Investigating the transition from ploughing to shearing in micromilling of additively manufactured Ti6Al4V

Compared with wrought Ti6Al4V, additively manufactured (AM) Ti6Al4V exhibits more severe machining difficulties owing to its lower thermal conductivity and higher hardness. AM components often possess lower ductility, anisotropic microstructures, residual stresses, and porosity-related defects, further complicating post-printing micromachining. With the growing demand for miniaturized and high-precision components, micromilling remains a crucial technique for producing features such as microgrooves and channels, and is expected to retain its importance for machining AM Ti6Al4V. However, micromilling faces challenges such as ploughing, excessive tool wear, and high specific cutting forces. This study examines the influence of ploughing and shearing on tool wear, surface morphology, burr width, surface roughness, and specific cutting force across varying feed rates and axial depths of cut. The results indicate a transition from ploughing to shearing as the feed rate and depth increase, improving cutting efficiency. Surface morphology efficiency improves from 81% to 97% (width) and from 75% to 98% (depth). Tool wear is highest at low feed rates and shallow depths owing to rubbing, while larger depths increase wear owing to greater tool engagement. Intermediate depths showed reduced wear. The percentage difference between experimental and ideal specific cutting forces decreases from 63% to 4% with increasing feed rate and depth. Surface roughness improves with increasing feed, but deteriorates at the highest depths, while burr width decreases with both parameters.