Technology

5S example from Korry

Jul 9 2013

Visual management as a “tier 2” tool

In the TPS Principles and Practice discussion group on LinkedIn, Emmanuel Jallas asked whether visual management was a “lever to make other tools work, or  a tool by itself.”

Visual management as embedded into other tools

As I see it, visual management should be part of everything else we do, but not treated as a stand-alone topic. Visual management should be considered in the design of a plant, a production line, a supermarket, a shipping/receiving area, a crossdock, a cafeteria, a restroom, etc. It is part of setup time reduction, cell design, or kanban implementation. It make visual management a “tier 2” tool.

If, however, you try to discuss it or teach it as a stand-alone, generic subject, you quickly get dragged into what it involves in different, specific contexts. If you have a mixed group, whatever you say will only be of interest to a minority at a time. On the other hand, if you are teaching Lean Logistics, then the discussion of visual management in materials handling comes naturally.

If you write a “How to” guide, you really have to think who your intended readers are. If you write on how to design a machining cell, you know exactly who they are. And, if you do a good job of writing it, all of it will be of use to this audience.

But who is the audience for visual management? It’s everybody! But the general theory of visual management fits in a few pages. After that, you have to go to examples, and each example is for an application that is only of interest to a tiny sliver of a manufacturing organization. So maybe 1% of your How-to book is of interest to each reader, but you can’t cut any of it, because another reader’s 1% is somewhere in the  remaining 99%.

By the way, people like Gwendolyn Galsworth or Michel Greif, who have written several books on visual management obviously disagree with me on this. I use their books like dictionaries, not how-to guides.

Visual management and Potemkin villages

Since visual management is, … visible, it is commonly part of the Potemkin villages put up by companies that want to look lean to outsiders. But the fakery is easy to spot when, for example, you see bins under a sign that says the area should be clear, the operators don’t know what the colors on the andon lights mean, the color codes are inconsistent across the floor, or a production monitor shows overproduction and production continues,… It does not take many discrepancies to torpedo the credibility of visual management.

Complicated color codes are a tell-tale sign that a system is not used.  The andon lights I have seen in Japan have only three colors with one and only one solidly lit at a time. It’s Red, Yellow, and Green, with Red meaning that the machine is stopped, Yellow that it is available, and Green that it is working. Used consistently throughout a shop floor, it gives you an overall equipment status at a glance.

Of course, the light suppliers prefer to sell more elaborate models, but I have never met an operator who could tell me what White with blinking Blue was supposed to mean, especially when it was not consistent across machines. So, if you see that, you know that the lights are just there for decoration.

Visual versus verbal communication

Reliance on words is not recommended for an audience that does not have a common language. That is why traffic signs in Europe are mostly wordless and European car dashboards are covered with pictograms, that are sometimes but not always self-explanatory, which is why I have taken to calling them “euroglyphs.”

An American car dashboard with words is actually easier to understand, but only if you know English. Like European roads, a California production shop floor may have a work force with multiple nationalities and uneven English proficiency. As a consequence, using words for instructions or safety warnings is not much of an option.

Two resources I find helpful is thinking through these issues are usability engineering experts Don Norman, author of The Design of Everyday Things, and Asaf Degani, author of Taming Hal.

If you include hearing, touch and smell, I suppose it should be called “sensory management” rather than “visual management.” If we use “visual management” for all forms of sensory management, what term are we going to use for what is specifically visual?

Visual management as part of the information system

The term “information system” should encompass all the means used in a plant to exchange and process information. Visible management is part of it, along all the computer applications, from CNCs, PLCs and SCADA systems to corporate servers for technical and business data. They are all components of the same information system and both are needed to run a plant.

Japanese terms for visible management

The Japanese term I have heard for visual management is ”medemirukanri”(目で見る管理), literally “management you can see with your eyes.” Mieruka (見える化) is new to me; it means “transformation into something visible.” I see it as an improvement, as it is shorter and just as self-explanatory. I suppose you could say that medemirukanri is the result you achieve and mieruka the process by which you achieve it, but I don’t see that nuance in the usage.

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Jun 21 2013

Using videos to improve operations | Part 6 – Quick simograms

Here, we finally start collecting measurements from the video, focusing on what we can collect while watching without stopping. In this mode, we can break down operator time by broad categories like  “Waiting,” “Walking,” or “Assembling,” but we don’t have the time to name each task and collect comments or improvement ideas. This will require a more detailed and time-consuming analysis. 

One method, developed by Christophe Caberlon, involves two analysts, one viewing the video and the other one filling out an electronic spreadsheet. Instead of looking for state-change events in the video, we look at it in 5-second increments. Every five seconds, the analyst viewing the video calls out the state the operator has been in since the previous call. Each 5-second. Interval is assigned one column in the spreadsheet and there is one row for each state. Based on the call, the second analyst switches the color of the cell for the state and time interval.

Counting in 5-second intervals involves aliasing, but it is not a problem for a rough-cut estimate. The rows in the spreadsheet do show the state transitions in a Gantt-chart like format called “simogram,” and can summarized into proportions of time spent in each state, as in the following example:

Simogram example

This example uses cell background color to express content, which is not generally recommended because Excel does not provide built-in tools either for quick input or for analysis. The result, however, is graphically much more attractive than filling the cells with Xs. Changing the background color of a cell requires multiple steps, which cannot be repeated every five seconds. These steps, however can be recorded as a Macro. In this example, the macro has Ctrl+q as a hot key to mark a cell and Ctrl+w to unmark it. Also, each 5-second time segment must be assigned to one and only one category. When working your way through a video, it is impossible to avoid cases where one segment will be missed and another accidentally assigned to more than one category.

To detect these errors, we need to count the gray cells by column, and to summarize the times into relevant aggregates, we need to count them by rows. While Excel provides no built-in function to do this, you can find add-on modules to do it. The modules used above are due to C. Pearson. 

This method is also restricted in the number of states to track. It is feasible for two or three but not fifteen. With the limited number of choices, it is a good idea to include an “Other” state. The states should also be clear and unambiguous, such as:

  • Walking: the operator’s legs are moving.
  • Working: the operator’s hands are moving.
  • Waiting: all the operator’s limbs are still.
  • Touching: One of the operator’s hands is touching the product.

Categories that are abstract and subject to interpretation, like “Value-added” should be avoided. Note also that an operator who is Working or Touching, may be handling the work piece or transforming it, and we don’t have enough categories at this level to make the difference. 

Timer Pro provides a method called “Non-stop timing,” in which the analyst simply clicks on a category when observing a state transition, and the time since the previous click is automatically assigned to this category. This eliminates the aliasing due to using 5-second intervals, and relieves one analyst from the task of clicking the right spreadsheet cell every 5 seconds.

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Jun 8 2013

Using videos to improve operations | Part 5 – Watch it in fast motion

Christophe Caberlon has a special way of conducting this first step: at 6X normal speed. When reviewing videos with the operators who have been recorded, he has found that accelerated motion has the effect of drawing attention to the activities that consume the most time, as the ones that do not are filtered out. If the operator spends the majority of the time walking back and forth to a shelf to pick parts, a fast-motion viewing of the recording makes it dramatically obvious and compelling, making the operator eager to help improve the process. After trying various 2X, 4X and 8X, he has found that the 6X ratio of acceleration works best for this purpose.

When Christophe  told me about this, it reminded me of a scene in the movie The Hunt for Red October, in which sound is used the same way. Jonesy, the sonar operator in the American submarine tracking the soviet submaring Red October, has just heard the sound of the propellers disappearing when the Russian boat turned on its “silent” propulsion system. But he still heard a vague rumbling. The analysis software categorizes this sound as magma displacement, but the sonar operator believes that the sound is made by the submarine. To convince his captain of that, he plays the recording at 10 times the speed, which turns the rumbling into a rythmic “tac tac tac” characteristic of a human artifact and not magma displacement.

The idea of watching the video in fast  motion is that, by filtering, it lets you see patterns you would otherwise miss. The same is true of slow motion, but fast motion has the advantage,… of being fast. You wouldn’t want to review an entire 1-hour video in slow motion, but you may do it in a few excerpts as part of the detailed analysis we will go into in a coming post.

Of course, the idea of reviewing a video in fast motion is more interesting if you can actually do it, and the most common video players around don’t let you run at 6X. I tried the following:

  • Quicktime V. 7.7 through “A/V controls” lets you run videos at speeds up to 3X.
  • Windows Media Player does not let you change the speed.
  • Real Player lets you change speed by powers of two by pressing Ctrl-Shift-F4, but the resulting accelerated videos are not watchable.
  • VLC media player lets you use any speed up to 4X, and powers of two beyond, up to 32X.

Among video editors, Windows Live Movie Maker lets you change speeds, but Google’s Picasa 3 doesn’t. For Windows Live Movie Maker, it is again in powers of 2.

In video annotation software, ANVIL doesn’t do fast-motion, but Timer Pro does. To view a video in 6X in Timer Pro, you click on the Video tab and set the speed to 12. The video then plays at the right speed but the a wrong aspect ratio. If, however, you click on the Comparison tab, you can view at 6X normal speed and with the correct aspect ratio, albeit in a small window that you cannot adjust.

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May 31 2013

Using videos to improve operations | Part 3 – Shooting shop floor videos

Following are a few recommendations on the art of taking shop floor videos:

  1. Special requirements on shop floor videos. We have already seen that the requirements for shop floor videos differ from those of other uses of this technology. If you shoot a family or sports event, you will naturally want the highest resolution you can get, which would be counterproductive here. Likewise, shooting a video for the purpose of data collection is different from doing it for art or entertainment.For example, the Youtube video of a NASCAR pit stop looks somewhat like a shop floor video but isn’t one. It is entertaining and dramatically shot, but not usable for analysis. In fact, a shop floor video that captures everything that is needed for analysis is likely to bore anyone who is not directly involved with the target process.

    This needs to be considered when deciding who will be holding the camera. You will naturally prefer someone who is already handy with it, and that is likely to be from experience capturing family occasions, sports, or from making movies as an amateur. The ability to keep a camera steady and pay attention to lighting, composition and focus is valuable, but the camera operator will have to be coached on the specific objectives of shop floor videos.

  2. Applications to setup time reduction or to the improvement of a work station. the camera needs to be looking down at the operator’s hands. In short operations, it can be done by holding the camera with a raised arm, and using the swiveling LCD screen for control. This gets tiring quickly and requires standing in such close proximity to the operator as to possibly interfere with his or her movements.
    Many plants have mezzanines or catwalks that provide a view from above. Being observed from such a place, however, may be uncomfortable for the operators, as well as too far to zoom in on the hands and capture any voice comments. The middle ground is to shoot from the top of a stepladder located within zooming and hearing range of the operator station, just far enough to avoid any kind of interference

    Amin recording operation
    Shooting a video from a stepladder.

    This works, until the operator leaves the station to walk beyond the reach of the zoom, at which point getting down off the stepladder to follow the operator while recording causes a few seconds of the action to be lots. A better solution is to hand over the camera to another team member on the ground, or even to involve more than one camera. In any case, this needs to be planned. Image stability is not an issue on the stepladder, but it is when following an operator’s movement across the floor, and you do not want a video that will make participants sea-sick during review. While professional tracking shots require equipment that is not available in a factory, some amateurs have supplemented the camera’s own image stabilization by shooting from a wheelchair.

  3. Fixed position on a tripod for time-lapse videos. Setting the camera on a tripod in a fixed position is not appropriate for this kind of analysis, but is when taking time-lapse videos of a large area for purposes of work sampling.
  4. Recording the position and orientation of the camera. It is also necessary to record on a layout of the shop floor the position and orientation from which the video is shot. The point is to return to the same location to shoot another video to document the improvements once implemented.
  5. Number of repetitions. Traditional time studies involve taking measurements on the same operation 6 to 10 times, for the purpose of improving precision when setting standards of operator performance. But our purpose in recording operations is not to set standards but to change processes to make the work simultaneously easier, safer, less error-prone, and faster.
    All we need for this purpose is one representative execution, and the operator can tell us if there is anything special or abnormal about it. If possible, we just take it into account during the analysis; otherwise, we make another recording. To make sure we have one complete execution, we start recording a few seconds before the operation starts and stop a few seconds after it ends.
  6. Scale. The presence of people in the videos gives us at least a rough sense of scale, but sometimes we would like more precision, for example to know how far an operator has to reach for a part, or how fast a cart is rolling. The following shots show the extreme measures the Gilbreths took for this purpose, with a gridded background. The picture also shows a large and precise timer, which was necessary because they used imprecise hand-cranked cameras.
  7. No editing. We do not edit the shop floor video, except possibly to add a title and administrative data at the beginning, Otherwise, we use it in the analysis exactly as shot. It is raw data, and we want to keep it that way.

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May 29 2013

Using videos to improve operations | Part 2 – Management Preparation

Whether on the shop floor or elsewhere, starring in a video makes people nervous, particularly when they don’t know how it will be used and when it is done by strangers. On the shop floor, particularly when unions are present, operators fear that the videos recordings will simply be used against them and to  justify layoffs. Unless these fears are put to rest before the shoot, it will be tense and, if it happens at all, the quality of the data will be affected.

Following are key steps to follow:

    1. Have a clear objective. Videos can be used for many purposes:
      • Setup time reduction. This is the most common current use in Lean implementation.
      • Work Sampling. A time-lapse video of a work area can be used as a series of snapshots on which to count the people and machines by category of activity, providing rough estimates of proportions of time spent walking, waiting, carrying parts, processing work pieces, etc.
      • Analysis of team coordination. You record from a distance the movements and state changes of multiple people and machines. You don’t see the details of what each one does, but you identify situations where they:
        • Walk long distances, empty-handed or carrying heavy parts,
        • Cause others to wait,
        • Deadlock each other,
        • Fix the work done by others,
        • …
      • Details of work done at an individual station. You focus on the hands of one operator through a sequence of steps at a work station, with the goal improving both individual steps and their sequencing.
      • …

      This is necessary not only to plan the shoot so that the video supports the objective, but also to identify the people who will be recorded and the ways in which the analysis may affect them.

    2. Secure the consent of the participants. The people recorded in the video are not the object of a project but participants in it. It should only be done if they and their management agree. This entails the following:
      • Review the project with the direct supervisor of the area first, and proceed only if he or she supports it. The supervisor needs to agree to let operators participate in video analysis sessions, during work hours if they can be temporarily replaced in production, and in overtime otherwise.
      • If the plant is unionized, review the project with the union leadership. Unless prevented from doing so be constraints external to the plant, unions support the project once they are reassured that:
        • The purpose is not to make people work harder.
        • It is no threat to job security.
        • It usually improves safety.
      • Review the project with the operators, in the presence of their supervisor and a union representative if applicable.
      • There must be a clear policy on the handling and dissemination of videos after the analysis. The principle to follow is that what happens on the shop floor stays on the shop floor. The videos are not to be shared with any outsider to the project. VHS cassettes were easy to safeguard; MPEG files on hard disks are a different challenge. They need to be organized in a video database with proper indexing and safeguards, which is a whole other subject.

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