Lead time selection and the behaviour of work flow in job shops

Few studies in job shop scheduling consider dynamic shop load and work flow issues. However, these issues are of importance to management responsible for shop floor control. This research investigates relevant internal performance measures and their relationship to external measures. As well, a new dispatching mechanism that seeks to even out the distribution of jobs in queue is investigated. Results show that a shop load balance index, which takes both shop load levels and load variability into account, has a very strong relationship to the lead times required to maintain a desired level of delivery performance. It appears that good performance based on internal measures is consistent with good performance based on external measures.