Friction coefficient in the process of direct extrusion of wire and bar solder from 52In-48Sn alloy

In any metal forming process, there is external friction at the contact between the tool and the material being processed. Under the influence of friction forces, the deformation force increases, the tool heats up and intensively wears out, the deformation unevenness increases and, as a result, the microstructure of the metal being processed becomes heterogeneous, tensile stresses arise, which sometimes lead to disruption of the product continuity. This article examines contact friction during the direct extrusion 52In-48Sn alloy bars and wires. Using mathematical modeling, the influence of the friction coefficient on the force during extrusion of bars Ø8.0 and 15.0 mm, as well as wire Ø2.0 mm, was investigated. It is shown that with an increase in the coefficient of friction to overcome the sliding friction force on the contact surface of the metal with the container and with the matrix, up to 60% of the effort required for extruding the alloy under study is spent. Experimental studies have shown that the use of lubricants, namely graphite (graphite - C) and molybdenum (molybdenum disulfide - MoS2) lubricants, can reduce the friction coefficient by more than 10 times. With a certain degree of assumption, we can say that when extruding 52In-48Sn alloy solder using a steel container without the use of lubricant, the friction coefficient is 0.5, and when using graphite or molybdenum grease, the friction coefficient will take values close to 0.05. Using the results of experimental studies, by the selection, the friction coefficient was determined according to the laws of Coulomb, Siebel and Levanov, which can be used for computer modeling in the Qform package for direct extrusion 52In-48Sn alloy solder using a steel container without lubrication and using graphite and molybdenum lubricants. Considering the reliable value of the friction coefficient in computer simulation will significantly increase the accuracy of calculations.