This paper proposes a manufacturing core concepts ontology (MCCO) aimed at providing support for product life cycle interoperability. The potential focus of the work is interoperability across the production and design domains of product lifecycle. A core set of manufacturing concepts and their key relationships are identified in MCCO. Semantics are captured formally through heavyweight logic using rigorous rules and axioms. Three different levels of specialization have been identified according to the degree of specialization required. Each level provides an immediate route to interoperability for the concepts specialized from that level. MCCO enable knowledge sharing across design and production domains through core concepts. A successful initial experimental implementation has been done to demonstrate the working of MCCO.