###### Abstract  
Titanium grade 9 (Ti-3 Al-2.5V) stands out as a preferred material in various industrial applications because of its suitable properties. Its applications span diverse sectors, including precision manufacturing, where it is utilized to produce honeycomb structures for advanced aeronautics, as well as for certain biomedical components. In parallel, micro-milling has gained widespread utilization across medical, aerospace, and electronic industries due to the increasing demand for miniature products in these domains. This current research study aims to explore the impact of various micro-milling process parameters--specifically, feed rate, cutting speed, and depth of cut--on the surface quality, burr formation, and tool flank wear of titanium grade 9. Research findings reveal that the feed rate plays a major role in influencing surface roughness (contribution ratio (CR): 62.96%) and burr formation (CR: 55.20%). Similarly, cutting speed and depth of cut significantly affect surface roughness, contributing 20.32% and 9.27%, respectively, but are insignificant factors for burr width. Tool flank wear is primarily influenced by cutting speed (CR: 54.02%), with feed rate contributing 33.18%. Additionally, the feed rate and cutting speed are significant factors in determining the length of the burr, with contribution ratios of 77.70% and 7.77%, respectively. Confirmatory tests conducted at optimum parameters selected from the main effects plot validated the experimental results. Titanium grade 9 (Ti-3 Al-2.5V), titanium alloy (grade-9); micro-milling; analysis of variance; burr formation; tool flank wear; surface roughness +
Footnote †: journal: Applied Softof titanium alloys with intricate features and exceptional surface quality [1]. Although micro-milling offers numerous advantages, it also presents several challenges in the process of producing micro-devices [2]. Burr is a common byproduct in subtractive manufacturing processes like machining. In micro-milling, the burr size is significantly smaller than in macro-scale machining, making burr removal a more difficult task in this domain [3; 4]. Micro-machining, in contrast to other micro-level techniques for producing micro products, provides greater flexibility in the production process. With no limitations on shape cutting, it can create intricate structures, including arbitrary curvatures, three-dimensional cavities, and high-aspect-ratio features like long shafts and micro-channels [5]. Micromachining techniques offer a competitive advantage due to their cost-effective setups and high material removal rates compared to nontraditional micro-machining processes. This makes them a viable option for producing customized items or small batches. However, micromachining is limited by the choice of suitable workpiece materials. Achieving fine surface finishes, particularly in finishing processes, is crucial for high-precision components. In the realm of surface roughness research, the primary focus has been on modeling and selecting appropriate parameters. The micro-level milling process presents various challenges, with the most significant being the characterization, reduction, and evaluation of burrs. Tool life is determined by tool flank wear, which results from the direct interaction between the tool face and the workpiece. This interaction also affects surface quality. In the micro domain, the stringent requirement for surface finish amplifies the importance of preventing tool failure [6]. Titanium alloys are known for their poor machinability due to low thermal conductivity. In micro-scale machining like micro-milling, cutting tools in titanium alloys quickly wear out [7]. Researchers conducted a study on optimizing machining processes to achieve sustainability, productivity, and efficiency simultaneously. They analyzed the effects of machining parameters and conditions, with a focus on specific cutting energy, tool wear, surface roughness, and material removal rate.