A decision-making approach for nesting scheduling: a textile case

In many industrial cases, the nesting problem and the scheduling problem have to be addressed at the same time. The complexity of the combined problem often prevents to take effectively into account both nesting efficiency and overall production objectives. This paper presents a scheduling approach for the combined problem of production scheduling and nesting. The aim of the proposed approach is to provide a good solution both for the nesting and scheduling problem. The approach involves the generation of scheduling alternatives, their transformation through a rule base mechanism into nesting solutions and finally their evaluation using different criteria that reflect the overall production objectives such as meeting due dates, minimizing of the cost and maximizing the machines and stock sheet utilisation. The proposed approach has been implemented in a software system for the purpose of solving a problem in the textile industry. Specifically, the scheduling of the carpet weaving process - a problem of nesting rectangular patterns under complex production constraints - has been examined. A set of experiments has been conducted for producing realistic nesting schedules in order to evaluate the proposed system's performance. The results show that the proposed approach may be applied in real-life manufacturing processes under complex production constraints and multiple objectives.