SMED
SMED
"Single Minute Exchange of Dies"
Lean thinking has targeted setup and changeover times for many years, SMED is an idea and tool that helps reduce your setup and tooling times. Setup and change over times are not the same. Setup is the time to change the tooling and parts from one production run to another, Change Over is the time from the completion of one product run to the next product run achieving full effective output. Setup and change over times are one of the seven major losses identified by the Lean Manufacturing Principles .
Set-up time refers to the time taken to physically make the changes to the line in order to run the new product. Changeover reduction simply refers to attempts to reduce the time taken to carry out the changeover process.
There are a many benefits in targeting change over time:
1. Increased machine efficiency
2. Reduced stock requirement.
3. Increased availability and capacity.
4. Reduced work in progress.
5. Increased flexibility.
When putting putting projects for change over reductions many people have heard of “SMED” (Single Minute Exchange of Dies). This approach was first put forward in a book by Shigeo Shingo in 1985 called “A revolution in manufacturing: the SMED system”.
Shigeo did not claim that all changeovers should be done in one minute but rather they should not take longer than 10 minutes i.e. minutes measured in single figures. He defined methods to achieve this as listed below:
Measure
Measure the current changeover times and record them in order to monitor improvement (Often simply measuring the changeover time can improve things.). This can be achieved using simple manual entry operations or via an automated solution.
Separate “External” and “Internal” activities
“External” activities are jobs and operations that can be carried out while the machine is running (e.g. fetching new tooling and tools required for changeover).
“Internal” activities are those jobs which cannot be carried out while the line is running (e.g. changing moulds). By separating the two activities it is intended that as much as possible is carried while the line is running in preparation of the next product changeover. The number of operations to be carried should be minimised to further improve change over times
Convert “Internal” to “External” activities
By looking at the internal task carefully it is often possible to convert some of the internal tasks to external ones.
Reduce the time to carry out internal tasks
Of the operations left the efforts should be made to reduce the time taken to carry them out. This may require design or engineering changes: consider quick release fastenings, setting jigs, single head sizes of bolts etc..
When considering SMED and changeovers consider the following as well:
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Videoing the operations of changeover and let the operators and technicians review them to analyse the sequence of events.
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"Practice Makes perfect", Get the crews and teams to practice changeovers
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Changeovers may be far more productive with more personnel to carry out the operations.
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Target Bottleneck machines
Consider SMED as part of any Lean Manufacturing improvement activitie