Repetitive lots: The use of a sequence-dependent set-up time scheduling procedure in group technology and traditional shops

This study investigated a procedure designed to improve performance in group technology shops. The repetitive lots (RL) scheduling procedure capitalizes on the sequence dependency of set-up times in shops. This procedure scans a queue of waiting jobs, seeking to find a job identical to the job that was just processed on a machine, which should eliminate the need for a machine setup. The truncated repetitive lots (TRL) procedure prevents lots from becoming excessively large by allowing no more than K jobs to be combined. In this study, K was set at five. Computer simulation was used to compare a shop configured as a group technology shop with the same shop configured as a traditional job shop and as a hybrid, which combined features of both group technology and traditional job shops. The use of RL scheduling procedures clearly led to an improvement over first-come, first-served performance by all shops. This improvement was greatest in the group technology shops (those with dedicated machines).