Optimization of wet drawing according to the ratio of breaking stress to draw stress

The paper continues the previous authors’ works in the field of wet wire drawing. The process of wet fine brass-plated steel wire drawing is considered. The subject of the paper is increase of the wire die wearability. The analysis of various wire drawing tools (hard alloy dies, synthetic diamond dies, natural diamond dies) was carried out for the relevance of its application for small diameter wire drawing. The authors studied the wire die wearability. The research methodology is presented, which include the procedure and conditions for measurements, industrial equipment and type of wire drawing machine. In the paper, the comparative analysis of the experimental data with the results of other authors for similar wire drawing tool was carried out. The authors calculated the main characteristics of the wire die wearability distribution (asymmetry, kurtosis, coefficient of variation). A statistical analysis of the array of experimental data for selection of more than 500 samples was performed. A high correlation of the drawing die wearability with the ratio of breaking stress to draw stress and a weak correlation with the drawing force and stress were revealed. The highest and most stable die life results are achieved when ratio of breaking stress to draw stress has values of 1.9 – 2.5. A formula was proposed for determining the optimal value of the ratio of breaking stress to draw stress, depending on the wire diameter. The formula allows one to determine the maximum die wearability values, depending on the wire drawing schedule. The work results can be used when designing new wet wire drawing schedules using synthetic diamond dies.