Development of nomograms for prediction of extrusion stress for P/M copper preforms at warm working temperatures

The choice of correct magnitude of stress, in an extrusion process, is vital so as to obtain defect free components. Consequent to the involvement of various process variables like die angle, extrusion strain, billet aspect ratio, the determination of extrusion stress becomes difficult. Nevertheless, in extruding P/M preforms, persistent densification causes volume change resulting in further complications. Hence three nomograms are developed using ‘C’ program: (i) to predict the extrusion stress for hollow sintered P/M copper preforms; (ii) to predict the extrusion stress for solid sintered P/M copper preforms; (iii) to evolve stress ratio between P/M and ingot material. These nomograms serve as ‘ready reckoners’ for the prediction of extrusion punch stress in industries.