Reducing worker(s) by converting assembly line into a pure cell system

The line-cell conversion is established as a new production system towards converting traditional conveyor assembly line to a cell system, in which one (or multiple) worker carries out all of the operations of a job in a cell. Its performance improvement can be enhanced by reducing worker(s) without decreasing productivity. How to conduct this conversion by determining how many cells should be formatted and which workers are assigned in a cell, is a complicated decision problem. This paper presents a multi-objective line-cell conversion model with the two goals of reducing worker(s) and increasing productivity simultaneously, in a production environment that converts traditional conveyor assembly line into a pure cell system. We identify several mathematical insights on solution space of the multi-objective line-cell conversion model and prove that it is an NP-hard problem. Then we provide an improved exact algorithm to obtain Pareto-optimal solutions of the multi-objective model. Several numerical simulation experiments are performed to illustrate that the line-cell conversion can be used to reduce worker(s) and the total throughput time at the same time.