In this study, a milling force model based on finite element simulation of orthogonal cutting process has been proposed. Design of computer experiments approach is used to obtain a metamodel based on finite element simulation results of machining titanium alloy Ti6AL4V. The metamodel is integrated into an analytical milling force model including tool runout effect to calculate milling forces at micro and macro scales. The proposed model yields results that are in good agreement with measured milling forces.