The SMED technology lies at the heart of improved mechanical flexibil- ity and improved routine maintenance. It was first described in the book, A Revolution in Manufacturing: The SMED System, by Shigeo Shingo (Productivity Press) in 1985. I got my first copy shortly thereafter and immediately fell in love with it. Since then I have routinely bought cop- ies of Shingo’s book by the case and handed them out to colleagues who I believed could put the concepts to good use. I encourage you to get a copy and put it to good use.
Because SMED is an acronym for “single minute exchange of dies,” my colleagues often remind me that in the liquid process industries, we do not have dies. Of course, we do. Densification of polymer granules (discussed later) uses pelletizing dies that have a function very similar to the forming dies used in the industries that originally gave SMED its name. That said, successful use of SMED in the process industries requires some transla- tion in both language and practice and we will do that here.
case study: reduce maintenance time with smed
We first introduced SMED at Suncor in the mine maintenance team that pro- vides routine service for our heavy haul trucks. In their initial use of SMED, they reduced the time required for an oil change on a 400-ton truck from 83 minutes to 8 minutes. In their second use, they reduced the time required to change a truck engine from 250 clock hours to less than 45 hours. With those two experiences as a good start, within the past 8 months the mine maintenance team has improved truck availability by more than 55% (rela- tive) from prior levels. As described in some detail later, our experience in replacing heat exchanger bundles as well as many other opportunities for improving process equipment has been similarly rewarding.
In this chapter, a continuing series of examples is based on a plastic extruder at the Exxon Mobil Baytown chemical plant. To begin, the fol- lowing case study is a brief introduction to that operation.
case study: reduce manufacturing time with smed
Most manufacturers who produce plastic products feed their extruders and injection molding machines with dense plastic pellets because the pel- lets are convenient to handle and are easily fed into processing machines. However, plastic, as it emerges from the polymerization reactors, is usu- ally in the form of low-density crystalline granules. In the plants that pro- duce polymers, those granules are “finished” by using very large extruding machines to make the crystals denser and turn them into the pellets that are used by our customers.
Because pelletizing is the final manufacturing step before the product reaches the customer, it is also the step used to introduce customer-specific additives or modifiers to enhance or distinguish the product. Changing an additive often requires physical modification of the extruder or the support equipment, which can be a modest change such as switching the mate- rial in the additive feeder or a much larger change like reconfiguring the extruder barrel from plugged operation to vented operation.
Because the plastic cannot stop in the hot extruder, in the past, the reconfiguration required that we terminate production, purge all the mate- rial from the extruder, cool the machine, reconfigure the equipment, reheat the machine, and restart production. Often this activity required more than 15 hours of elapsed time from the moment that production stopped until the time that production resumed.
Using SMED, we reduced the actual work time required to execute the mechanical reconfiguration to just a few minutes. With such rapid execu- tion of the work, we can benefit from the persistence of the material as it flows through the machine, so we can now reconfigure the extruder while it remains in relatively normal operation. Today, we routinely run continu- ously throughout this mechanical conversion with only a very small loss (less than 100 pounds) of transition product at the interface that occurs when we engage the new additive.
Key idea: A good result in mechanical production is to reduce the
manufacturing time lost during equipment reconfiguration from 4 hours to 10 minutes. A good result in process manufacturing is to reduce the production loss from 15 hours to effectively zero. Because of considerations unique to the process industries, our initial problem with flexibility is much greater than it is for a mechanical manufacturer, but our opportunity for improvement is also much greater.
As you will see, in reconfiguring this extruder, we are essentially per- forming the mechanical operation of exchanging one part for another.
Although in this case the work is done to increase flexibility, the lessons from this example also describe the practice of improving availability by increasing the speed of routine maintenance.
what we can learn from nascar
It is useful to begin the discussion of SMED with an analogy to a situa- tion that is common to everyone: a flat tire. If you go to the parking lot and find that your car has a flat tire, you know that you are about to lose a half hour or perhaps more. By the time you resign yourself to the situ- ation, get out the spare tire, figure out how the jack works, get out the manual to identify where the jack attaches to the car, and find the tools, you might lose 10 minutes or more before you begin working on the tire itself. Unusual complications aside, it takes about 30 minutes to change a tire.
Yet we know that every Sunday afternoon we can turn on the television and watch the professional NASCAR pit crews change four tires and fill the car with fuel—all in 12 seconds. What are the characteristics of race cars and their pit crews that make this dramatic difference in performance possible? More importantly, can you duplicate or adapt those characteris- tics for your purposes? The answer to these questions is that racing teams have configured their equipment and their work to “keep the cars on the track”; by using SMED, you can also configure your equipment and work to keep your plant in service.
Actually, the differences between NASCAR pit crews and the mainte- nance teams in your plant are not as great as you might think. Professional pit crews have three primary advantages that the stranded motorist, an amateur, does not: preparation, teamwork, and equipment. Because we are professionals at our work (operating process plants), we should be able to adapt their professional advantages for our use. As you will see, these NASCAR practices are essentially the same as SMED practices:
1. Preparation: NASCAR teams are fully prepared. All the tools, equip- ment, and parts that they need are staged at hand ready for the event. They also have contingency tools and materials staged at hand in the event that some part of their preparation is imperfect or something unexpected occurs.
2. Teamwork and practice: NASCAR teams have several people, all of whom are well practiced at working as a team. In that way, they can
effectively perform the separate elements of the job simultaneously as opposed to having a single person doing each task in sequence. 3. Equipment: NASCAR teams recognize the value of reconfiguring
their equipment faster than the competition does, so they have spent the time and money needed to modify the vehicle, the wheels, the team, and the tools or equipment to make the task easy and fast. The third element contains an essential concept. NASCAR teams have recognized the value of keeping their equipment in service. Although I stopped tracking this statistic some time ago, for a long period, the Indianapolis 500 race was not won by the team with the fastest car on the track; it was won during the pit stops. That is, the total margin of victory in the race was less than the marginal time difference in servicing the cars.
case study: the value of keeping the cars on the track
In 2008, Ryan Newman won the Daytona 500 by a margin of only 0.092 seconds. During an interview that appeared in the May 9, 2008, edition of the Wall Street Journal, Mr. Newman’s chief tire carrier said, “You can’t win a race with a 12-second stop, but you can lose it with an 18-second stop.” Pretty much the same is true for process manufacturers.
Key idea: Rapid execution of mechanical work alone will not make us
successful, but poor execution can make us unsuccessful.
translating nascar success to our Plants
Let us look quickly at the details of each of the NASCAR advantages, which should help you see the industrial applications of this technology in your business.
Preparation
Not surprisingly, simply being prepared to do work has enormous advan- tages. Part of that preparation is establishing close coordination so that the crew is ready to work at the first moment at which the equipment stops. Part of that preparation is organizing the work and the workplace by hav- ing the appropriate support equipment, parts, and tools standing by. While
the race car is stopped, no activity occurs that is not absolutely and imme- diately related to and necessary for returning it to operation. Every other activity is done either before the car stops or after the car restarts. We can adopt the same intense focus when the equipment stops in our plants.
Key idea: Preparation activities do not cost more when done prior to
stopping production. Often they cost less because they can be done in a more orderly manner. The only important difference between prepar- ing for the work before it starts and preparing after it has started is that the plant continues to earn money during the period of preparation.
case study: make gains by Paying attention
Suncor’s first major increment of SMED improvement—the first 100-clock hour reduction in the time required for changing an engine—occurred before we began truly to practice the disciplined technology of SMED. While we were gathering the details of the work in order to perform the SMED analysis (described later), we changed an engine in half the prior elapsed time. It happened because during this event everyone was paying attention to the work. Until then, unlike the NASCAR teams, our mechan- ics had not yet recognized the value of keeping the truck in the mine, or at least they had not yet applied that value to their work.
There is no reason why we in the process industries could not experi- ence a NASCAR level of preparation for every event where we need to reconfigure our equipment and for all of the maintenance events that stop production.
Key idea: As with the Suncor trucks, you can likely receive an immedi-
ate incremental improvement from that type of focus simply by making the inherent value of routine work more apparent and by giving your teams the opportunity to respond to that value proposition. Remember that the quote earlier on the value of the pit stop did not come from the driver or even from the crew chief. It came from a tire carrier.
The principal difficulty in promptly achieving NASCAR-type prepara- tion in our plants is that the volume of detailed planning required to apply
this approach uniformly to all of our equipment exceeds the capabilities of our professional planning staff. For that reason, SMED is best applied as a frontline practice where people in small teams can plan and organize their work. Small teams in our plants have the same size and natural focus as the NASCAR crews. In teams of that size, people can plan and execute their work at a level of detail that can never be achieved by engineers or even professional planners.
Because it enables people throughout the business to achieve highly detailed improvements at a level of detail the engineering staff could not attempt, SMED is one of the great tools of autonomous improvement. There is essentially no risk in authorizing autonomous SMED practice because the value stream of the work and the work product are generally not changed. As you will see, the principal change is to eliminate waste from the execution of the work.
Note: Although SMED is thought of as a tool for deployment to the front-
line, if you have a need or an opportunity to do so, you can devote profes- sional staff to this work as soon as you complete this chapter. The success of that effort will be an important example to the rest of the organization.
case study: stage materials and reminding teams about Procedures
The maintenance manager at Exxon Chemical Baytown recognized an opportunity and created Exxon’s first SMED improvement less than 2 hours after his initial introduction to the technology. He applied SMED principles to the maintenance of a polymer “classifier deck,” which is used to con- trol the size of plastic pellets from the extruders by passing them through two screens of different mesh size (see Figure 4.1). Oversized pellets and clumps of polymer are rejected by the first screen while properly sized pel- lets and small pellets or crystalline fines pass through. The second screen identifies properly sized pellets to advance in the process while fines and small pellets are rejected by falling through.
The screens require changing periodically due to mechanical wear. We were able to reduce the total lost time for this task from 6 hours to 6 min- utes on the first attempt simply by aggregating the materials and tools in advance of stopping the unit and posting the instructions for the work as shown in Figure 4.2. Although the work of changing these screens is not complex and occurs about once each month, Exxon has five operating teams in order to provide coverage for the nonstop operation, so each team did the job relatively infrequently. As a result, team performance benefited
greatly from simply staging the materials and reminding the team how the work is done.
Teamwork
A very valuable lesson gained from examining the actions of pit crews as compared to amateurs changing their own tires is that pit crews always use more than a single person. They appear to have one person for every possible place where work can be performed without one team member
fIgure 4.2
Instructions for maintenance of classifier deck.
fIgure 4.1
Polymer classifier deck in operation.
interfering with another. It is also obvious that the teams have a plan for working together whereby each person’s individual work is always com- plementary to and coordinated with the other members’ work. No one is ever uncertain about who is doing what.
As with preparation, using several people to do the work reflects the recognition that the only important attribute of a pit stop is to get the car back on the track. Given sufficient time, a single person could do all the work, but that would not be the best way to do it if you intend to win the race. In the process industries, we need to come to that same understand- ing. In most situations, a team of several people will return our equipment to service more effectively than a single person could.
Although the emphasis in this discussion is on the speed of returning the equipment to operation, do not be fooled into believing that using sev- eral people for a task that could be done by only one person is necessarily an inefficient use of labor.
case study: reduce downtime with reduced work Hours
Exxon once owned a business that extruded plastic filaments and then wove that filament into an inexpensive fabric used, among other things, to wrap bales of cotton. As part of that weaving operation, workers periodically needed to add several hundred new spools of the filament to the “creel” that fed the weaving loom. Each spool needed to be joined to the loom by tying the starting ends of the new spools to the trailing ends of the old spools.
Originally, this task was assigned to a single person, and it regularly required a full 8 hours to accomplish. When we assigned a small team of five people to the same task, they completed it in less than a half hour. In addition to returning the equipment to operation more than 7 hours faster, only half the total amount of labor was required.
There were many reasons for this difference. Among them, for a sin- gle person working alone, the work was solitary, boring, and physically demanding due to long hours of repetitive motion. For a small team, it was a nice way to spend a half hour. For a single person, the 8 hours included rest breaks and breaks for personal needs as well as for lunch. During those breaks, the equipment was out of production and no one was working to return it to service. For a small team, which was able to start and finish the work in a short time, none of those interruptions occurred.
Equipment
Equipment is the thing most people think of first when they consider the differences between the professionals of NASCAR and the poor souls
standing beside their cars in the parking lot. Many professional racing cars do indeed have a value that far exceeds the cost of most personal cars, but the value is mostly associated with equipment that enhances perfor- mance on the track. Only a very small portion of that value is the result of the modifications that make it easier and faster to service the car. The cost of those modifications to enhance service is even smaller when considered in relation to the business value of keeping the race car on the track.
Exactly the same relationship is true in our plants. Although many SMED examples will be of the type shown in Figure 4.2, where there is little or no cost, there certainly will be times when you need to spend some money to get the SMED effect. More than half of the content of Shingo’s book is detailed descriptions of simple modifications that you can make that will allow your equipment to be serviced or reconfigured quickly and easily. In every case, the changes that Shingo describes are of the same sort as the modifications that pit crews adopt to make race cars easier to ser- vice. They are always small relative to the value of the equipment and very small relative to the value of keeping the equipment in operation.
Once again, engineers and managers can never hope to work at the level of detail needed to modify all the equipment in a plant for this purpose, but when you adopt SMED as a formal practice authorized for autono-