This article describes starting-up an automation process based on applying group technology (GT). Mecanizados CNC, a company making metallurgical sector products, bases the layout (organization and disposition) of its machinery on the concept of manufacturing cells; production is programmed once the best location for the equipment has been determined. The order of making products and suitable setting up of tools for the machinery in the cells is established, aimed at minimizing set up leading to achieving 15% improvement in productivity.