Virtual production line based WIP control for semiconductor manufacturing systems

The explosive growth of data acquisition and increasing number of machining processes makes extremely difficult to deliver precise information to the proper users at the right time by relying on a centralized work-in-process (WIP) control system in manufacturing. This article presents a potentially practical solution to a manageable and well-distributed WIP control system by addressing issues such as real time performance, scalability, and reconfigurability. By taking advantage of the advances in distributed computing technologies multiple WIP control instances performing different subsets of control and management responsibilities can be spawned from a server repository, running on geographically dispersed networked computers. These spawned WIP control instances are coordinated and synchronized using the concept of virtual production lines (VPLs). WIP control algorithms for implementing real time "pull" operations, leveraging WIP levels, and resolving resource sharing are proposed. Certain validation has been conducted in an industrial testbed to confirm the applicability of the proposed VPL-based WIP control solution. (C) 2004 Elsevier B.V. All rights reserved.