A lot-sizing and scheduling model for multi-stage flow lines with zero lead times

We present a new model formulation for lot-sizing and scheduling of multi-stage flow lines which works without a fixed lead-time offset and still guarantees a feasible material flow. In the literature, multi-stage lot-sizing model formulations often use a fixed lead time offset of one period leading to increased planned lead times. Computational tests have shown that the total costs resulting from our new model formulation are at least 10% lower. Furthermore, we present a solution approach based on Fix-and-Relax and Fix-and-Optimize. Numerical results show that this solution approach generates high-quality solutions in moderate computational time.