Cutting Temperature and Surface Roughness in Turning of Wire Arc Additively Manufactured Aluminium Alloy Parts

Wire Arc Additive Manufacturing (WAAM) based on Cold Metal Transfer (CMT) welding produces near-net-shape metallic components, but post-process machining remains essential for dimensional accuracy and surface quality. This study investigates the dry turning machinability of EN AW-5083 aluminium alloy parts produced by CMT-based WAAM, focusing on tool-holder temperature (Tth) as a relative thermal indicator and surface roughness. Tth was monitored with a K-type thermocouple embedded in the tool holder and an Arduino-based data acquisition unit, while surface roughness (Ra) was measured with a portable contact profilometer after each pass. Three machining parameters—cutting speed, feed rate, and depth of cut—were investigated using a Taguchi L18 orthogonal array, with significance assessed through S/N ratio analysis and ANOVA. Grey Relational Analysis (GRA) was applied for multi-response optimisation, benchmarked against published machinability data for wrought and WAAM-fabricated aluminium alloys. Surface roughness was governed predominantly by feed rate, while Tth was most strongly influenced by depth of cut. The combined Taguchi–GRA optimisation identified a parameter set minimising both responses simultaneously. Benchmarking against three literature sources showed that the surface roughness achieved for the investigated CMT-WAAM material falls within the range reported for wrought EN AW-5083 under comparable machining conditions. These findings provide practical guidance for post-process machining of WAAM-produced aluminium components in hybrid manufacturing chains.