SMED

SMED, or Single-Minute Exchange of Die, is a lean manufacturing methodology aimed at reducing the time required to changeover a machine or process from producing one item to another. The objective is to shorten setup times to single-digit minutes, thereby enabling smaller batch sizes, reduced production lot sizes, and greater flexibility in responding to demand without sacrificing throughput.

SMED was developed by Shigeo Shingo as part of the Toyota Production System in the 1950s and 1960s. It formalizes a systematic approach to analyze and restructure changeovers to eliminate non-value-added activities.

Its core concept distinguishes between internal setup, which must be performed while the machine is stopped, and external setup, which can be prepared while the machine runs. The SMED methodology seeks to separate, convert, and streamline these activities, with an emphasis on converting internal steps to external whenever possible, optimizing tools and fixtures, standardizing work, and preparing for future improvements.

Typical steps include documenting all changeover tasks, separating external from internal tasks, converting as many tasks as possible to external, streamlining the remaining internal steps, and providing pre-setup materials and standardized setups. Tools used include standardized tooling, quick-change devices, pre-staging of parts, and parallel handling of tasks.

Benefits include shorter downtime, higher equipment utilization, faster response to design changes, and reduced inventory. Limitations include the need for stable process families, redesign of fixtures and tools, and ongoing training and monitoring to sustain gains.