Quick Changeovers Cut Costs on Small Lot Orders

dhavas's picture

Ok, so you’re getting orders from your customers, but they’ve cut the quantities. So you are faced with smaller orders. Now the problem is that you have an increased number of changeovers to make these shipments. Long changeover and setup times kill productivity and increase costs especially when there are small lot sizes. There is a solution!

 Back in the ‘50s and ‘60s, Shigeo Shingo developed what has become known as the SMED System. SMED stands for Single Minute Exchange of Dies. Not every changeover can be done in 1 minute, but by using Shingo’s ideas, changeover times in many industries have been reduced from hours to a few minutes.

 Any changeover involves activities that can really be done while the machine operating. These are called External Setup (getting and prepping tooling or materials.) There are also things that must be done while the machine is out of production (installing tooling, materials, making adjustments and making setup runs.) These are called Internal Setup. Recognizing these differences and making the changes to separately perform the External and Internal Setup activities and then to streamline both of is the basic idea of SMED.

You can apply the ideas of SMED to your operations by following these four steps:

The First Step is to list all the activities that go into a changeover or setup. Then identify them as either External or Internal Setup activities.

The Second Step is to make sure that all the activities you called External Setup activities are all completed and ready to go before taking the machine out of production. These could involve …

• Gathering all the tooling and putting it next to the machine,

• Making sure that all the necessary fasteners and hand tools are available

• Making sure any equipment and tools needed for the changeover are available and ready to go.

• The Third Step involves investigating those activities you called Internal Setup activities to find ways to do as many of them as possible as External Setup activities. To make Internal Setup activities External Setup activities could involve …

• Figuring out how to set a dimension ahead of time instead of making adjustments in the machine,

• Performing all functional checks on the tooling to be installed ahead of time, or

• Pre-heating molds prior to installing in the machine.

• The Final Step is to streamline the External and Internal Setup activities to minimize the time required. In doing so you might …

• Store the tooling close to the machine and have it organized and ready to go as soon as the machine is available,

• Provide ways of easily moving heavy parts into position,

• Standardize the sizes and dimensions of setup parts to avoid changing heights of clamps on the machine,

• Provide jigs that position the new tooling immediately into the correct operating position,

• Use “One-Turn” clamps to eliminate the wasted time for screwing in a bolt, (Remember only the last turn does the holding!)

• Use Snap-in tooling,

• Redesign the tooling so that common parts of the tooling are not changed in a changeover,

• Redesign the tooling so that the use of hand or power tools is not required,

• Determine what setup activities can be done in parallel using more than one person,

• Eliminate steps that are shown to be un-necessary or undesirable such as test runs and finally

• Mechanize or automate so that the changeover can be done with the flip of a switch.

Experience has shown that the biggest problem in significantly reducing setup time is that most people do not believe that it is possible, “It’s always taken that long.” So start with one machine. Commit yourself to getting the time that the machine is out of production for a changeover down to 10 percent of what it takes now. With determination and creativity you’ll be surprised what you can achieve with very little out-of-pocket expense! Then do the same for another machine, and another, and another. Before long you will have reduced the changeover times on those machines where it hurts productivity the most.

Now you’re ready for those small lot orders, and, when the larger orders return, you’ll have lower costs and be more productive.