Many textile products are using materials with higher thickness like foams, spacer fabrics and nonwoven materials in order to provide comfortable softness of the contact surface to the body. Such materials are often joint to another external layer who have to provide optical and mechanical stability of the system, and are joined together into a 3-dimensional geometry. This paper analyses some steps of joining such materials by sewing. The forces in the sewing threads are analyzed analytically. A numerical model based on finite element method (FEM) is implemented in LS-Dyna and the process of compaction of the sewing line, based on the thread force is simulated. The thread force propagation is numerically analyzed in the time, at different friction coefficients and for different foam stiffness. All simulations demonstrate logical results and can be used as a fundament for more complex investigations and optimizations of such products.