The application of Artificial Intelligence in a manufacturing environment is described. Starting from the idea in 1985 that an expert system would work, to the full-fledged working application in 1987, it is shown how the system used by the Northrop Corporation's Aircraft Division is performing with the full support of the management. The Expert System Planner, (ESP), is described that performs generative process planning for parts fabricated from extruded and sheet metal materials. The Knowledge Engineering Environment (KEE) software from Intelli-Corp was used.