### Quick Set-ups (Single-Minute-Exchange-of-Dies - SMED)

• If a production process or work station is supposed to produce several different products there will typically be time and cost required to make the change-over.
• Setting up a machine or process is not a value-adding activity.
• Definition of Set-up Time for a machine, work-station or process: The time between production/processing of the last unit of one product/lot and when the first good unit of the next product/lot is produced.
• Other definitions
• Machine: A piece of equipment that is fundamental to the operation. It is typically the focus of the set-up. Set-up involves doing something to the machine so it can produce different items.
• Fixture: A device attached to a machine to adapt it for a particular use. This includes dies, nozzles, blades, drill bits, cutting heads, extensions, and guide bars.
• Tool: A device for installing fixtures and adjusting fixtures and machines, such as screw drivers, wrenches, and pliers.

• Typically we have addressed the large cost/time of set-ups by:
• Having specially trained set-up workers who are especially skilled at setting up equipment
• Problem: Other workers have to wait around until the set-up workers can set up for the next run
• Producing in large batches to minimize the number of set-ups
• Example: If set-up time is 8 hours and running time per unit is 1 minute then for a batch of 100 units the average time/cost is

[8(60 min.) + 100(1 min.)]/100 units = 5.80 min/unit

If we increase lot size to 10,000, the average time/cost is

[8(60 min) + 10000(1 min)]/10000 = 1.048 min/unit

This is an 82% reduction in per unit cost.

• BUT - the average cycling inventory is 100 times larger, and the cycle time between product runs is 20 times larger

• Combine or sequence products/jobs that are similar so the change-over between runs is simpler.
• This can be beneficial, but the risk is that it will cause late deliveries of other products. The sequencing of work is set by what product is currently running, rather than what is needed now. Similar to large lot size approach.

• We have generally treated setup time and cost as inherent to a process and not changeable. But:
• Small-Lot, Kanban scheduling requires that set-ups be performed quickly, because the number of set-ups is much larger than with large lot-sizes.
• To move closer to the ideal production system, we need to reduce set-up time. So Lean Production treats set-up time as changeable and improvable.
• If set-up time/cost can be reduced, the effect on optimal lot-size can be substantial. For example, if the set-up time in the earlier example is reduced from 8 hours to 10 minutes:

Then for a batch of 100 units the average time/cost is

[10 min. + 100(1 min.)]/100 units = 1.10 min/unit

If we increase lot size to 10,000, the average time/cost is

[10 min + 10000(1 min)]/10000 = 1.001 min/unit

Thus, the benefits from increasing lot sizes are small.

• Shigeo Shingo has developed some structured methods for reducing set-up time.

• Internal Versus External Set-up Activities
• In 1950, while working for Toyo Kogyo's Mazda plant, Shigeo Shingo began his systematic study of production set-ups.
• Stamping operation
• Worker looking for a bolt to make die change; while looking for correct bolt, the entire stamping operation is idle
• His "solution" of modifying a bolt from another machine was time-consuming, and created another set-up problem for the other machines

• Observations lead to the recognition that set-up activities can be classified as either "Internal" or "External"
• Internal set-up activities, such as mounting a die or changing the ink cartridge on a photocopier, are activities that can be performed only while the equipment or process is stopped.
• External setup activities, such as collecting all bolts needed to mount a die or unpackaging an ink cartridge from its carton, are those that can be done while the equipment is operating.
• By making sure external set-up activities were done while the process was operating Shingo cut set-up time more than in half.

• Changing Internal Set-up to External Set-up
• Shingo was observing a large side-planer used to machine diesel engine beds: much time was spent,"... centering and dimensioning the engine bed ... on the planar table itself."
• The planar had to be shut down while this was done, so it was treated as an internal set-up activity.
• By adding second table, this could be done as external set-up

• Procedure for Reducing Set-up Times (SMED)
• Reported cases: Toyota Motor Company bolt-making machine set-up reduced from 8 hours to 1 minute. Set-up for a boring machine at Mitsubishi Heavy Industries reduced from 24 hours to under 3 minutes!

• SMED follows a simple five step procedure:

1. Observe and analyze in detail how the set-up is currently performed.

3. Of the activities currently performed, separate internal set-up activities from external set-up activities, and perform external activities while the process is operating.

4. Wherever possible convert internal set-up activities to external.

5. Simplify and streamline all activities.

1. Observe and Analyze the Existing Process
• An essential feature of set-up time reduction is understanding how the set-up is currently being performed.
• Create activity charts, worker-machine charts, and set-up work-sheets
• Worker-machine chart tracks what worker(s) and machine/process are doing simultaneously. Can see whether machine idleness is being created by poor sequencing of worker's activities
• Videotape set-ups
• Invaluable in showing workers what they are currently doing and how the set-up can be improved.

2. Evaluate Each Task and Try to Eliminate as Many as Possible
• Using the activity charts and worker-machine charts and set-up worksheet, analyze each task that is performed. Try to eliminate as many tasks as possible using a five why's or value/process analysis approach (e.g., why is this task being done? What does it contribute to the set-up? Could it be done as part of another task?).
• This evaluation/elimination is repeated during each of the following steps

3. Separate Internal Set-up Activities from External Activities and Perform External Activities while the Process/Machine is Operating

• Many set-up tasks that are performed while production is stopped are really external activities that could easily be performed while the machine/process is operating.
• Make sure all external set-up activities are performed while the process is operating, either perform external activities for a set-up while production on the previous job/batch is occurring or after production of the new product/batch has begun (e.g., replacing materials in storage).
• Suggestions
• Make a written set-up plan that sequences when each of the activities are to be performed. Clearly highlight the external activities.
• The plan should list any parts, tools, and fixtures needed, and any numerical values of any settings or dimensions for the machines or fixtures.
• Make a checklist of all the items (parts, fixtures, tools) needed for each set-up/changeover. Then create a "part-holder" box (or set-up kit) that will hold the parts and tools needed, with the list attached, so the worker can check off parts as she gathers them before the set-up.

• Prepare and test parts and tools, transport parts and tools to the machine, bring necessary materials to the machine and transport materials removed from the machine as external activities
• Test parts before stopping the process: One of the biggest wastes of set-up time results from not discovering a part needed for the set-up is defective until the internal set-up is being performed; by checking and testing parts during the external phase, these delays are eliminated.
• Store parts, fixtures, and tool so they are easy to find and easy to remove and replace. Store materials needed for a set-up as close together and near the machine as possible.

• Improve the coordination of material transport so materials are moved while machines are running. Let machine operators transport their own materials.
• Moving and pre-positioning materials as an external activity may involve more total work than transporting materials as part of the internal set-up activities, but if it converts internal to external work then there may still be a net improvement in productivity.

• Activities that appear to be internal activities can sometimes be converted to external activities by changing work methods, adding work aids, adding extra tables, vats, or containers, preheating or precooling, materials, or using container liners.
• Heating/Cooling of molds or heating/cooling/mixing of fluids
• Rather than doing all of the heating/cooling or mixing of materials as part of the internal set-up, which is common, preheating or precooling of materials can often be done external to the set-up so that final heating/cooling during the internal set-up phase requires less time. Frequently waste heat from other operations can be used to do this which results in an energy saving as well.
• Cleaning activities
• Have two or more sets of tools or processing vessels; the dirty or contaminated ones can be replaced with clean ones quickly during internal set-up, and then the dirty ones can be cleaned after production has restarted. For fluid vessel cleaning, rather than having two separate vessels, a lower cost solution is often to use plastic vessel liners which can quickly be exchanged.

5. Simplify and Streamline Activities

• The primary focus should be on reducing the time to perform internal set-up activities because this will reduce production system idleness.
• The best way to reduce set-up activity times is by task simplification and task elimination.
• Suggestions

1. External set-ups time can be reduced through better tool and material storage and transport.

• Have tools stored neatly in racks
• Each worker/work-station could have its own tools
• Each worker/work-station could have its own transport device

2. Dies and other parts that must be changed during set-ups should be standardized in size and shape.

• Dies or tools can be inserted and removed like "cassettes" in a cassette player without having the calibrate and align the die or tool.

3. Use the same standard components and fasteners for each set-up
• This way the fasteners stay with the machine, and they simply have to be loosened and re-tightened for each set-up, rather than removed, replaced, transported and stored.
• Ideally use only one type of fastener (e.g. bolts) so only one tool is needed and fasteners cannot be mixed up.

4. Use fasteners that can be loosened and tightened with a single turn, rather than those that require turning the fastener several revolutions. Use fasteners and attachments that can be installed with a single tool.

5. Reduce or eliminate adjustments by using fixed settings and markings on dies, tables, and guide bars. Every set-up can be pre-marked so that tools and dies do not have to be measured each time; the "mark-points" on the dies and tools simply have to be matched with those on a table or guide bar.

6. Have two or more workers doing the internal set-up in parallel. For example, if adjustments have to be made by going back and forth between the front and back of a machine, the walking can be eliminated by having two workers do this.

• Generalization of SMED Techniques
• Can be used for any changeover, including changing a printer cartridge in a printer or a worn blade or drill bit in a machine), for performing many maintenance and repair jobs, or for changing from serving one customer to another customer in a service system.
• Benefits of Quick Set-ups
• Quick set-up methods result in simpler, more structured set-up procedures. This produces many benefits other than the obvious cost benefits.
• Cost
• Can make products in smaller batches, which reduces WIP and finished product inventories.
• Simpler set-ups require less skilled workers (operators can do set-ups instead of set-up specialists). Production workers are not left idle while set-up specialists do the set-up. Set-up specialists can focus on the more difficult set-ups.
• Simpler, structured set-ups usually produce less start-up scrap

• Quality
• Simpler, structured set-ups result in fewer mistakes that can cause defects. Trial-and-error adjustments are eliminated.
• Production Flexibility
• Can switch among products more quicker to adjust to changes in demand mix
• Capacity
• Quicker set-ups effectively create additional capacity at no cost; eliminates need for more equipment, workers, and overtime