# Calculation of torque in friction welding

• robkm
In summary, friction welding does not melt the materials, and requires less energy than traditional welding.
robkm
Hi all.
As part of a Uni project I need to calculate the torque required to rotate one pipe relative to another stationary pipe so the two ends of the pipes are in contact with each other and therefore the rotation and the axial force of the rotation pipe causes friction and melt.

I know at first, when there is no melt and the surfaces are dry, the friction force F is
F=N*μ and therefore Torque, T= ∫ Nμdr (with boundary conditions of r inner and r outer (sorry, not sure how to put them on in equ))

But what I am unsure about is how to calculate Torque when friction has caused the pipes to melt and therefore I am guessing the torque is dependent on the melt.

Any ideas would be greatly appreciated.

#### Attachment is pic of configuration of pipes ####

#### Attachments

• friction welding diagram.doc
23.5 KB · Views: 659
Assuming that the interface actually melts all the way across at the same time (I think this is what is supposed to happen in this operation, isn't it), then it would seem reasonable to model this as a viscous friction, a distributed force proportional to the relative velocity across the interface. With that assumption, I think you have a basis for making a calculation. Whether or not it is a really good model is another matter altogether!

Friction welding does not melt the materials since the temperature is controlled and kept below the melting temperature. It maintains a solid phase during the heat and pressure sequence, which underlay the principles of forging. It is true that the materials will soften (plasticize) at the faying surface and experience some extrusion.

A crude estimate of the required energy for friction welding:
- Identify coefficient for dynamic friction between the two materials.
- Identify coefficient of thermal conductivity of materials.
- Require that (say) 1 mm thickness of each material at faying surface must reach melting temperature (this is upper bound).
- Write energy balance equation.

.. Solve.

## 1. What is torque in friction welding?

Torque in friction welding refers to the turning or rotational force applied to the materials being joined together. It is a critical parameter in the welding process as it affects the strength and quality of the resulting weld joint.

## 2. How is torque calculated in friction welding?

Torque in friction welding is calculated by measuring the rotational speed of the materials being welded and the applied axial load or force. The torque can then be calculated by multiplying the rotational speed by the axial load.

## 3. What factors affect the calculation of torque in friction welding?

The calculation of torque in friction welding is affected by several factors, including the material properties of the materials being welded, the rotational speed, the applied axial load, and the type of friction welding process being used.

## 4. What is the significance of torque in friction welding?

Torque is a crucial parameter in friction welding as it directly affects the amount of heat generated during the welding process. The amount of torque applied can also impact the microstructure and mechanical properties of the resulting weld joint.

## 5. How can torque be controlled in friction welding?

Torque in friction welding can be controlled by adjusting the rotational speed and the applied axial load. Additionally, using a pre-determined torque value and closely monitoring the welding process can help ensure consistent and high-quality weld joints.

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