The evolution of aerospace products, with an increasing number of components, more demanding delivery times, and reduced costs, is leading companies to look for integrated management systems. The future of the aerospace industry is linked to the development of new methodologies, such as Model-Based Engineering (MBE). In the last two decades, the use of semantic structures, such as ontological models, to improve information systems has proven to be very effective in the industry. Models for Manufacturing (MfM) is a recent OBE (Ontology- Based Engineering) methodology for defining complex manufacturing systems’ data, functions, and behaviours using graphical models. It is based on agnostic tools and is structured in an architecture of three independent layers. In this paper, the MfM methodology is applied to describe the manufacturing process of Aerospace Sheet Metal (ASM) parts. The implementation is described through a practical example for a part manufactured with one of the most used sheet metal forming processes in the aerospace industry: hydroforming. A study analysed 26 typical sheet metal parts, finding bending and hydroforming to be the main processes. The model aims to characterize the forming process, i.e., to recognize the most appropriate manufacturing process, and subsequently to define the necessary operations and resources, based on the part’s Computer Aided-Design model. In addition, the model is complemented by other existing MfM tools for sheet metal forming.