FSW Power

Arc welding procedures define the welding travel speed and the level of the welding power in terms of current and voltage. In a similar manner, the travel speed of a Friction Stir Weld will be a variable defined within the associated welding procedure. However, a FSW procedure does not define the welding power. Instead, the FSW conditions are defined by adopting a combination of the linear and rotation speeds of the tool. The power required to make a weld is the result of the torque needed to turn the tool at the chosen rotation speed. These notes provide a simplified set of equations for the prediction of the power needed to make a Friction Stir Weld. The final equation is easy to use and has a wide range of applicability.

A simple assessment of FSW

The primary parameters of FSW weld procedure are the tool linear and rotation speeds. Therefore, unlike many other welding processes, the power needed to make a weld is not an explicit component of a FSW weld procedure. Clearly, the torque and force needed for FSWs are important because they can help to show whether the tool and the FSW machine have the capacity to make the weld or welds of interest. A trial weld could be made, but this may be dangerous if it is close to the extremes of the mechanics of the set up. Alternatively, it advanced modelling software such as Computational Fluid Dynamics (CFD) would be capable of predicting the welding conditions. The current page describes how it is possible to make a prediction of the power needed to make a weld (together with the associated torque) using a simple equation that can easily be evaluated in a spreadsheet.

The equation is derived below. The four components of the derivation are listed below.

• The temperature of the material at the tool. This should be expressed in the following form {{x2|<math>T = T \left( T, v, x \right)</math>}}

<math>E=mc^2</math>

\[T = x + z\]