SMED is a structured approach to reducing changeover durations. Here are 4 good reasons to consider deploying SMED.
1. More production capacity is required
A critical resource of the production process is not able to deliver the expected quantity, due to lack of capacity. Such a resource is usually called a bottleneck, and chances are that a quick analysis will show that changeover durations are one of the major factors of capacity wastage.
Rather than reducing the number of changes and extending the series, it’s better to work on reducing the duration of changeovers from one series to the next in order to recover wasted capacity.
In many cases the gains through the application of the SMED method are sufficient to recover the lacking capacity. If it’s not the case, it is then necessary to check the distribution of the causes of capacity wastage (via a Pareto diagram, for example). Machine downtime due to breakdowns or quality issues discarding a part of the production may be additional themes to deal with.
2. More flexibility is required
When production capacity is sufficient but there is a need to better stick to the demand, this can be achieved by changing the productions more frequently.
Indeed, for a customer waiting for a given product, the waiting time is function of the length of the queue of orders to process before launching the production of the expected product, the lead time of the production process itself, and finally the shipment process.
The reduction of the batch sizes and the multiplication of launches help reducing the global lead time. For this solution to be viable, however, it is necessary that the multiplication of changeovers does not cause the production capacity to fall below the required level, otherwise we find ourselves in the previous case.
To prevent this risk, the duration of the changes can be reduced by applying the SMED method and converting the time gained into additional changeovers.
3. More machine availability is required
In this third case there is no shortage of production capacity nor lack of flexibility but what is lacking is time during which a machine is available for periodic maintenance operations, or for processing exceptional additional orders.
In this case also the reduction of the duration of changeovers may be a solution to consider. The recovered machine availability may then be used as needed.
4. Freeing time of experts
This case is rare, but may arise, especially in environments that are strongly constrained by standards or regulations and in which changeovers require the assistance of personnel with special qualification and/or authorization. In these cases it is no longer the capacity or the availability of the production means which is limited but those of these “experts”.
They may be required simultaneously for different changeovers and their limited availability may adversely affect the overall performance of production, with some machines, equipment or lines waiting.
Take care of adjustments and tests too
The term “changeover” is sometimes interpreted as the change of dies, or the change of settings only. A changeover should include the clearance of everything related to the completed series and the resuming of production with the new series, new reference or new batch, at nominal speed. This means that all required adjustments and tests have been performed and their durations have been counted as part of the changeover.
Excluding these durations in order to pretend to change over quickly may leave them out of the scope of improvements, which is a loss of improvement opportunity and only a partial application of SMED.