I In the cooling and air conditioning manufacturing industry, the efficiency of heat exchanger component production—particularly those utilizing copper tubes—plays a crucial role in improving system performance and reducing production costs. tube diameter expansion is required to facilitate the assembly process; however, it poses risks of defects such as cracking, wall thickness inconsistency, or structural failure due to excessive deformation.this study aims to detect potential failure in the flaring process of copper tubes (c1220t/c1220ts) by simulating the diameter expansion using cad-based modeling through simufact forming software. the finite element method (fem) is employed to model the material behavior during the flaring process. variations in plug die angles and punch stroke values are analyzed to examine their influence on forming limits, thickness distribution, and deformation parameters.the simulation results show that the plug die angle does not significantly affect the final tube diameter, but it does influence the values of effective plastic strain, equivalent (von mises) stress, and total displacement. the optimal punch stroke is found to be in the range of 13.9 mm to 14.1 mm, which yields defect-free deformation while keeping stress levels below the material’s yield strength (275 mpa).