Hello, guys welcome to all today we will discuss the most important topic that is Welding, in this topic, we will know What is welding process and how many types of welding.
Welding is the art of Joining the materials.
It is a type of fabrication process which joins the materials, normally metals or thermoplastics.
Welding should always be done by experienced and skilled welders, failing which the chances of welding defects increases.
In this topic, we will study the different types of welding in production work.
So friends let's know What is welding process and how many types of welding.
What is Welding Process?
In the welding process, the joining of material like metal or thermoplastic pieces is done by increasing their temperature to the range of its fusion temperature so that, they form a pool of molten metal and after then cool to form the strongest joint.
The welding process provides permanent joint & its joining strength is much better than compared to Soldering and Brazing.
Types of Welding
Welding can be divided into the following basis:
- On the basis of the materials to be welded
- On the basis of the pressure applied for welding
On the basis of the materials to be welded
On the basis of the materials to be welded, welding can be further divided into two types:
- Homogeneous Welding
- Heterogeneous Welding
Homogeneous Welding
In this joining process, two similar metal parts are jointed either by using a filler rod and no pressure is applied during the welding process.
Eg, welding of mild steel part.
Heterogeneous Welding
In this joining process, two dissimilar metal parts are joined by using the filler metal.
The filler metal is soluble in both the parent metal.
The filler metal is less than that of metal parts to be joined such that Its melting point is less than the parent metals.
On the basis of the pressure applied for welding
On the basis of the pressure applied for welding, types of welding are:
- Pressure or Plastic Welding
- Non-pressure or Fusion Welding
Pressure or Plastic Welding
In this welding process, the surfaces which are to be welded is firstly heated up to their molten stage and then they are joined by applying pressure.
Non-pressure or Fusion Welding
In this process, the surfaces which are to be welded are kept together and heated by a heating source (such as flame or electric arc), till they reach the molten stage. In addition to this, a filler metal is used.
I think from the above definition you all well understand what is welding process?
Now from the table we easily understand how many types of welding use Pressure and Non Pressure Welding.
Types of Pressure and Non Pressure Welding
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| Types of Pressure and Non Pressure welding |
Brief Description of Welding Processes
From the above Types of welding, some welding processes are given below:
- Arc Welding
- Gas Welding
- Solid State Welding
- Resistance Welding
- Thermit Welding
- Electron Beam Welding (EBW)
Arc Welding
Arc welding is a welding process in which fusion occurs by heating with an electric arc.
Most often, arc welding is performed without pressure.
There are the following types of arc welding:
- Manual Metallic Arc Welding
- Submerged Arc Welding
- Tungsten Inert Gas (TIG) Welding
- Metal Inert Gas (MIG) Arc Welding
- Plasma Arc Welding (PAW)
- Atomic Hydrogen Welding (AHW)
- Carbon Arc Welding (CAW)
Manual Metallic Arc Welding
When the welding is done by hand with flux coated electrode, then the welding is known as manual metallic arc welding.
Its other name is shield metal arc welding.
Submerged Arc Welding
It is one of the arc welding processes where coalescences(fusion) is produced by heating and an electric arc is set up between the bare electrode (copper coated) and workpiece under a blanket of granular flux metal electrode, continuously feed and act as a filler metal.
Tungsten Inert Gas (TIG) Welding
The Tungsten Inert Gas welding process is also called gas tungsten arc welding.
It is also one of the types of arc welding process that uses a non-consumable tungsten electrode to produce the welding process and join the metal.
In this process during welding weld area is saved from atmospheric contamination by an inert shielding gas like argon or helium.
Metal Inert Gas (MIG) Arc Welding
Metal inert gas welding is another name is metal gas arc welding.
The metal inert gas welding process is a type of tungsten inert gas welding process.
This process is used where more precision is required and the consumable electrode is used in this process.
In this welding process, the electric arc forms between the wire electrode and workpiece which heats the workpiece, causing them to melt and join after solidification.
Plasma Arc Welding (PAW)
Plasma arc welding is an arc welding process and plasma refers to an ionised state of matter.
In PAW, the electrode is located within the body of the torch and separated by an envelope of shielding gas.
Atomic Hydrogen Welding (AHW)
Atomic hydrogen welding is also a type of arc welding process that uses an arc between the two metals.
Carbon Arc Welding (CAW)
Carbon arc welding is a type of welding process, which produces heat by joining the metal.
In this process, carbon (graphite) electrodes are used.
Electro Slag Welding (ESW)
Electro slag welding is a highly productive type of welding process.
This process is generally used for welding a thick material only in a vertical or nearest to a vertical position.
Gas Welding
Gas welding is a process of melting and joining metal parts by means of a gas flame.
In gas welding, three types of gas welding flames are used neutral, carburizing, and oxidizing flame.
There are the following types of gas welding given below:
- High Pressure Gas Welding
- Low-Pressure Gas Welding
High Pressure Gas Welding
High pressure welding consists of the pressure of acetylene gas which means 15 kg per square centimetre.
It is performed in industries. This process of welding is known as high pressure gas welding.
Low Pressure Gas Welding
This process consists of a pressure of acetylene gas that means, 1 kg per square centimetre generated by a small gas generator in a domestic environment.
This process of welding is known as low pressure gas welding.
Solid State Welding
Solid state welding is one of the important types of the welding process, in which the heat required for welding purposes is produced by rubbing or by applying hammering operation on two workpieces.
In the solid state, welding, pressure is applied to form the weld joint.
A solid state of welding can be divided into the following categories:
- Forge Welding
- Friction Welding
- Ultrasonic Welding
- Laser Beam Welding (LBW)
Forge Welding
Forge welding is a type of solid state welding process in which the metal parts are joined when heated the metal parts up to metal's hot working temperature and then forged together by using the hammer or other.
This welding process is specially applied in a Forging Process.
Friction Welding
Friction welding is also a type of solid state welding process in which heat is produced through frictional heat combined with pressure.
In this process, heat is generated through the friction between the two metals or metal parts surfaces, normally by rotating one part relative to the other.
Ultrasonic Welding
In ultrasonic welding, high frequency ultrasonic acoustic vibrations are used to weld the workpieces.
It is used to weld the two dissimilar metals such as aluminium to steel, aluminium to tungsten, nickel to brass, etc.
Laser Beam Welding (LBW)
Laser beam welding is a welding technique used to join multiple metal parts using a laser beam.
The beam provides a concentrated source of heat, allowing narrow and deep welds to be made at high welding speeds.
This process is often used in large volumes, for example in the automotive industry.
Resistance Welding
Resistance welding is a type of pressure welding process.
The basic working principle of resistance welding depends upon
H = I^2RT
where,
H = heat generated
T = time
R = resistance
I = current required
Thermit Welding
Thermit welding is a welding process in which no external heat source is required for melting the workpiece to form the joint.
Electron Beam Welding (EBW)
Electron beam welding is a type of fusion welding process, in which a high velocity beam electron is applied as a force to join the two materials like similar or dissimilar metal forming a joint on solidification.
Welding Joint
The various types of joint prepared during the welding process are as follows:
- Butt Joint
- Lap Joint
- T Joint
- Edge Joint
- Corner Joint
Butt Joint
In the butt joint, two members are joined by simple butting them together.
Single side welding is done up to the thickness of 3mm, for the thickness of 3 to 5 mm welding is done on both sides of the workpiece.
Lap Joint
When the joint is formed by overlapping the two surfaces, then it is known as a lap joint.
T Joint
When one plate is joined at an angle of 90° to the other plate, then the joint is known as the T joint.
Edge Joint
This joint is like a butt joint. The joint is made by hanging the edges of their sheets.
Corner Joint
When the edge of the sheets are held together and jointed, then this type of joint is known as a corner joint.
Welding Defects
Welding defects are of two types, which are given the following:
- External Defect
- Internal Defect
External Defect
1. Cracks
2. Uneven bead
3. Spatters
4. Craters
5. Undercut
6. Distorted joints
7. Surface porosity
8. Lack of filler metal
9. Over heating
10. Excess of penetration
Internal Defects
1. Blow holes or porosity
2. Internal cracks
3. Slag inclusion
4. Lack of fusion
5. Incomplete penetration
6. Harder and brittle joints
So, I hope you all clearly understand What is welding Process and how many types of welding.
If any queries you are free to all comment in a comment box.
Thank You
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