Mixed-model sequencing to minimize utility work and the risk of conveyor stoppage

This paper investigates the problem of sequencing N products on an assembly line with two objectives: minimizing (1) the risk of conveyor stoppage and (2) the total utility work. For a single station with arbitrary processing times, this problem is proved NP-hard in the strong sense for each of the two objectives. For a single station with two product types, each of which has a constant processing time, a sequence minimizing both objectives can be found in O(logN) computation time.