This paper presents an approach to describe business process in production systems using workflow concepts. In this sense, we define an extension of the UML Activity Diagram called Workflow Activity Diagram (WAD) which applies the C-WF model concepts. The C-Wf model represents the structural and functional enterprise objects involved in the business processes, such as enterprise activities, human resources, machine resources, etc. The WAD depict the workflow model identifying its activities and resources required for its execution defining its relationships and sequentially. By the intensive use of UML use cases, our approach reinforces the usability of UML in the context of business modeling.