SMED – Single Minute Exchange of Dies
Known as “Single Minute Exchange of Dies” which is a lean term used to optimize the machine at hand. This process is intended to limit the amount of downtime a machine will have during a changeover.
Best described as a pit stop in professional racing, your goal as a pit crew is to ensure that the car gets back onto the track as efficiently and quickly as possible. The longer that machine is down the less profitable it is.
Video and photographs are taken during a changeover and a team is assembled to attack the situation and remove as many barriers as possible to minimize downtime.
Observation is also an important step in a SMED event because even the smallest obstacles can prevent a consistent changeover. The essence of the SMED event is to convert as much changeover time to be external and getting as much of the heavy lifting finished while the machine is running.
SMED is split in to two elements, internal and external. Internal elements are the actions and movements that occur while the machine is stopped. External elements occur while the machine is running. The objective of the SMED program is to move as much of the internal elements to external elements, and then streamline the remaining internal elements for high efficiency.
Some benefits to a successful SMED program include; lower manufacturing cost, smaller lot sizes, improved responses to customer demand (smaller lots enable more flexibility), lower inventory levels, and smooth startups.
Referring back to the “pit stop” in Nascar, the pit crew collects all the material needed before the car gets to them. This is the external process because the car is still racing. Once the car arrives at the pits the changeover takes about 20 seconds to change all four tires, fill up the tank, give the driver a sip of water, and repair any cosmetic issues. The whole process of putting the tire on the rims, filling up the big gas can, gluing the nuts on the rim, and buying the jacks takes several hours but that has become external because the racecar only feels that 20 seconds in the pits during the race.