Production improvements using a forward scheduler

One of the fabricators at the IBM Microelectronics Division's manufacturing facility in Essex Junction, Vermont, is a high volume producer of DRAM's and advanced logic products. The wafer processing line is controlled by several custom software systems distributed over multiple mainframe host computers. The IBM Forward Scheduler used in this fabricator is a product scheduling system that provides an environment where information from many CIM system data sources can be integrated. Four times each day, data is automatically downloaded to an IBM RS/6000 workstation from sources containing information related to work in progress (WIP), product routings, operations, parts, and tools. The data is inspected, processed and converted to a file format consistent with Tyecin's 'ManSim' software, a commercial manufacturing simulator. A simulation of the manufacturing line is run for 48 hours, generating several short-term dispatch reports by fabricator, area, and workstation. The reports, which contain hourly projections of product movement, are then uploaded from the RS/6000 to a VM machine, viewed and used by manufacturing personnel for future tool and labor allocation (e.g., scheduling of meetings, preventive maintenance, overtime and vacation, and tool deployment). This paper describes the software system and interfaces of the Forward Scheduler as well as the issues involved with calibrating a short-term line simulator, how manufacturing personnel use the simulated data, and the system design features that minimize maintenance on the Forward Scheduler.