Friction welding and friction spot welding are thermal joining processes. The heat is generated due to friction between the components that should be joined and/or additional tools. The specialty of all friction welding processes is that the joining takes place below the melting temperature of the components. The joint is formed by heating up the materials until they are in a dough-like state. Due to applied pressure a type of upsetting takes place, which forms the weld seam and the weld joint.
Friction welding is a process type that is suited for joining massive parts like shafts or axles. Whereas friction spot welding is a process type that is suited for joining sheet metal parts. It can be used for steel-steel combinations as well as aluminum-stell combinations.
Friction welding and friction spot welding processes can be modeled in two different ways with Simufact Forming. Either as a 3D model or as a 2D axisymmetric model.
When using a 3D model, the friction heat is directly determined from the friction forces that occur due to the friction coefficient and friction model defined by the user. The major disadvantages of this approach are:
- Long computation times
- Critical meshing issues
Furthermore, the coulomb or shear friction may not be suitable for this special friction conditions. Moreover, unrealistic high friction coefficients are necessary to generate sufficient heat compared to a real process.
Better suited is the approach of modeling the process as a 2D axisymmetric process. This approach uses a heat source based on an analytical equation, which then sets the temperature as a boundary condition. User input for the heat source is the rotational/translational velocity and the friction coefficient, which can be defined as a temperature dependent table. The heat source approach is available for 3D and 2D (planar and axisymmetric) processes. Advantages of 2D modeling are:
- Short computation times (few hours/minutes)
- Simple meshing
- Independent definition and investigation of friction parameters influencing heat generation and material flow.
The Pressure Welding application module can generate a 3D model of the virtual joint for different load cases (e.g. lap shear, coach peel, cross tension) with only a few clicks. User-defined result variables can help to define your failure criterion and to investigate the strength of your joint until failure occurs.