A Simulation-Based Scheduling and Management Information System for a Machine Shop

This paper describes the design, working, performance, costs and benefits of a computerized scheduling and management information system that has been developed for a large, generalized m / n machine shop which had previously been a bottleneck facility in the Cast Roll Manufacturing complex of Bethlehem Steel Corporation. A flexible discrete-event simulation model, at the heart of the computer system, generates two types of schedules: Planning Schedules for making long- and medium-term planning and operating decisions, and Production Schedules for sequencing approximately 1,000 rolls on 40 machines on a day-to-day basis.A number of supporting programs perform data management, file management, and report-generation functions. Data-collection functions are deliberately performed manually to avoid the high costs associated with automatic data-collection equipment normally used in large computer systems. The computer programs are run in a time-sharing environment. A cathode ray tube and a medium-speed printer are the only hardware requirements of the system. With the implementation of the computer system, significant improvement is now being obtained as measured by productivity, labor and machine efficiencies, due date performance, and work-in-process inventory. The computer system is saving Bethlehem a substantial amount of money every year, and a notable feature of this system is its low annual operating cost.