Scheduling using drum-buffer-rope in a remanufacturing environment

Scheduling in a remanufacturing environment is more complex and the scheduler must deal with more uncertainty than in a traditional manufacturing environment. In order to properly schedule in a remanufacturing environment the schedule must be able to cope with several complicating factors which increase variability. The schedule must be able to cope with conditional routeings, a routeing that may or may not be taken due to the condition of the unit. The schedule must also be able to cope with dependent events, e.g. operation B cannot begin until operation A is completed. Drum-buffer-rope (DBR) offers an extremely robust method of scheduling. A schedule built using DBR can take both conditional routeings and dependent events into account. A realistic example from a military depot is discussed in detail and each step required to build a schedule using DBR is explained fully. This paper also shows the results from a simulation model of DBR at a repair/rework depot which are benchmarked against the present production planning and control system.