SMED (Single-Minute Exchange of Die) is Shigeo Shingo's method for radically reducing changeover time. The core move is separating internal setup (which must be done while the machine is stopped) from external setup (which can be done while it runs), then converting as much internal to external as possible.
Fast changeovers make small batches economical, unlocking flow, leveling, and responsiveness. SMED directly improves the availability component of OEE.