The concept of combining the latest finite element (FE) and discrete element (DE) multiscale numerical technologies for modelling of the tool/workpiece interface during high shear processing is described. The potential of FE tools and techniques merged with DE based transient dynamics is highlighted. Linking of the modelling scales is based on transferring the corresponding boundary conditions from the macro model to the representative cell, considered as the meso- level model. This meso- model consists of a large number of bodies that interact with each other. The transfer processes are described by the system of diffusion and motion equations including contact detection and interaction solutions for particles integrated in time. Modelling of the tool/workpiece interface including both mixing of the oxide particles into the subsurface layer during hot rolling of aluminum and heat generation during friction stir welding (FSW) are considered.