Analysis of Spindle Speed Influence on Surface Roughness and HSS-Co Tool Vibration in The Turning of ST 41 Steel Using the Taguchi Method

Abstract

Surface roughness and tool vibration are critical parameters in machining, as they directly influence product quality and tool life. This study investigates the effect of spindle speed on surface roughness and the vibration velocity of an HSS-Co (5% cobalt) cutting tool during the turning of ST 41 steel. The Taguchi method was applied using an L8 orthogonal array and Signal-to-Noise (S/N) Ratio analysis to determine optimal cutting conditions, while Analysis of Variance (ANOVA) was used to identify the most influential factor. Turning experiments were conducted on a conventional lathe with spindle speeds varying from 100 to 700 rpm and a constant depth of cut of 0.5 mm. Surface roughness was measured using a surface roughness tester, and tool vibration was recorded with a vibrometer. The experimental results show that higher spindle speeds consistently reduce surface roughness, indicating improved machining quality. The lowest roughness value of 9.31–9.32 µm was achieved at a vibration velocity of 19.43 mm/s, whereas the highest roughness of 21.62 µm occurred at a vibration velocity of 5.81 mm/s. Taguchi analysis confirms that spindle speed is the dominant factor influencing both surface roughness and tool vibration stability, as reflected by significant variations in S/N Ratio across the tested levels. Overall, this study demonstrates the effectiveness of the Taguchi method for optimizing machining parameters in conventional turning. The findings provide practical insights into selecting spindle speeds that enhance surface quality while maintaining cutting tool stability during the turning of ST 41 steel with an HSS-Co tool.