Implementing new dispatching rules at SGS-Thomson Microelectronics

This paper reports a real-life manufacturing case study in the short term production planning and control for a very large scale integrated (VLSI) circuit manufacturing production unit Dispatching in VLSI manufacturing is a crucial issue, since often binding constraints are set on the delivery dates by the customers downstream in the supply chain, while manufacturers , due to the huge fixed cost of capital goods, must ensure the full utilization of their shop floors. The complexity of the manufacturing technology and the re-entrant nature of the resulting production flows further add difficulties to the problem. Starting from a shop floor scheduling based on simple dispatching rules, e.g. FIFO rule, or the well-known 'minimum set-up' criterion, workcentres have been firstly grouped according to their nature, then they have been classified according to their criticality in terms of production capacity and flexibility. Finally, for each class, a customized, yet suitable to be implemented, dispatching rule is proposed and tested through a wide simulation campaign. Experimental results show that the proposed dispatching approach leads to a superior overall output and, at the same time, to an increased delivery timeliness.