AbstractFactory modelling is a mathematical description in terms of state equations of the dynamics of factory facilities, such as machines, transport devices and stores, where manufacturing processes are actuated by a production control system to yield market- or customer-oriented products.Factory modelling is preliminary to the design of the production control system, i.e. of the set of devices and rules that allow a manufacturing system (the whole of factory facilities and their feasible manufacturing processes) to track with the least possible error a variable product mix.Although several methodologies for modelling factory dynamics have been worked out and implemented in recent years, no systematic approach for production control design, based on state equations, has so far been available. Hence a new modelling framework has been worked out and its foundations are presented in this paper.