Theoretical and experimental analysis of operation lead times based on the IMPOS approach

IMPOS is an integrated material planning and operations scheduling methodology for discrete manufacturing systems. Details of IMPOS have been reported elsewhere; this paper emphasises the mathematical analysis of the operation lead times in IMPOS with some experimental results. It has been proven that the operation lead time is a variable parameter depending on the schedule as well as availability of resources. The calculated lead time of an operation is usually greater than its required lead time had it been the only operation scheduled. Two parameters of an operation which affect the deviations between these two lead times are the total times that the processing on the batch has been paused during the main and surplus processes (i.e. idle times).