Numerical simulations are applied to investigate the simultaneous radial-forward extrusion process in a combined extrusion such as subsequent radial-forward extrusion after radial extrusion. Design factors for the process such as gap height, deflection angle into annular gap and frictional condition are employed in the analysis. The analysis is focused to see the influence of design factors on the maximum force requirement for the forming process. One of the selected simulation results is compared with the experiments in terms of load-stroke relationships. The pressure distributions exerted on the die-wall interfaces are also investigated to reveal if the tooling system is safe, especially the die set. The plastic stress-strain relationship is derived analytically from the material constants used in elastic deformation analysis. It is revealed from the simulation results that the influence of the deflection angle on the maximum force requirement for the process is greatest among design parameters. AA 6063 alloy is selected as a model material for the analyses in this study.