The representation of manufacturing resources plays a fundamental role in engineering modeling scenarios. These are characterized in a number of ways by taking into account their physical properties, capabilities, roles, etc. In this context, notions like capability, process, and functionality are used in different manners, hence it is not clear how different approaches can interoperate. The aim of this work is to propose an ontology for manufacturing that represents assets involved in manufacturing operations, their characteristics and relations, as defined in a list of requirements. This contribution stems from the existing literature and, in particular, integrates recent works related to the modeling of manufacturing resources, engineering functions, and capabilities. The ontology takes advantage of DOLCE as foundational ontological framework. The relevant axioms are presented and commented on with respect to the identified requirements.