Establishing an optimal production schedule for a food or beverage plant is a challenging task.  The best lot sequencing and sizing must be developed considering the multitude of products, packaging formats and filling lines capacities and cleaning constraints.  This paper demonstrates how a discrete events simulation model of a dairy plant has been developed to represent milk pasteurizing, holding and filling processes.  The model was designed with and validated by dairy technology experts, process engineers and production coordinators.  The goal was to create a tool to support: selection, sizing and validation of new equipment, de-bottlenecking of ongoing operations, optimization of total operating time, and elimination of undesired waiting times.  The strength of this model is to capture most of the multidisciplinary planning team know-how; a person could generate a quasi-optimal schedule in a short amount of time.  The model helped in reduction of waiting and changeover times, estimation of additional volumes that could be accommodated and also supported an important plant expansion study.  Capitalizing on the fact that the simulation and its results were consensual, the project team used it as a risk assessment tool.