Finite capacity scheduling using a predetermined placement sequence

This paper presents a new heuristic for the finite capacity scheduling of factories. It treats the task of scheduling a factory the same as scheduling a large project that has many delivery points. The job placement sequence on machines is used as a link between infinite capacity schedules and finite capacity schedules. An ideal placement sequence is proposed from the infinite capacity backward schedule and this is embedded into the project network for finite capacity scheduling. This allows a finite capacity algorithm whose boundary condition is the most tightly packed schedule possible, and is also ideal from a cash flow perspective. The paper proposes a preference list of machines as an integral part of the scheduling process and shows how to switch between machines using preferences. It also shows how to integrate infinite and finite capacity schedules within the same algorithm by using a parameter called the constraint horizon. The heuristic is explained using input–output matrices and by working through an example of a project network. The example includes a discussion of circuits and a detailed explanation of how to implement the heuristic in a computer program.