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There is now a CONTENT FREEZE for Mercury while we switch to a new platform. It began on Friday, March 10 at 6pm and will end on Wednesday, March 15 at noon. No new content can be created during this time, but all material in the system as of the beginning of the freeze will be migrated to the new platform, including users and groups. Functionally the new site is identical to the old one. webteam@gatech.edu
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Part I: Problems with critical ratio (CR) dispatching.
First, we examine the cycle time and on-time delivery performance of a semiconductor wafer fabrication facility (wafer fab) under critical ratio
(CR) dispatch regime. It turns out that determining appropriate due dates for this rule is a critical task. We provide a detailed analysis of the wafer fab behavior for a large range of due date values. From the results of the experiments we develop a heuristic for conservative due date estimates.
Part II: Comparison of due-date oriented dispatching rules.
In the second part of the talk we compare the cycle-time and on-time-delivery performance of the Critical Ratio (CR), the Earliest Due Date (EDD), and the Operation Due Date (ODD) dispatching rules in semiconductor wafer manufacturing. In addition, we comment on the robustness of the rules to low target flow-factor values. It turns out that EDD has almost no positive effect on on-time delivery compared to First-In-First-Out (FIFO) dispatching. CR and ODD, however, reduce the tardiness of lots considerably. ODD dispatching is more robust than CR if the target cycle times for the factory are chosen smaller than the corresponding average cycle times of a factory under FIFO dispatching regime.
Part III: Accelerating products for due-date oriented dispatching. In semiconductor manufacturing facilities, there is often the need to speed up certain product types. This is usually done by either assigning higher priorities or by reducing due dates. Here, we study the effects of accelerating one product type by a tighter due date on the on-time delivery performance of the other products manufactured. It turns out that the results depend on the considered factory, its load, and the accelerated product. As a consequence, it will be hard for production planners to find simple rules of thumb for the effects of accelerating products. In general, detailed simulation experiments will be required.
Biographical sketch:
OLIVER ROSE is Professor for Modeling and Simulation in the Department of Computer Science at the Dresden University of Technology, Germany. He received an M.S. degree in applied mathematics (1992) and a Ph.D. degree in computer science (1997) from the University of W
