FMS ensures quality product at lowest cost while maintaining small lead-time. So, firms adopt FMS as a means of meeting burgeoning requirements of customized production. Main purpose of FMS is to achieve efficiency of well-balanced transfer line while retaining the flexibility of the job shop (Stecke, 1983, 1985). A flexible manufacturing system (FMS) has four or more processing workstations connected mechanically by a common part handling system and electronically by a distributed computer system. It covers a wide spectrum of manufacturing activities such as machining, sheet metal working, welding, fabricating, scheduling and assembly. There are some scenarios in scheduling of parts in FMS
where adequate slack is provided in the system to negate the undesirable impact of interruptions and need not requires any rescheduling. The slack time is defined as the difference between the cycle time and the elapsed/processing time. However, there are a number of situations where the slack in the system affects the performance of the system and
require corrective measures. In this regard, the authors have developed extrapolative schedules, which efficiently take care of the disruptions on the shop floor and retain the high performance value of the system