium.

TIG welding is also used in the aerospace and automotive industries, as well as in other industrial markets. This is also a great way of welding for Iowa as it can be very useful for farmers to weld cart frames, fenders, and other vital equipment.

3. Stick–Shielded Metal Arc Welding (SMAW)

A great advantage of Stick welding is that it is portable. Stick welding is used in construction, maintenance and repair, underwater pipelines, and industrial manufacturing. For this type of welding, you use shielded metal art welding, more commonly known as stick welding.

You are using a consumable and protected electrode or stick. The stick softens and connects metals by heating with an arc between a coated metal electrode and the base metal workpiece. When the stick melts, its protective shell also melts, protecting the sweat area from oxygen and other gases that may be in the air.

4. Flux-Cored – Flux-Cored Arc Welding (FCAW)

Flux-cored arc welding is similar to MIG welding in that both continuous wire and power supplies are used. You will combine a continuous electrode with a base metal. The electrode is a hollow tube filled with flux passed through the welding gun into the weld pool.

When welding outdoors, a flux shield offers protection from the weather elements. This type of welding is used for welding thicker metals and is used in the machining industry.

5. Metal Active Gas (MAG) welding

Metal Inert Gas (MIG) and Metal Active Gas (MAG) welding are gas metal arc welding (GMAW) processes that use heat created from a DC electric arc between a consumable metal electrode and a workpiece that melts together to create a weld pool that fuses to form a join.

6. Submerged-arc welding (SAW)

Submerged-arc welding (SAW) is a common arc welding process that involves the formation of an arc between a continuously fed electrode and the workpiece. A blanket of powdered flux generates a protective gas shield and a slag (and may also be used to add alloying elements to the weld pool) which protects the weld zone.

7. Plasma Arc Welding

Plasma arc welding is a precision technique and is commonly used in aerospace applications where the metal thickness is 0.015 of an inch. One example of such an application would be on an engine blade or an air seal. Plasma arc welding is very similar in technique to TIG welding, but the electrode is recessed and the ionizing gases inside the arc are used to create heat.

8. Electron Beam and Laser Welding

Laser welding is the latest innovation in welding technology. This technique is currently only used in large industrial applications. Laser welders use a high-energy beam to fuse materials. It is an expensive system that requires expert control and sensitivity.

Different Types of Welding Joint

There are 5 main joints used in welding. These are:

  • Butt joint: A joint between the ends or edges of two parts making an angle to one another of 135-180° inclusive in the region of the joint.
  • Corner joint: A Joint between the ends or edges of two parts making an angle to one another of more than 30 but less than 135° in the region of the joint.
  • Edge joint: A Joint between the edges of two parts making an angle to one another of 0 to 30° inclusive in the region of the joint.
  • Lap joint: A Joint between two overlapping parts making an angle to one another of 0-5° inclusive in the region of the weld or welds.
  • Tee joint: A Joint between the end or edge of one part and the face of the other part, the parts making an angle to one another of more than 5 up to and including 90° in the region of the joint.
  • Cruciform Joint: A Joint in which two flat plates or two bars are welded to another flat plate at right angles and on the same axis.

Read detailed article: Different Types of Welding joint

Types Of Welds

Following are the Different Types of Welds:

  • Fillet Welds
  • Groove Welds
  • Surfacing Weld
  • Plug Weld
  • Slot Weld
  • Flash Weld
  • Seam Weld
  • SpotWeld
  • Upset Weld

1. Fillet Welds

A fillet weld joins two surfaces at an approximate right angle to each other. There are several types of fillet weld:

  • Full fillet weld is a weld where the size of the weld is the same as the thickness of the thinner object joined together.
  • Staggered intermittent fillet weld refers to two lines of intermittent welding on a joint. An example is a tee joint (see below) where the fillet increments that are in one line are staggered in comparison to the other line.
  • Chain Intermittent fillet weld refers to two lines of intermittent fillet welds in a lap joint or T where the welds in one line are approximately opposite those in the other line.

Other terms associated with fillet welds include:

  • Boxing: which refers to the continuation of a fillet weld around a corner of a member. It is an extension of the principal weld.
  • Convexity: Refers to the maximum perpendicular distance from the face of a convex fillet weld to a line joining the toes.

2. Groove Welds

The second most popular type of weld is the groove weld. There are seven basic types of groove welds, which are shown in figure 6-25.

The groove weld refers to beads that are deposited in a groove between two members to be joined. The type of weld used will determine the manner in which the seam, joint, or surface is prepared.

3. Surfacing Welds

These are welds composed of one or more strings or weave beads deposited on an unbroken surface to obtain desired properties or dimensions.

This type of weld is used to build up surfaces or replace metal on worn surfaces. It is also used with square butt joints.

4. Plug Weld

Plug welds are circular welds made through one member of a lap or tee joint joining that member to the other.

The weld may or may not be made through a hole in the first member; if a hole is used, the walls may or may not be parallel and the hole may be partially or completely filled with weld metal. Such welds are often used in place of rivets.

Note: A fillet welded hole or a spot weld does not conform to this definition.

5. Slot Weld

This is a weld made in an elongated hole in one member of a lap or tee joint, joining that member to the surface of the other member that is exposed through the hole. This hole may be open at one end and maybe partially or filled with weld metal.

Note: A fillet welded slot does not conform to this definition.

6. Flash Weld

Flash welding is referred to as a resistance welding process where fusion is produced over the entire abutting surface.

Heat is created by the resistance to the current flow between two surfaces and by the application of pressure after heating is mostly complete. Flashing is accompanied by the expulsion of metal from the joint.

7. Seam Weld

A weld made by arc seam or resistance seam welding where the welding process is not specified. This term infers resistance seam welding.

8. Spot Weld

A spot weld is a weld made by arc spot or resistance spot welding where the welding process is not specified. This term infers a resistance spot weld.

9. Upset Weld

An upset weld is a resistance welding process where fusion occurs progressively along a joint of over the entire abutting surface.

The application of pressure before heating is required and occurs during the heating period. Heat comes from the resistance to the flow of electric current in the area of contact between the surfaces.

What Is a Welding Position?

A welding position is a technique that allows a welder to join metals in the position in which they are found or the position in which a specific component will be used. Often that may be on the ceiling, in the corner, or on the floor.

Techniques have been developed to allow welding in any position. Some welding processes have all-position capabilities, while others may be used in only one or two positions.

All welding can be classified according to the position of the workpiece or the position of the welded joint on the plates or the sections being welded.

Why Are There Different Welding Positions?

Those who’ve never taken welding classes or fused metal in the field might assume a welder simply sits at a workstation and fuses the metal components in front of them, moving freely around the table and repositioning the workpiece as needed.

But in everyday work environments, joining metal can be much trickier. Workpieces may be attached to the ceiling, the corner or the floor.

Welders need techniques to be able to weld in any position. So the four common welding positions were developed.

Different Welding Positions

There are four main types of welding positions as per American Welding Society(AWS):

  • Flat position
  • Horizontal position
  • Verticle position
  • Overhead position

1. Flat position (1G Or 1F)

Also referred to as a “down hand” position, the flat position weld is the easiest and often the first weld that new students learn. The metals to be joined are placed flat, and the welder passes the electric arc over them, moving across the workpiece in a horizontal direction. The joint’s top side is welded together allowing the molten material to move downward into its edges or groove.

Note: The axis of a weld is a line through the length of the weld, perpendicular to the cross-section at its center of gravity.

2. Horizontal Position (2F Or 2G)

The horizontal position is considered an out-of-position weld. Along with the vertical and overhead, the horizontal position can be more challenging to perform and require a higher level of skill.

The weld axis is horizontal. How the position is executed depends on the type of weld. For a fillet weld, the weld bead is placed where a vertical and a horizontal piece of metal meet at a 90-degree angle. When performing a groove weld, the weld face will be along a vertical plane.

3. Vertical Position (3F Or 3G)

For a vertical position weld, both the weld and plate will lie vertically. One of the major problems when performing this weld is the molten metal flowing downward and piling up. Welding in a downhill or upward vertical position can prevent this issue.

The flow of metal can be controlled by pointing the flame upward at a 45 degree angle to the plate, and holding the rod between the flame and the molten puddle (see above).

The manipulation of the torch and the filler rod keeps the metal from sagging or falling and ensures good penetration and fusion at the joint.

Both the torch and the welding rod should be oscillated to deposit a uniform bead. The welding rod should be held slightly above the centerline of the joint, and the welding flame should sweep the molten metal across the joint to distribute it evenly.

4. Overhead Position (4F Or 4G)

The overhead position weld is the most difficult position to work in. The welding will be performed with the two pieces of metal above the welder, and the welder will have to angle him or herself and the equipment to reach the joints.

One major issue can be the metal sagging from the plate. When the metal sags, it creates a crown. To avoid this issue, the puddle of molten metal should be kept small.

As you can see, the welding position is essentially the location of the welder in relation to the workpiece. One of the major considerations with each position is the direction the welding consumable will flow due to gravity.

The position of the welded joint on the plates or sections to be joined forms the basis for all welding classifications, which are represented by welding symbols.

Before we discuss the different welding classifications, it may help you to first understand the types of welds and weld joints on which these positions are typically performed.

Parts of Welding(Features of Completed Welds)

  • Machine: Welding machine is the main parts of this process, because without machine certainly, we can not do welding process.
  • Electrode Cable: The function Electrode cable connects the current from welding machine to electrode which we use to weld the base metal.
  • Massa Cable: Massa Cable has a function for connecting current from machine to base metal, after that base metal and electrode touch then will welding process is happening.
  • Welding Power Source: Have to function for supply current from electrical source to welding machine.
  • Current Control: For control current output which uses for the welding process, big or little the current dependent form type or thickness of material (base metal).
  • Electrode Holder: For hold the electrode so we can do welding process easily. Otherside holder too has a function for an electric current to the electrodes.
  • Earth Cramp: To connect the machine to the base metal.
  • Switch:For on or off the welding machine.
  • Electrode: As a filler metal, after the welding process finish then the electrode will change be weld metal. The electrode has a flux which the function is to protect steel melting when the welding process takes place.
  • Parent Metal: Metal to be joined or surfaced by welding, braze welding or brazing.
  • Filler Metal: Metal added during welding, braze welding, brazing or surfacing.
  • Heat Affected Zone (HAZ): The part of the parent metal metallurgically affected by the weld or thermal cutting heat, but not melted.
  • Fusion Line: Boundary between the weld metal and the HAZ in a fusion weld. This is a non-standard term for weld junction.
  • Weld Zone: Zone containing the weld metal and the HAZ.
  • Weld Face: The surface of a fusion weld exposed on the side from which the weld has been made.
  • Weld Root: Zone on the side of the first run furthest from the welder.
  • Weld Toe: Boundary between a weld face and the parent metal or between runs. This is a very important feature of a weld since toes are points of high-stress concentration and often they are initiation points for different types of cracks

FAQs.

What is Welding?

Welding is a fabrication process whereby two or more parts are fused together by means of heat, pressure, or both forming a join as the parts cool. Welding is usually used on metals and thermoplastics but can also be used on wood. The completed welded joint may be referred to as a weldment.

What are the types of Welding?

There are four main types of welding. MIG – Gas Metal Arc Welding (GMAW), TIG – Gas Tungsten Arc Welding (GTAW), Stick – Shielded Metal Arc Welding (SMAW), and Flux-cored – Flux-cored Arc Welding (FCAW). We dive deeper into each type of welding here.

What are the Types of Welds?

Different Types of Welds:
1. Fillet Welds
2. Groove Welds
3. Surfacing Weld
4. Plug Weld
5. Slot Weld
6. Flash Weld
7. Seam Weld
8. SpotWeld

What are Welding Positions?

There are four main types of welding positions:
1. Flat position
2. Horizontal position
3. Vertical position
4. Overhead position

How does Welder Work?

Welding works by joining two materials together without a separate binder material. Unlike brazing and soldering, which use a binder that has a lower melting point, welding joins the two workpieces directly together.

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