Creating Flow is one of the fundamental principles of Lean thinking, disruptions to Flow often come as a result of a product changeover which not only halt production for the changeover process, but often drive large batch sizes. This in turn can promote high levels of work in progress (WIP) and finished goods which occupy excessive amounts of hard cash.
In the spirit of continuous improvement, what an achievement it would be to reduce the changeovers to less than an hour! Hence adopt the approach of Single Hour Exchange of Die (SHED), What a difference a word made!