A project-oriented production model of batch plants

This paper presents a project-oriented framework for interactive analysis of the feasible plans and schedules that can provide an effective/efficient flow of orders within a batch process. The proposed approach is based on a hierarchical project-oriented production model that integrates production planning with short-term scheduling and resource leveling, At the highest layer of the hierarchy, the use of aggregate activities and their milestone dates is aimed to emphasize a management perspective of the production model. As a core element of the model a process task network is used. Each node of this network is expanded further into sub-tasks and their detailed schedules. Efficiency in resource's usage during short-term scheduling is improved by changing process task durations. The implementation of the project-oriented production planning methodology has been based on the existing literature in project management (Leachman, 1982, Leachman, 1983; Hackman and Leachman, 1989), but many alternative techniques can be used for specific layers (sub-problems) of the proposed hierarchy. An attractive feature of the project oriented approach is that descentralized decision making is favored. Conflicts between management objectives and shop-floor decisions are solved iteratively in a two-tier scheme. Simple examples are considered to illustrate the potentials and advantages of the project-oriented approach. (C) 1998 Elsevier Science Ltd. All rights reserved.