Last update: January 16th, 2011 - Part 1
For manufacturers, lot size reduction and reactivity are mandatory to swiftly respond to market demand. Mastering SMED quick changeover technique is a key to success.
The business paradigm of the 21st century is made of increased requests for customized products available in short time, at low price. For manufacturers, this means reduced life cycles and reduced lead times. Serving off the shelf is scarcely a good option, as the carry over costs and risk related to inventories are too high.
For manufacturers, the solution is in batch size reduction and flexibility. Though mastering quick changeovers is a must.
Most often, the changeover happens like the time chart below shows. It starts when the last part from actual production batch is finished and ends when the first part from new production batch is ready to be processed at normal pace.
Breakdown of Changeover duration
The machine is usually stopped and all changeover operations happen in sequence, while the machine is stopped. The machine will start again only after completion of adjustments and trials, perhaps after quality check and when the appointed staff gives its ok.
Most often all these operations are done without any standard method nor procedures or checklists. This means the changeover sequence, and hence its duration is related to individual know-how, skills and habits. A sin in the times where 6 sigma fights causes of variability!
Teamwork, meaning several operators sharing changeover operations in order to minimize the stop time is also scarce. As changeovers take time, cause productivity loss and carry costs, the temptation is to dilute them in changing less often by launching bigger batches. This leads to adopt so-called Economic Order Quantity to define the batch sizes.
The EOQ policy ends up with higher inventories and lower agility, which are opposite of what is required in the new paradigm.