Resolução do problema do sequenciamento de lotes aplicado à produção de papel-cartão

Abstract

Paperboard is a broadly utilized material in packaging industry. Such industry is on solid rise in this century, due to the global increase in purchase of industrialized products and e-commerce. As a consequence of coronavirus pandemic, which started on late 2019, packaging paper demand has increased, due to the essentiality of food and health supplies and greater utilization of delivery services. Since paper price is defined by market and the differentiation is small among industries, the optimization of production planning plays a decisive role in reduction of expenses and increase of profit. For the development of this work, data were provided by a packaging paper industry in Brazil, which produces paperboard of various grammages and compositions. The objective of this work consists in solving the lot scheduling problem in a paperboard machine, aiming to minimize costs related to losses caused by changeovers between products. Some of the products are constantly withdrawn by the client, therefore a minimum stock level must be held for those. Two methods were proposed to solve the scheduling problem. One is a mixed integer programming formulation, based on the prize collecting traveling salesman problem, and the other one is a greedy, randomized and adaptive construction heuristic. Both methods leaded to sequences which respected the operational constraints and met the established demands, and a considerable decrease in the total setup time was observed.