An extended scheduling model for producing corrugated boxes

Today, custom and shipping regulations recognize the importance of lightweight and high performance corrugated boxes, and encourage wider usage of them. Usually, the boxes are produced by glueing layers of paper from roll stocks and cutting carton boards in certain sizes in the corrugater machine, drying them in the buffer area, and converting the flat boards into boxes in the converting machines. Similar to previous work, this study also deals with the cutting stock, buffer utilization and machine loading problems. Additionally, it includes set-ups in the converting machines and operating characteristics of roller conveyors in the buffer area. A binary linear program is proposed to maximize the total length of converted paper boards in one shift and to minimize the percentage trim loss. An optimal decomposition algorithm is developed to employ Successive Linear Programming Relaxations until the upper bound on the throughput is reached. An experimental study, with the real data obtained from a local company, indicates that implementable optimal solutions can be efficiently achieved. Furthermore, an approach is proposed for conducting the trade-off studies between the total throughput and the total trim loss.