Experimental and numerical study of optimal die profile in cold forward rod extrusion of aluminum

In this paper, the effect of die profile on the variation of stress and load in the cold forward extrusion of aluminum has been studied. The aim of this research is the reduction in deformation load, improvement in the metallurgical properties of the product and increasing in the die life by means of an optimum die profile. In this respect, the stress and load relations in forward rod extrusion for curved profiles have been obtained by using the slab method. In addition, by using a developed computer program, the optimum die profile has been obtained considering work hardening of the material in cold extrusion, on the basis of minimization of stress and load in die–workpiece contact surface. The obtained profile depends on the extrusion ratio, material properties of the workpiece and coefficient of friction which are the input parameters to the program. By using the finite-element software, ABAQUS, the optimum die angle for the conical die in the same conditions is determined. Furthermore, the finite-element and experimental load–displacement curves have been determined. The obtained results illustrate that the cold extrusion load for aluminum in the optimum curved die is considerably reduced, compared with that in the optimum conical die.