Thermal-mechanical coupling calculation method for deformation error of motorized spindle of machine tool

•Considering the influence of milling force on the deformation of motorized spindle.•The thermal boundary conditions change with the rise of temperature.•The calculation of deformation is obtained by iterative thermal boundary conditions.•The thermal-mechanical coupling deformation is close to the actual deformation value.•The thermal-mechanical coupling deformation go up with the rise of rotating speed.