Technology

Oct 19 2013

A New Approach to Materials Handling in Warehouses

In a discussion in the TPS + 1 SENSEI group on LinkedIn, Casey Ng drew my attention to a materials handling approach from Kiva Systems, a company started up in Boston in 2003 by engineer/MBA Mick Mountz with funding from Bain Capital, that is now a wholly-owned subsidiary of Amazon. The following is a promotional video from Youtube:

The system shown in the video is clever, and can certainly be useful in fulfilling Amazon orders or in kit picking for assembly, but it is also obviously not a panacea. It only supports a single-level of racks, and boxes or bins that can be lifted by people. If you wanted to use the overhead space for storage, you might combine it with a classical automatic storage and retrieval system, which would move the portable racks to and from from upper levels for further handling on the ground by the Kiva pods.

Bringing materials to an operator at a fixed location rather than have the operator travel to do the picking is what is also attempted by carousels, but carousels require the operator to wait up to a half-turn for the right slot to be presented, and are limited in the number of items they can carry.

Cheesecake-factory-device-in-Kiva-warehouse with highlightAs shown in the video, while the concept is innovative in terms of storage and retrieval, it does not stretch hardware technology.  As we see on the video, we see the operator who loads boxes onto racks for putaway use devices that look like the ones used in restaurants like The Cheesecake Factory or the Fish Market to notify waiting customers that their tables are ready. The pods look like giant Roombas, but move in a more restricted manner. According to Mick Mountz, the pods just move around the grid of small squares marked on the floor with optical guidance and a simple form of “after-you” system to avoid collisions. On the video, auto-ID seems to be based on plain old barcodes. There is no mention of RFID or even QR-codes. The actual transfer of boxes is manual, with a form of pick-to-light guidance. While less visible, the software that coordinates all the moving parts is clearly at the core of this system.

I learned of Kiva’s existence this morning, and have no relationship with this company.

 

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Oct 15 2013

Perfection Through Mistake-Proofing | IndustryWeek

See on Scoop.it – lean manufacturing

“Mistake proofing can make a significant difference in the output of any process [….]  Mistake-proofing devices should meet three criteria:

          1. Simple
          2. Infallible
          3. Effortless”
Michel Baudin‘s insight:

The article makes the point that mistake-proofing must be “effortless.” The way I usually say it is that a mistake-proofing/poka-yoke device must not add labor, a point that is frequently missed in discussions of this topic in the US.

Why is it essential? Because any device that adds labor is guaranteed to be by-passed under pressure. If preventing a mistake requires one more gesture, on any day where “we have to ship all this by 6:00PM,” the organization will find a way around it.

Mistake-proofing makes a difference in any process where human error is a major cause of failure. Many processes qualify, but not all. If the main cause of defects is the machine’s  inability to hold tolerances consistently, mistake-proofing will not do much good.

Yes, a device that is fallible cannot be considered mistake-proofing. Usability engineering, for example, provides user interfaces  that make mistakes unlikely, but not impossible. Sometimes it is sufficient, but it is not mistake-proofing.

The one criterion I have an issue with is simplicity. A mistake-proofing device must be simple to use, I agree, and its design should not be anymore complex than necessary. However, where the stakes in human error are high, as in airliner cockpits or semiconductor process equipment, preventing mistakes may require elaborate technology. If a device for this purpose  works every time and adds no labor, I see no reason to deny it the “mistake-proofing” label.

See on www.industryweek.com

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Karakuri doll serving tea

Sep 17 2013

What is Karakuri Kaizen?

Google “Karakuri Kaizen,” and you see a small number of Youtube videos from Japan, Thailand, Italy, and Hong Kong showcasing materials handling devices that rely on gravity, levers, cams and inertia to move bins in elaborate ways, transfer parts between machines, or deliver a controlled number of small parts to an operator’s hand.

Here is one from Japan’s JMAC with multiple examples:

Such devices have long been used as part of TPS and Lean, but now we have a generic name for them. The principles of Karakuri Kaizen given at the end of this video are as follows:

  1. Don’t use the human hand. Move objects automatically.
  2. Don’t spend money.
  3. Use the force of your equipment.
  4. Build it with the wisdom and creativity of the people of the shop floor.
  5. For safety,  don’t just rely on paying attention but build a device that stops automatically.

While “Karakuri Kaizen” is an alliteration that rolls of the tongue almost as easily as “cash for clunkers” or “toys for tots,” you may still wonder where “Karakuri” comes from and what it means. Until “Karakuri Kaizen,” I had never heard it stand-alone but always as part of “Karakuri Ningyo,” or Karakuri Dolls, which are wind-up automata with wooden gears and levers developed at toys in 18th-century Japan. The best known are tea-serving dolls, like the one in the featured image.

As Karakuri dolls are a reminder of ancient ingenuity, the term has a positive connotation in Japan. I once used a picture of one in a magazine ad for US-made automation software, to connect the product with the local culture. But the term, obviously, means nothing to anybody who is not Japanese.

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Jul 23 2013

Standard Work in Low-Volume/High-Mix Manufacturing

In the TPS Principles and Practices discussion group on LinkedIn, Brian Miller initiated a discussion on “How do you create standard work for a customized product that has over a billion combinations?” It has had 31 comments so far, and I would like to share here a few that I made.

Even in a plant that is perceived to be focused on low-volume/high-mix production, you usually have an uneven demand pattern, calling for different approaches to standard work by product category.

You start with a Runner/Repeater/Stranger analysis to determine what it is we do often and what not. Without this analysis, we commingle in the same lines products made every day with other products made sporadically (See Lean Assembly). In Japan, this is called P-Q, or Product-Quantity analysis, with the categories called A, B and C. The more vivid Runner/Repeater/Stranger terminology comes from Lucas Industries in the UK. You then use a dedicated, integrated production line for each Runners, a flexible line for each family of Repeaters, and a job-shop with functional groupings of equipment for Strangers.

Then, obviously, you face different challenges for developing standard work in each category:

  1. In a runner line, you can post A3 sheets above each workstations with instructions for the purpose of allowing supervisors to monitor how the work is being done. This is the normal situation of high-volume production.The operators themselves do not need to read the instructions for every workpiece; as soon as they are proficient in the job, they work from memory.Operator instructions in auto parts assembly
  2. A repeater line is for a family of products with variants but with a high commonality of materials and processes. The instructions that can be posted on A3 sheets are then limited to the common processes, but the operator needs to read what is specific to each workpiece. For final assembly of cars, Toyota has provided “build manifests” printed on larger sheets mounted on car bodies and bearing all the option information. The kitting of workpiece-specific components also helps. In computer assembly, workpiece specifics are shown on electronic displays, with component picks validated by auto-ID technology, including bar codes, QR-codes, or RFID chips.Toyota build manifest Valenciennes cropped

    Kit-trays-with-instructions-web
    Kit trays with instructions for repeaters in electronics assembly
  3. Strangers are the odds and ends with sporadic demand, one-of-a-kind systems, or new product prototypes. For strangers, you cannot rely on operator memory or habit. For one-of-a-kind systems or prototypes, you cannot even assume you have the knowledge needed to produce workable detailed instructions. Each stranger is a job in a job shop and requires instructions on a traveller that moves with the workpiece. The traveller may be hardcopy or electronic. An electronic traveller may either be a device containing all the instructions or an ID that triggers the download of appropriate instructions at each station. Strangers are usually built by skilled craftsmen able to work directly from engineering drawings. Given the nature of strangers, however, the time required cannot be precisely known and sequencing mistakes will happen, making rework inevitable.
Stranger assembly in Yatai at Omron
Stranger assembly in Yatai at Omron

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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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