Single Minute Exchange of Die (SMED)

One of the unfortunate characteristics of manufacturing is waste. From unused raw materials to faulty or damaged products, waste can end up costing a company quite a bit in financial loss. To reduce waste, there are a number of different strategies companies can use. One of the more popular strategies is Single Minute Exchange of Die (or SMED).

What Is SMED?

One of the drawbacks to manufacturing is set-up time for a production run. SMED is a method that allows set-up operations to be performed in less than ten minutes. In other words, set-up operations should be completed in a number of minutes that is represented by a single digit: one minute to nine minutes.

This practice helps cut back on waste and time spent between each production runs. By using the SMED method along with other quick changeover practices, it reduced the amount of time spent to change out the machines in a production line from one product to the next. SMED also helps reduce the size of production lots and inventory because there is less waste, thus improving overall production flow.

History of SMED

single-minute-exchange-die

The concept of SMED was originally adopted and used in Japan during the 1950’s. The methods were later implemented in West Germany in 1974 and then the rest of Europe and the U.S in 1976. SMED finally gained worldwide acceptance during the 1980’s.

During its origins in Japan, SMED was adopted for Toyota. Toyota needed additional space to store its manufactured cars. Because Japan is a small series of island, real estate is expensive. Because Toyota had to store their cars in high-priced lots, the company’s profits were less than other manufacturers.

Toyota could do nothing about the costs of land but an engineer named Mr. Shingo decided that if the change-over costs could be reduced, the company would realize higher profits. Normally, the cost of change-over on production machines was offset by the volume of product the machines could produce before they were changed. So the cost of change-over was faily low. But the costs for lot storage was exceeding what the company was saving.

It took several yuears but Toyota managed to come up with a system that minimized the tools and steps sued in the manufacturing process. Also, by maximizing their existing components so that more cars shared the same components, the company managed to cut back on costs and to speed up change-over time.

How Does SMED Work?

In the manufacturing process, when the last item in a production run has been completed the equipment and machinery is shut down, cleaned, and new tooling is added and changed. This gets the equipment ready for the next run on a new item. This change-over can involve a number of small to large adjustments, resupply of raw materials, and system checks before the machines are started up again. Even after the machines have been started and materials used, operators may need to continue their adjustments to produce an item that meets the desired requirements.

The time spent during change-over costs the company money as there are no finished items being produced. Also, the equipment produces waste as adjustments are made after the machine starts up the new production. All of this can be reduced using SMED.

There are two types of set-up using SMED: external and internal. External Setup is procedures that are done while the machines are still operating and before they are stopped for the change-over. Internal Setup is procedures that occur only after the machines have been stopped for change-over.

SMED uses a number of different steps that improve production and cuts back on waste. These steps help to separate the changeover process into several key components. The steps are:

  1. Eliminating non-essential set-up procedures. This includes anything that is not necessary for the production of the new line of items.
  2. Get all external parts ready for set-up. This includes making sure there is plenty of raw materials, gathering up required tools and parts, and having everything on hand before the machines shut down.
  3. Simplify Internal Set-up – Use pins, cams, and jigs to reduce adjustments, replace nuts and bolts with hand knobs, levers and toggle clamps… remember that no matter how long the screw or bolt only the last turn tightens it.
  4. Make sure that all measurements are accurate. Having incorrect measurements can lead to longer change-over times and can increase waste.

Benefits of SMED

Proper implementing of SMED can reap several benefits for a company. The most common are the reduction of downtime because of the changeover process and the reduction of waste that is inevitably created during startup. Some additional benefits include:

  • Less time spent on production.
  • Machines have an increase in work rates. This means you actually get more work out of the equipment.
  • Productivity sees an increase.
  • Reduction in errors during set-up and after the machines starts back up. Less defects are produced.
  • Inventory costs are minimalized due to less raw material needed. Also saves on space for storage.
  • Level of safety is increased due to following proper change-up procedures.
  • Less time spent cleaning up after production due to better organization.
  • Overall costs of set-up are lower due to less time spent during change-over and less waste.
  • Operation of equipment takes less skill and training due to simplified process.
  • Deterioration of stock is kept to a minimum.
  • Lot size reduction
  • Reduction in finished goods inventory
  • Profits are increased without having to spend more money on more equipment.