Virtual manufacturing is a new and emerging concept to integrate different areas of manufacturing by using computer technology for creation and execution of virtual models. Virtual manufacturing is defined as a computer-based system, which consists of evolving models of manufacturing systems and processes, and exercised to enhance one or more attributes of the real system. Manufacturing as a whole is a very complex system consisting of various interacting, interrelated and interdependent subsystems and processes. Construction, validation and calibration of an all-inclusive virtual manufacturing system is difficult and sometimes impossible. The object-oriented approach suggested will help to simplify this task. The entire virtual system is now constructed using smaller blocks or objects. Each object is a sub-model, which is created, validated and calibrated independently. Various objects are integrated at different levels to form higher-level subsystems which in turn create the whole system. The concept is illustrated with the example of a virtual machining operation, representing one of the smallest building blocks in the comprehensive virtual manufacturing system. Results from real experiments were used to validate and calibrate the virtual machining operation and to prove its adequacy.