SURFACE ROUGHNESS ANALYSIS OF SLM-PRODUCED TI-6AL-4V MILLING USING TAGUCHI DOE
Abstract
Selective Laser Melting (SLM) is an advanced additive manufacturing technique widely used to produce Ti-6Al-4V components with complex geometries and high material efficiency. However, SLM-produced Ti-6Al-4V commonly exhibits surface irregularities and a hardened microstructure, which necessitate post-processing by machining to achieve the required surface quality. Surface roughness is a critical parameter that influences the functional performance, fatigue life, and reliability of machined components, particularly in high-precision applications such as biomedical and aerospace engineering. This study investigates the surface roughness behaviour during milling of SLM-produced Ti-6Al-4V using a Taguchi-based Design of Experiments (DOE) approach. An L9 orthogonal array was employed to evaluate the effects of three machining parameters—spindle speed, feed rate, and depth of cut—each at three different levels. Surface roughness was assessed using the arithmetic mean roughness (Ra), measured with a contact-type surface profilometer. The experimental data were analysed using signal-to-noise (S/N) ratio analysis, supported by analysis of variance (ANOVA) to determine the contribution of each parameter. The results indicate that spindle speed is the most influential factor affecting surface roughness, contributing approximately 83.66% to the total variation. The optimal machining parameters for minimizing surface roughness were identified as a spindle speed of 7000 rpm, a depth of cut of 0.1 mm, and a feed rate of 1200 mm/min. These findings demonstrate the effectiveness of the Taguchi DOE method and provide practical guidance for optimizing milling parameters in post-processing of SLM-produced Ti-6Al-4V components.
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