Abstract
This study investigates the effect of cutting depth on surface finish and dimensional accuracy in CNC turning of AISI 4340 steel using TiAlN - coated carbide inserts under dry conditions. A comprehensive experimental methodology was employed, incorporating precise control of machining parameters, surface topography measurements via profilometry and atomic force microscopy (AFM), dimensional inspection using coordinate measuring machines (CMM), and dynamic analysis through force and vibration monitoring. The results reveal a strong nonlinear relationship between depth of cut and both surface roughness and dimensional deviation. Surface quality remained stable at shallow depths (0.1 - 0.3 mm) but deteriorated sharply beyond 0.7 mm due to the onset of regenerative chatter. Similarly, dimensional accuracy declined significantly at greater depths due to increased tool deflection and thermal expansion. Cutting forces and tool wear exhibited exponential growth beyond 0.5 mm depth, with flank wear and edge degradation confirmed through SEM analysis. ANOVA results identified depth of cut as the most statistically significant factor influencing machining quality, with contribution ratios of 48.2% for surface roughness and 42.7% for dimensional deviation. The optimal depth of cut was identified within the 0.3 - 0.5 mm range, offering the best balance between material removal rate, surface integrity, and dimensional precision.