Emerging economies and new ways of doing business are changing the world in a dramatic manner, these changes suggest that new competitive advantages must be created within companies to belong capable to develop customized products and cost effective manufacturing systems. New manufacturing systems are required to create new generation of manufacturing systems, which must be easy to increase in capacity, easy to update and capable to integrate, new technologies. All this will allow new products launching successfully, as well as any adaptation to the manufacturing system due to changes demand; it will be possible quickly to integrate new functions and technologies to the new manufacturing systems, and by consequence the capacities of those systems will adjust to the market necessities and changes. This research proposes a systemic methodology to design reconfigurable manufacturing systems. Reconfigurability is an attribute to develop within companies in order to respond rapidly and cost effective to market demands. The methodology to design manufacturing systems is based on systems engineering life cycle. The methodology is structured in three main phases: Manufacturing System Analysis, Manufacturing System Design and Manufacturing Operations and Maintenance. Manufacturing systems need a degree of reconfigurability since its design and during the operation. The methodology incorporates Digital Manufacturing tools to support strongly the manufacturing systems design. Through the use of these tools it is possible to design manufacturing systems in a virtual environment to minimize error production. The case studies reported in this thesis were developed in an Automotive Manufacturer company. The first case is the virtual design of an arc weld cell and the second one is the development of a resistance spot weld cell. Both case studies required to give a level of reconfigurability in product, volume, process and layout.