No-wait lines optimisation: a procedure based on scheduling enhanced by digital twin

Abstract The no-wait scheduling problem involves planning the sequence of tasks in a job without any delay. This constraint is crucial in industries where production interruptions may create significant inefficiencies or quality issues. This paper addresses this problem by proposing a new methodology to design and verify a work-cycle related layout, focusing on both job-shop and flow-shop environments and finally proving its efficiency thanks to the use of a digital twin to validate the production process. The goal of the optimisation is the makespan minimisation and it is achieved through the application of the timetabling heuristic method. The iterative nature of the proposed model allows for a continuous improvement in scheduling, and queue reduction is verified thanks to the digital twin. The iterative procedure is tested on a real galvanic no-wait line of a primary aerospace international company; results show that the methodology application guarantees respect to the no-wait constraint and the minimisation of the production times, which concur to increase the demand satisfaction for the company.