What is friction welding?

What is friction welding?

Friction welding is a solid-state joining process. It welds two workpieces by heat produced due to the rotational motion of one part over the other stationery part with axial compression force. Friction between two-part surfaces is responsible for generating heat with axial force. Once the plastic forming temperature is achieved, the rotating part is uniformly forced towards the stationery part till it forms a permanent joint. No external heat requires to do this kind of welding. It is a new technology.

Overview of friction welding.

Welding is the process of joining two metallic & nonmetallic parts with each other. Depending on the type of application welding method is decided. Now friction welding technology is using in various fields due to its advantages. It is based on the principle of friction. How heat is producing due to friction between two parts utilized to join two metals with each other. Let’s discuss this in more detail.

Basics behind friction welding.

If you rub your both the hand with each other, then your palms become warmer. If further you increased pressure and rub more, then it becomes hotter. It happens because we have roughness on our hands. Due to this roughness, friction causes, and this friction leads to generate heat. The same principle is using in the friction welding process. 

Now the question that arises is what is roughness (asperity) & friction?

What is asperity?

No surface is perfectly flat in the world. If we see the surface on the microscope, we can see the unevenness or roughness on the surface. It is called asperity. When two surfaces with asperities get rubbed with each other by applying force, it causes friction in between them. This friction leads to generate heat.

What is friction?

Friction is the resistance to the sliding or rolling action of one object towards other due to asperity present on their surfaces and the force applied.

Friction welding uses the same phenomenon of asperity and friction to join two parts.

Types of friction welding.

As per the type of application, it is dividing into different types. Let’s have a look.

Rotatory friction welding

In the rotary friction welding process, one rotating surface is forced over another stationary surface. In this process, axial compression force is applied over others with high rotating force. It causes high heat between two surfaces. Due to this, plastic deformation causes fix bond between them.  

Linear friction welding

In linear friction welding, two surfaces of the welding part oscillate over each other with high reciprocating motion & high compressive force. It causes high heat generation between two surfaces. 

Friction stir welding

Friction stir welding is using for joining two different plates in between their thickness. The tool is made in such a way that, a pin is profiled on the bottom of the cylindrical shoulder. This pin is using for welding. In this welding process, the probe is projected in between the seam of the two plates until the shoulder rests on them. Once the shoulder rests, it starts rotating with high speed and compressive force. It causes heat due to friction between two surfaces and metal getting soften. The probe below the shoulder moves in a linear direction between the seam and forms a bond between the two surfaces.

Friction stir spot welding

This welding process is used for welding two plates on each other.

Friction stir spot welding is similar to friction stir welding. But the major difference is that tool is not moved in the linear direction. Instead of that, the tool rotates at high speed and force in one spot. It causes high heat in between two plates. Depending on the material & magnitude of the heat, welds forms in the two plate. 

What is inertia welding?

Many peoples think that inertia welding is the same as friction welding. But it is a type of friction welding. It is the same as rotary friction welding. It is called inertia because it uses a flywheel to store energy to rotate. 

In this process, the rotating surface is clamped in the spindle. This rotating surface is forced over other stationery part surfaces with high rotating speed and compressive force. Depending on the type of metal, rpm is set. Due to that, it generates high temperatures. 

Once the speed reaches this level, the drive disconnects, and it rotates due to energy stored in the flywheel. The concept of storing energy is most common in Mechanical Engineering works.

Advantages of friction welding

  • It is environmentally friendly because of the non-formation of smoke, gases.
  • No external medium like gas, filler metal, and flux is required.
  • In this process, two different metals can be able to join.
  • Strength in between weld is strong.
  • It takes less time for this process.
  • Various types of metal can be weld by using it.

Disadvantages of friction welding

  • Set up cost is so expensive.
  • It is not suitable for big parts.


  • This process mostly using in the aerospace, marine, and oil industries.
  • In electrical parts manufacturing industries. It is using for joining copper and aluminum parts.
  • In automobile industries, this process is using for various applications. Ex. For joining engine valves.
What is meant by friction welding?

Friction welding is a solid-state joining process. It welds two objects by heat produced due to the rotational motion of one part over the other stationery part with axial compressive force.

FWT is a leading company in this field.

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