This paper deals with a numerical formulation of coupled thermo-mechanical contact for casting analysis. The final goal is to get an accurate, efficient and robust contact model, allowing the numerical simulation of solidification processes in the metal casting industry. Different algorithms to deal with the mechanical constraints induced by contact such as penalty, augmented lagrangian or a novel block-iterative solution are compared. A heat conduction model depending on both temperature field and contact pressure has been considered. Furthermore, the isolating influence of the air-gap between the cast and the mould has been taken into account for the definition of the convection heat transfer. The different alternatives have been implemented into the finite element code VULCAN developed by the authors. Numerical simulations of solidification processes are presented showing the performances of the computational contact algorithm developed.