Statistical modelling of surface hardness and roughness in cold extrusion of aluminium

This paper describes the application of the surface response method in an attempt to define a relationship between both the surface hardness and roughness of extruded aluminium billets, and three process parameters, namely; the conical die angle, die land height and die exit diameter. A programme of experimental extrusion of aluminium was carried out in parallel with statistical modelling. An adequacy test was made on the analysed models to determine the accuracy with which the model predicted data obtained by experimental methods.