In the process industry, both quality and consistency of mid-term planning and short-term scheduling are crucial. We propose a sequential approach consisting in three steps : planning, lot streaming-pegging, and scheduling. This paper focuses on the intermediate problem that consists in cutting up the planned production in several lots (lot streaming) and linking stocks, lots and demands by determining material flows in circulation between these entities (pegging). We present a MILP formulation, and analyse its performance with regard to a heuristic approach.