An Experimental Study on Interference Friction Welding Process

. Friction welding is a solid state joining process in which the frictional heat and plastic deformation due to lateral force contributes to diffusion bond formed between the two workpieces in relative motion while in contact. There are several advantages that can be attributed to the friction welding processes including faster joining rates, lower heat affected zones, and refinement of material at the weld interference because of plastic deformation. Interference friction welding process is a variant of friction welding processes that has been proposed to be used to join a tube/round bar to a sheet metal/plate. The name interference friction welding refers to the fact that an interference is created between a rotating tube and the walls of the drilled hole of a stationary plate. The rotating tube is made to pass through the drilled hole of smaller diameter and hence the interference causes the plastic deformation and frictional heat due to sliding contact in axial direction (due to tube feed) and tangential direction (due to tube rotation). In the experimental investigation, the effect of different process parameters such as feed rate, spindle speed, amount of interference, and penetration depth of the tube on the axial thrust force and the torque generated at the weld interface was studied. The change in torque and thrust force values were related to the amount of heat generation and plastic deformation at the interface that contributes to the quality of the solid state weld joint being formed. The quality of the weld joints formed at different parameters were evaluated from the microscopic analysis and shear testing. The maximum joint strength observed was 62 MPa which was 33 % of the yield strength of the Al 6061 material. Moreover, the joint strengths were compared with the interference fit joints that were formed from the shrink fitting operation. The shear strength of the shrink joint was obtained to be 10.89 MPa. In addition, an analytical model has been proposed based on the existing literature on friction welding processes. It is shown that the model can accurately predict the thrust force and torque values during the interference friction welding process for the given experimental parameters