There is a trend in some manufacturing industries to move from selling products to providing services. As a result, designers must consider the life-cycle costs. In the aero industry, for example, this must be considered as well as weight, performance and manufacturing cost. The IPAS (Integrated Products and Services) project is intended to utilise Semantic Web technologies in order to provide feedback of information/knowledge acquired during operation of a product to the product's designers, and also to reuse knowledge from previous product designs. As part of IPAS, ontologies describing the products and processes have been created in order to allow service knowledge to be represented and shared. The design and implementation of these ontologies, and their planned future evolution, is described here. We also try to draw some lessons from our experiences.