Scheduling of a paper mill process considering environment and cost

This study presents a new decision making method for scheduling paper mill processes, especially for the paper converting process. The optimal scheduling is analyzed with the multiobjective optimization programming (MOOP) using the summation of weighed objective functions (SWOF) [Ko and Moon, 2002]. In the production planning for the paper converting mill, making the strategy for the cutting paper is the bottleneck problem. In other words, how to cut papers efficiently with the raw paper reel is critical and this is called the trim loss problem. Environment (a waste amount) and energy cost are generally conflicting objectives. To reduce the environmental waste of the trim loss requires higher energy cost by moving the cutters. The MOOP is an applicable method to satisfy both objectives simultaneously. The MOOP algorithm includes normalization, SWOF and Pareto point analysis steps. The amount of trim loss and production cost are considered objective functions under the concept of taking into account both economy and environmental impact in its scheduling. The constraints are to satisfy with order, minimum profit level, etc. Here, the compromised solution set is identified based on Pareto points. The decision maker can select the practical solution for scheduling of paper mill process with the satisfaction of both environmental and economic requirement.