This paper presents a theoretical study on direct drive rotary friction welding process and investigates the possibility of producing an analytical solution of the heat transfer equation, both during the first part of heating process and the second part of the process when the operative temperature of the material at the end of the rod is assumed to be constant and equal to plasticization temperature. The solutions of the set of equations obtained have been compared with some experimental data present in literature [ 9 ] showing a fair agreement The burn-off volume (length in the case of a cylinder) can be estimated. The proposed method is simple, suitable for engineering calculations and can be used to predict the thermal evolution of welded elements and the burn-off volume, to reduce setup difficulties and to realize a more effective control on the process. Direct drive rotary friction welding has an increasing importance in manufacturing because it produces a solid junction between different material and alloys, even heterogeneous material which cannot be joined using common welding processes.The paper focuses on frictional heat generation and aims to describe the heat transfer model during the process, starting from the classical theory of friction. The heating phase is described as a function of four characteristic physical variables: axial force, spin velocity, torque and time. These parameters are fundamental to predict heating of the welded rods and the burn-off volume and can be easily controlled during the industrial process. The consequent heat transfer equation is solved analytically and the results are compared with experimental data present in literature. It is shownThe proposed method can be useful for different uses: to predict the thermal evolution of welded elements and burn-off volume, to reduce setup difficulties and to realize a more effective control on the process.