Makespan minimization for a 2-stage assembly scheduling problem subject to component available time constraint

This paper considers a 2-stage assembly flowshop scheduling problem where each job is assembled with two types of components and makespan is the objective measure. For the assembly, one type of the components is outsourced subject to job-dependent lead time but the other type is fabricated in-house, at the first stage. The problem is shown to be NP-complete in the strong sense. Some solution properties are characterized, based on which three heuristic algorithms are derived. A branch-and-bound algorithm is also derived by use of the associated three lower bounds and several dominance properties. Numerical experiments are conducted to evaluate the performances of the proposed branch-and-bound and heuristic algorithms.