The influence of material handling operations on the schedule makespan in manufacturing cell environments

In manufacturing environments, material handling is one of the processes that needs to be performed in order to move materials and products from one machine to another. The complexity associated with manufacturing scheduling problems, including material handling scheduling, has been intensively studied in the last several decades, so now it is widely accepted that most practical real-world scheduling problems cannot be solved optimally in reasonable time due to the combinatorial explosiveness associated with most of them. This paper considers the influence of material handling operations on the schedule makespan in manufacturing scheduling environments. Four types of lower bounds on the schedule makespan and potential delays introduced into the schedule when considering material handling operations are described. Evaluating the results obtained by calculating lower bounds and taking in consideration the potential delays can lead to improved solutions and a better utilization of the resources.