Sequencing Mixed-Model AssemblyLines to Minimize theNumber of Work Overload Situations

The mixed-model sequencing problem is to sequence different product models launched downan assembly line, so that work overload at the stations induced by direct succession of multiplelabor-intensive models is avoided. As a concept of clearing overload situations, especiallyapplied by Western automobile producers, a team of cross-trained utility workers stands by tosupport regular workforce. Existing research assumes that regular and utility worker assembleside-by-side in an overload situation, so that processing speed is doubled and the workpiececan be finished inside a station’s boundaries. However, in many real-world assembly lines theapplication of utility workers is organized completely different. Whenever it is foreseeable thata work overload will occur in a production cycle, a utility worker takes over to exclusively executework whereas the regular worker omits the respective cycle and starts processing at thesuccessive workpiece as soon as possible. The paper investigates this more realistic sequencingproblem and presents a binary linear program along with a complexity proof. Then, differentexact and heuristic solution procedures are introduced and tested. Additional experiments showthat the new model is preferable from an economic point of view whenever utility work causesconsiderable setup activities, e.g., walking to the respective station....