A COMPARISON OF AN CP AND MIP APPROACH FOR SCHEDULING JOBS IN PRODUCTION AREAS WITH TIME CONSTRAINTS AND UNCERTAINTIES

摘要

This research is motivated by the expensive cost of scraps because of timelink misses in a semiconductor manufacturing line due to tool downs. A timelink is a time constraint between defined process steps. This paper presents a mixed integer programming model (MIP) and a constraint programming model (CP) with downscaled time constraints. With the assistance of the survival analysis, a safety value will be computed and included as a constant in the MIP and as a dynamic expression in the CP, to downscale the allowed time between two specific operations. The MIP and CP models are tested on a realistic production area example with different problem sizes. The quality of the solution and the performance of these two approaches are compared with each other. The test results show that the CP model outperforms the MIP and quickly finds much earlier usable schedules for large problem sizes.