A Production Planning and Scheduling Methodology for the Virtual Enterprise Applied in the Semiconductor Industry

Abstract

A Production Planning and Scheduling Methodology for the Virtual Enterprise Applied in the Semiconductor Industry The virtual enterprise (VE) is gaining importance in today's economic environment. The trend was first observed in the semiconductor industry but different factors support it and trigger a widespread use in other environments. A VE consist of a core company that has the market channels, the product know-how and some of the required in-house production capabilities. It has been growing and part of its production is subcontracted to satisfy demand. This dissertation defines a "Virtual Enterprise Construct" as the VE order routing that is the result of a set of Make or Buy decisions. The subcontracted part of the order routing will have specified start- and completion times and is frozen. The methodology combines a rough- and a fine optimisation pass. The rough pass builds schedules using heuristic- or rule based (human guidance) algorithms. It offers the planner fast answers to "what if" scenarios and order progress disturbancies in the VE. The fine pass improves the rough schedule to a more efficient schedule for the whole VE, both in cost and VE unit loading, without violating any of the already taken engagements and without the need of another descriptive VE model. The stepwise refinement from rough to fine schedule offers the planner a trade-off between efficiency and computation time. The ability of the methodology to work with frozen schedules and subcontracting VE units disclosing only sparse resource information (e.g. possible start- and completion times of an order request) and its capacity to integrate local VE units' work schedules in a VE wide planning makes its also suitable for usage in the emerging enterprise networks.