Designing a mixed-model assembly line to minimize the costs of idle and utility times

A mixed-model assembly line with either closed or open stations is considered in this research. The problem is to minimize the total cost of the utility time and idle time incurred due to different line parameters (launch interval, station length, starting point of work, upstream walk, locus of the operator’s movement, etc.) and operation sequences of the mixed models. Two models for both closed-station and open-station systems are developed to determine line parameters optimally. The models are tested with a three-station mixed-model line in which the station type is assumed either closed or open. This research shows that a set of line parameters are available for which the total cost of utility and idle times is minimal. Results indicate that the minimum total cost of utility and idle times in an open-station system is less than that in a closed-station system for a given line length. Other results pertinent to the line design are also demonstrated.