<p>Aluminum 6061-T6 alloy is widely used in the aerospace industry and is known for its excellent machinability. However, machining thin-walled components using the alloy presents unique challenges such as high surface deviation, high surface roughness and heavy tool wear. This research paper investigates the effects of cutting parameters and cutting conditions on surface characteristics of thin-walled Al 6061-T6 alloy. Experiments were conducted under dry and cryogenic conditions by varying feed, spindle speed, depth of cut and tool diameter, using CNC milling to analyze surface deviation and surface roughness in 1, 1.5 and 3mm thin-walls. Surface deviations and surface roughness are measured using precise equipment over the designated locations on the thin-walls. Using the Taguchi-Grey Relation Analysis (GRA) Technique, the process parameters are optimized for reducing surface deviations and surface roughness. The significant parameters and their value according to their ranks are cutting tool diameter (10mm), spindle speed(6000rpm), depth of cut(0.3mm), cutting condition (cryogenic) and feed rate (3000mm/min). The results indicate that optimizing cutting parameters under cryogenic conditions can significantly improve machining efficiency and can also reduce the risk of defects in thin-walled components (surface deviation and its standard deviation reduction up to 45.41 and 78.18%). However, the surface roughness increases (up to 20%) and its standard deviation (up to 7.84%), which can be controlled through a combination of process parameters. This research presents a solution for the aerospace industry, outlining machining thin-walls in Al 6061-T6 with optimized process parameters. The research focus is to attain enhanced surface integrity with the least surface deviation and a higher surface finish.</p> Graphical abstract <p></p>