Integrating buffer “stock” and buffer loops in an assembly line with conveyors: An automotive case study

The degree of automation in manufacturing systems, along with the characteristics of job handling and transport between workstations, and the product cycle time, determine the most suitable job handling system for each line. Conveyor systems allow for the management of re-entrant flows at the same workstations and more flexible system architecture through carousels, which also serve as a buffer loop to accommodate jobs awaiting machine availability. This paper explores the role of buffer stocks and blocking after service mechanisms, task allocation within the system, and operational characteristics to tackle the assembly line balancing problem in a fully automated assembly line interconnected by conveyors through discrete event simulation. Scenario analysis is employed to assess the impacts of constraining job flows through the conveyors on: fluctuations in throughput from shift to shift, its variability, and the critical WIP threshold for the CONWIP logic.