Publications

SLIM: Short Cycle Time and Low Inventory

SLIM is a set of methodologies and scheduling applications for managing cycle time in semiconductor manufacturing. SLIM includes methodology for calculating target cycle times and target WIP levels for individual manufacturing steps, heuristic algorithms for factory floor scheduling, and optimization-based capacity analysis. Between 1996 and 1999, Samsung Electronics Corp., Ltd., implemented SLIM in all its semiconductor manufacturing facilities. It reduced manufacturing cycle times to fabricate dynamic random access memory devices from more than 80 days to less than 30. Considering the decline of selling prices for dynamic random access memory devices, SLIM enabled Samsung to capture an additional $1 billion in sales revenue compared to the revenue it would have realized had cycle times not been reduced.

IMPReSS: An Automated Production-Planning

IMPReSS, an optimization-based production planning system at Harris Corporation's semiconductor sector, generates capacity-feasible production schedules for a worldwide manufacturing network and quotes product delivery dates in response to customer inquiries. The planning engine of IMPReSS is the Berkeley Planning System (BPS), which models the problem in a form that permits linear programming optimization. BPS embeds formulation techniques for planning the requirements of binning and substitutable products, for representing dynamic capacity consumption by reentrant process flows, and for developing multiple optimization calculations that reflect marketing priorities. It uses a heuristic decomposition strategy to break the overall problem into several manageable calculations. Its implementation raised on-time deliveries of line items from 75 to 95 percent without increasing inventories, enabled the sector to expand its markets and its market share, and helped move the sector from a loss of $75 million to profit of over $40 million annually.