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. This rapid changeover is key to reducing production lot sizes and thereby improving flow (Mura). The phrase “single minute” does not mean that all changeover and startups should take only one minute, but that they should take less than 10 minutes (in other words, “single-digit minute”). Closely associated is a yet more difficult concept, One-Touch Exchange of Die, (OTED), which says changeover can and should take less than 100 seconds. A Die is a tool used in manufacturing. However SMED’s utility of is not limited to manufacturing
The concept arose in the late 1950s and early 1960s, when Shigeo Shingo was consulting to a variety of companies including Toyota, and was contemplating their inability to eliminate bottlenecks at car body-moulding presses. The bottlenecks were caused by long tool changeover times which drove up production lot sizes. The economic lot size is calculated from the ratio of actual production time and the ‘change-over’ time; the time taken to stop production of a product and start production of the same, or another, product. If change-over takes a long time then the lost production due to change-overs drives up the cost of the actual production itself. This can be seen from the table below where the change-over and processing time per unit are held constant whilst the lot size is changed. The Operation time is the unit processing time with the overhead of the change-over included. The Ratio is the percentage increase in effective operating time caused by the change-over. SMED is the key to manufacturing flexibility.
One redefinition of these wastes for service operations by Bicheno and Holweg (2009) is as follows:
1. Delay on the part of customers waiting for service, for delivery, in queues, for response, not arriving as promised. The customer’s time may seem free to the provider, but when she takes custom elsewhere the pain begins.
2. Duplication. Having to re-enter data, repeat details on forms, copy information across, answer queries from several sources within the same organisation.
3. Unnecessary Movement. Queuing several times, lack of one-stop, poor ergonomics in the service encounter.
4. Unclear communication, and the wastes of seeking clarification, confusion over product or service use, wasting time finding a location that may result in misuse or duplication.
5. Incorrect inventory. Being out-of-stock, unable to get exactly what was required, substitute products or services.
6. An opportunity lost to retain or win customers, a failure to establish rapport, ignoring customers, unfriendliness, and rudeness.
7. Errors in the service transaction, product defects in the product-service bundle, lost or damaged goods.
When a product or service has been perceived or appraised to fulfill a need or desire–as defined by the customer–the product or service may be said to have value or worth. Components of value may include quality, utility, functionality, capacity, aesthetics, timeliness or availability, price, etc.
All the activities (both value-added and non-value added) required within an organization to deliver a specific service; “everything that goes into” creating and delivering the “value” to the end-customer.
A visual representation of the sequential flow of a process. Used as a tool in problem solving, this technique makes opportunities for improvement.
Non Value Added (NVA) – Those process steps in a Value Stream that take time, resources or space, but do not transform or shape the product or service to meet the needs of the customer
Work required to change over a machine or process from one item or operation to the next item or operation; can be divided into two types:
1. Internal: set-up work that can be done only when the machine is not actively engaged in production OR
2. External: set-up work that can be done concurrently with the machine or process performing production duties
As used in manufacturing, the time from when the last “good” piece comes off of a machine until the first “good” piece of the next product is made on that machine. Includes warm up, first piece inspection and adjustments.
The place in the value stream that negatively affects throughput; as a resource capacity limitation, a bottleneck will not allow a system to meet the demand of the customer.
De-bottlenecking essentially involves studying the bottleneck in the system and Improving the throughput rate of the process by working on optimizing the utilization of the bottleneck.