SMED summary

Revolution in Manufacturing: Single-minute Exchange of Die System

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“The slower but consistent tortoise causes less waste and is much more desirable than the speedy hare that races ahead and then stops occasionally to doze. The Toyota Production System can be realized only when all the workers become tortoises.

- Ohno, 1988 -

From Wikipedia:

Single Minute Exchange of Die (SMED) is one of the many lean production methods for reducing waste in a manufacturing process. It provides a rapid and efficient way of converting a manufacturing process from running the current product to running the next product. It is also often referred to as Quick Changeover (QCO). It is a concept that says all changeovers (and startups) can and should take less than 10 minutes … hence the phrase Single Minute. Closely associated is an advanced concept of One-Touch Exchange of Die, (OTED), which says changeovers can and should take less than 100 seconds.

For best results, SMED techniques should only be targeted at bottleneck areas within the process.

• Firstly ensure that 5S action has been taken beforehand to improve working area layout and tool accessibility and eliminate wasteful changeover movements.
• Next, identify and separate internal set-up activities (An internal activity is one that can only be done with the machine stopped, an external activity is anything that can be done before or after the set up without stopping the machine) from external set-up activities.
• Identify whether any of the internal set up operations could be performed as external operations i.e. outside the cycle time of the machine. e.g. moulds normally preheated on the machine itself could be preheated in advance in a small off-line oven.
• Finally, re-design tooling or changeover equipment fixtures for quick release and insertion/removal, incorporating caddies or tool carriers for off-line set up.
• If changeover procedures are not already standardised, a procedures or operations manual should be created and then developed to incorporate subsequent improvements in the changeover methods used.

Attaining Quick Changeovers are a critical prerequisite for Heijunka - a Japanese term that refers to a system of production smoothing designed to achieve a more even and consistent flow of work.

In summary:

• Eliminate: The first thing I look for is elements that can be eliminated. There is no point in improving something that should not be done at all…
• Externalize: All elements that can be done prior to line shut down should be done ahead of time or “externally” to the changeover time.
• Simplify: Once all possible elements have been eliminated and externalized, it is time to begin improving the remaining elements. Simplification covers two major areas:
• Measurability: If the machine is adjusted correctly at the beginning, no fine tuning after restart will be necessary. If possible, adjustments should be eliminated. If this is not feasible, adjustments need to be measurable and repeatable.
• Tool elimination: For example, the replacement of nuts and bolts with handknobs and levers. Other useful devices are toggle clamps, pins and cams.

People who are to do the changeover should be thoroughly trained in what they are to do and when. They must also be trained in what they are not to do.

Quick Changeover and SMED can be applied to transactional processes as well or non-manufacturing processes.