Investigation of material flow during friction extrusion process

• An understanding of the friction extrusion process is provided.
• Material flow features in friction extrusion are predicted using CFD simulations.
• Simulation predictions for a modified process have been verified analytically.
• Simulation predictions for a modified process have been validated experimentally.
• Simulation results are useful for interpreting experimental observations.

Material flow during a friction extrusion process is investigated. A three-dimensional computational fluid dynamics (CFD) model of the friction extrusion process is proposed with a no-slip contact condition between the rotating tool and the material being processed. In the CFD model, the material considered is aluminum alloy 6061. During processing the material is treated as a non-Newtonian fluid with a viscosity that is temperature and strain rate dependent. As a first model of this process, the focus of the CFD model is to provide initial insights about the material flow field, which can be used to help with the design and interpretation of experiments to measure the flow field. Due to the lack of experimental validation data at this stage, and to provide an understanding of the accuracy and validity of CFD simulation predictions of the velocity field, the same process but with a model fluid and without extrusion is considered. This modified process has been studied analytically, numerically, and experimentally, and CFD simulation predictions have been verified analytically and validated experimentally. Then the full process with consideration of extrusion is modeled using CFD and simulation predictions of the flow field are presented.