Katacon Europe 2018

Many months ago I was approached by the European Katacon organizers to help setting up the 2018 conference. Katacon is about kata, the Toyota Kata revealed to the mass by Mike Rother in the book… Toyota Kata. It’s about patterns of thinking and behaviour to improve and solve problems.

I modestly offered my website, blogs and networks as sounding boards to the event, not able to do much more. Now time has come to advertise the coming event!

Katacon Europe 2018, where and when?

Amsterdam will be the location, more specifically B. Amsterdam, a creative work space bridging startups, creatives, and corporates. (http://b-buildingbusiness.com/amsterdam/)  located Johan Huizingalaan 763a, 1066 VH Amsterdam.

The date is April 18 & 19, 2018 with a preconference afternoon and a Kata geek meeting for early comers to network.

The program is detailed here: http://www.katacon2018.eu/day1.php

What’s offered to participants?

If you go through the program, you’ll see that DAY ONE, besides welcoming and opening speech has 4 mini keynotes on Improvement Kata, before participants spread into study visits or workshops of their choice. Everybody meets again for the networking diner at 19:00 (7 pm).

DAY TWO starts with plenary sessions: reflection from day one, Finding new ways to learn and a testimony about Toyota senseis’ mentoring and comparing Kata with a professional sports coach. By 11:00 it will be time to breakout into various sessions to select (chose twice 1 in 5)  and plenary sessions will resume from 15:30-17:00.

Registration: http://www.katacon2018.eu/registration.php

I hope you’ll find a lot of value and have fun!

About the author, Chris HOHMANN

About the author, Chris HOHMANN

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Goal Tree Chronicles – Coloring the Goal Tree

The 3-colors system is a well accepted assessment and visual management tool by Goal Tree builders and users. The principle is simple as it uses the traditional Red-Amber-Green color code to indicate the status of each entity in the Tree.

In a Goal Tree, Necessary Conditions are enablers to the above entity. As soon as enablers are not in place or “unstable”, the outcome they should enable cannot be considered as in place, delivering or achieved.

In this post, I detail how to color a Goal Tree.

How to color a Goal Tree?

Start at the bottom, with the very basic Necessary Conditions. Have the Subject Matter Experts (SMEs) assess each Necessary Condition for its status. As soon as a basic Necessary Condition, which is a requirement or prerequisite to the above entity to exist, is Amber or Red, the above entity can only be Amber or Red. The color, symbol for the status, propagates upwards like in a line of dominos when the falling one pushes the next.

Goal Tree

Reminder: in “my” 3 color system, green stands for granted, constantly available, steady… Amber means unstable, not totally fulfilled, variable… Red means missing, non-existent, not at nominal value, etc.

Therefore, the assessment can be quite quick. The SMEs should know what’s going on on shopfloor, how process behave and deliver. Key Performance Indicators (KPI) may give additional information.

In a starting project, chances are that many identified basic requirements are not yet fulfilled, so their boxes in the Goal Tree are red. As soon as such an entity turns Amber or Red, no need to assess the above related entities, they are Amber or Red by definition.

Related: Goal Tree: How green is your tree?

The requirements that are Green need to be followed upwards nevertheless to see if their above related entities are Green as well, or if an additional Necessary Condition coming in sideways has a non-Green status. If this is the case, the above entity takes the color of the worst of the underlying Necessary Conditions’ color.

The limits of the 3-color system

It can happen that despite an entity having all its underlying Necessary Conditions set to Green can’t be assessed as Green. Facts and figures just don’t allow it. How come?

Well, remember: underlying Necessary Conditions are enablers, not triggers. Unlikely what happens with sufficiency logic where a cause is literally sufficient to produce the effect, the necessity logic used in the Goal Tree states that if a Necessary Condition is missing, the expected effect can not happen, but conversely, the underlying Necessary Condition existence is only enabling the effect to happen.

Entities in a Goal Tree are also called Intermediate Objectives and in order to achieve an objective, 3 conditions are required: having the necessary means to achieve the objective, knowing how to achieve it and being motivated to achieve it.

Related: What it takes to achieve your objective: Means, Method and Motivation

In case a should-be green Intermediate Objectives isn’t green, you should check the Means, Method and Motivation.

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About the author, Chris HOHMANN

About the author, Chris HOHMANN

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About Clarity, Focus, Discipline, and Engagement

This post is inspired by Karen Martin’s (author of Shingo Research Award-winning book, The Outstanding Organization)  interview by Ron Pereira (Gemba Academy). In this interview (https://www.ksmartin.com/videos/the-outstanding-organization-interview/) Karen explains the importance of Clarity, Focus, Discipline, and Engagement. These are the four fundamental behaviors or common patterns in successful organizations, that are strong foundations upon which to build improvement programs up to outstanding organizations.

This interview resonated with me especially because the company I was trying to help at the very moment I heard the interview lacked every one of these four “pillars” and I truly believe this was the cause of all its trouble.

Here is my take on Clarity, Focus, Discipline, and Engagement, piggybacking on the interview. These opinions are mine, they may not reflect Mrs Martin’s opinions.


Clarity is first of all about the clarity of purpose, about making it very clear for everybody within the organisation what the organization is supposed to achieve. Why the organization was put in place in the first place and/or what Goal the founders are/were pursuing?

This Goal can be referred to as “True North” in Lean parlance and is called the “Goal” in the Logical Thinking Process. Both are a long-term objective that will turn a Vision into reality.

Once this purpose is clearly communicated, everyone can align his/her actions onto the organization’s Goal. Management is supposed to derive contributing intermediate objectives that make sense to their subordinates, in their daily jobs, while ensuring alignment onto the Goal.

Yet when circumstances require swift decisions, even without management around to give instructions, the clarity of purpose helps subordinates to take consistent decisions with the organization’s Goal.

Clarity is also, according to Karen Martin, about the lingo in the organization. Indeed, many employees use acronyms they are often unable to explain or worse, don’t understand! This makes it tough for any newcomer or temporary help to be at ease with the job, procedures, etc.

It can lead to misunderstandings, errors, interpretation, ambiguity, and slowing a process that could run smoothly if everything was clear.

For knowledge workers or for those that can work from home, without as much guidance and reminders than in a corporate building, clarity about the Goal is also important in order to keep focused.


With clarity of purpose it is easy* to focus on what really matters. Resources and time can be well used on what is important. Conversely, lacking clarity opens many options to go astray and waste precious and scarce resources on the wrong things. Alas, the latter is more common than the former.

When some people lose their focus, it is easier for themselves, for management or even colleagues to remind the Goal and what to focus on and why, when the Goal has been stated with clarity, communicated, and repeated.

Focus requires also to track progress with KPIs and review the progress regularly in order to correct the deviations.

*Staying focused needs discipline.


Discipline is about the ability to stay focused on the objective or to accept being reset onto the right objective. Discipline is also about sticking to the rules, using the defined standards, the official good practices, methods, systems and tools. Without sufficient discipline, chaos finds its way in. Little variations, little bits of ill-used freedom may lead to major problems.

It doesn’t look very harmful to download data from an ERP into a spreadsheet and drive processes from this copy, but at some point data may be so divergent that the situation becomes a mess. A little deviation messed up in unexpected proportions.

How many times manual data inputs do not follow the rules and the dataset is littered with entries that should be in the same format but do not accumulate properly because of scripting variations?

Now some degree of freedom is necessary to adjust to the circumstances as no procedure or work guide can describe every possible case and provide all necessary answers. So discipline is also acting in the interest of the organization while remaining the closest to the rules and standards. The latter should be adjusted with the lessons learned.

I was shocked to hear that some people in an organization, without the position giving them the freedom to act like this, chose themselves to stop reporting or stop attending meetings. I was even more shocked to hear that management did not react to these deviant behaviors. Here the lack of discipline goes both ways, bottom-up and top-down.


Engagement is the commitment to work on achieving the organization’s Goal. It is, in my opinion the result of Clarity, Focus and Discipline that provide the necessary framework, with sufficient empowerment to adjust to circumstances plus the feedback and management support to keep motivated.

Many surveys show that disengagement is way more common than engagement. So if we start from disengagement all the way back up, we can assume that disengaged staff doesn’t take it so seriously with discipline, as they don’t care.

If there is no motivation and probably poor discipline, focus is not likely to be kept on what matters. And if focus isn’t kept nor reinforced, it doesn’t matter if the purpose and the Goal have been communicated with clarity.

Employee engagement is key and engagement is something the organization can only facilitate but not order nor buy.

About the author, Chris HOHMANN

About the author, Chris HOHMANN

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Don’t do unto others what you don’t want others to do unto you

If you check the Internet for this quote, chances are that it will be attributed to Confucius. It’s variations can found in many religions and cultures (https://en.wikipedia.org/wiki/Golden_Rule) and can be easily understood as a basic code of conduct in a relationship based on reciprocal respect.

Now here is an incoming (unsolicited) e-mail from an unknown lady. She’s offering me to give a course in some public sector in-house university. For me the interest is limited, but the mail is very polite.

The proposal does not fit my agenda nor the usage I’d like to do with my very scarce private time, but in order to be polite and acknowledge the opportunity, I will of course answer.

The irony is that immediately after my answer was sent, an automatic mail message came back, explaining that my correspondent wants to shield herself off any unwanted e-mail (spam of course) and therefore, if I wish to overcome the digital blockade, I have to go through a procedure to identify myself.

If I don’t, the time invested in my polite reply will be lost as well as my nice guy reputation.

Hmm, isn’t it ironic that this lady, protecting herself from unsolicited e-mails:

  • doesn’t apply the same rule to herself
  • amplifies (involuntarily I believe) the inconvenience for the people she’s more or less asking a favor from.

So I went through the procedure and invested more time. I then felt this could be shared as a post on my blog and invested much more time.

Thank you lady. If you happen to read this post, please meditate on this maxim: Don’t do unto others what you don’t want others to do unto you. And check your anti spam policy.

About the author, Chris HOHMANN

About the author, Chris HOHMANN

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Quick look back to 2017

The first days of every new are usually the time to reflect about the past twelve months and make plans for the next twelve to come. As I write this post, 2018 is already 13 days old but probably not too late to look back to 2017 blog-wise.

This blog went online in January 2014. Tada! 4th anniversary!

In these 4 years, the blog accumulated 401 post, was visited by 110,132 visitors / 197,589 views. 142 visitors found worth enough to click the follow button. Thanks to them all.

This is all organic.

Twitter and LinkedIn are my best sounding boards, with reblogging from or embedding in other blogs.

In 2017, I found time to write and publish 53 posts. Roughly one per week.

Besides this blog I try to feed my French website, my latest French Blog and my YouTube channel. All this mostly during the weekends when the family members still sleep or don’t care about me… Some of my posts were written during traveling, or while walking and dictating to my smart phone.

What blogging plans for 2018? Try to post regularly, try to share value, have fun.

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Are the 5S the first steps to SMED?

This is a classical debate among Lean newbees and even among specialists: are the 5S the first steps to SMED or not? As so often there is more than just a binary choice.

Yes, 5S are the first steps to SMED

Let’s start with the pros. The 5S are a good way to restore basic conditions enabling efficient and safe work in a “legible” environment, where the clutter is taken away and everything is made simpler and visual.

5S do not only get rid of the clutter but require to fix broken equipment, replace worn out tools, overhaul machinery… 5S define rules for sharing common hand tools, locate items, make the current condition immediately visible and from far away.

The very example of this is the shadow board outlining the tool’s shapes. When a tool is missing or hung on the bad location, it can be spotted from a distance, saving the walking to the board to discover the needed tool is not available or out-of-order.

This works with document files, with the famous slant line across the file’s back. Any missing or ill-positioned file breaks the line.

5S will save a lot of time searching for tools, fixtures, documents and avoid mismatching the different versions. 5S rules are defined by the area workers themselves. They are regarded as Subject Matter Experts and the decision of how work environment should look like is delegated to them. With some limits though; 5S rules can never trump safety and health regulation rules, for example.

5S are especially recommended when trying to reduce the changeover duration with SMED.

When trying to reduce all wasted time when changing from one production batch to the next or from one production series to the next, searching for tools, jigs, fixtures, documents, parts, material, etc. is no option.

Prior good 5S help a lot smoothing the changeover operations and significantly reduce the waste of time.

5S are easy in appearance, but hard to sustain. Therefore I respectfully consider them as a school of rigor and discipline. If an organization is not capable to bring its operations and supporting departments to a high level of 5S maturity and sustain it, chances are that introducing more demanding and more complex tools and methods will fail.

That’s why I agree, 5S are the first steps to SMED.

No, 5S are NOT ALWAYS the first steps to SMED

When an organization is in the “burning platform” state, meaning quick action is required to fix a major problem, restore customer service, or bring back a decent performance level, starting with a 5S program deployment is probably not the best option. This would look like arranging the chairs on the sinking Titanic, or in plain language: diverting precious time and resources focusing on the wrong objectives.

It might surprise newcomers to SMED, but two specialists having opposite opinions about starting a SMED program with or without 5S might be both right. The good choice is simply condition-related.

If more productive capacity is direly and urgently needed, 5S is not the best option to start with. “You don’t ask people to tidy up their workspace!” as one once angrily argued. And he’s right, but he didn’t consider other conditions than the ones he was familiar to.

If the main objective is to let operators learn about the Lean basics and hone their waste-spotting capabilities, 5S would be a good pick for a starter. It brings people to gradually understand the importance of rigor and discipline as well as to continuously improve the work environment and work execution itself.

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What it takes to achieve your objective: Means, Method and Motivation

When facing a challenge, many subordinates quickly complain about the lack of means and  scarce resources. But what it takes to achieve an objective is more than just means.

The common complaints about means

Complaining about scarcity of means or resources is a convenient way to push the responsibility of the difficulty of the challenge and the possible failure to the boss, and often comes without any evidence for the resources really being scarce.

You may like my post Do what you can, with what you’ve got, where you are

Time allocated to achieve something can be considered as a means. If the management gives no time or too few time for some tasks but expect a result nevertheless, the complaint about not having enough time can be legit.

This is the case with daily machines cleaning  (Autonomous Maintenance) after the shift is over, allocating some time to stop production and clean, lubricate and visually inspect the machines for the sake of failure prevention. But if production is late and management orders to work till the very last minute, there is no time left for the daily basic maintenance. If this is repeating over and over, the machines’ condition may decline and a serious failure stop them for a longer period.

Some means are absolute prerequisites to achieve the objective and if they are not granted, the objective may be out of reach, despite the alternative or creative ways people try.

Means are also often confused with method or a process, and people complaining about insufficient means are in reality worrying about how to proceed. Having the appropriate means is then synonymous to knowing how to do, with the hope that this or that tool, machine, equipment, etc. will bring the solution with it.

The triple prerequisite to achieve an objective

Besides appropriate means, the method or way to proceed is another prerequisite. If you get all the parts necessary to assemble a computer but have no idea how to assemble them, you have all the necessary means but are still unable to have a working computer. Therefore, the second prerequisite, besides means, is method or know-how or knowledge, procedure, instructions, etc.

There is a third prerequisite to achieve an objective: motivation. If you have all necessary means and have necessary know-how and skills but no motivation (or will, desire), the objective will not be achieved.

The triple requirement for achieving an objective is to have appropriate Means, Method and Motivation, which can be memorized as 3Ms.

Now when assigning tasks or objectives to teams, managers better make sure the means are provided, the know-how or skills are available and check the motivation.

This post was inspired by an explanation of my friend and mentor Bill Dettmer during a Logical Thinking Process training course. You may listen and watch Bill’s explanation in the video beneath. To understand the context you may read my post Goal Tree Chronicles – Enablers vs.triggers.

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How to identify the constraint of a system? Part 5

This is part 5 of a series of posts about identifying the constraint of a system and time for wrapping up and a conclusion (of the series, not the topic!).

Newcomers to Theory of Constraints understand quite easily the concept of bottleneck but are frequently puzzled when looking for them in a real-life process. Furthermore, people have usually difficulties to distinguish bottlenecks or Capacity Constraint Resources from the system’s constraint. As only the latter controls the Throughput of the whole system, meaning it does control the system’s profitability, constraint hunters should better not mismatch the focusing point.

Through the examples in the previous posts, readers can understand that there is no such a thing like a simple trick, neither ready procedure to find the constraint, but a necessary and sometimes painstaking investigation process.

If you missed previous posts, you may check:

Some constraints can really be well hidden and remain elusive, leading analysts to be wrong when identifying it. Because of the growing number of standard and regulatory requirements, the constraint is more and more often found in the paperwork process, in quality assurance or information flow. And this is the wrong place for the constraint to be.

How to be sure the constraint is found?

With so many opportunities to mismatch the constraint, how can one be sure about having found the constraint? Well, by definition the constraint controls Throughput. Elevating the constraint is like opening a valve, the flow through the constraint increases. And as, also by definition, all other resources have excess capacity compared to the constraint, the flow should soon reach the process’ output. This enables the organization to ship more, to ship on time, take more orders and shorten time-to-cash.

For non-profit organizations, the Throughput is expressed in “Goal units”, meaning achieve more of what the organization exists for, like treating more patients for a medical center, providing more food to the homeless, etc.

Now this is quickly noticeable if the downstream process steps are waiting for supplies from the constraint, otherwise the flow from the constraint may take longer to reach the process’ end.

Be aware of the S curve and Valley of despair

As with many improvement initiative, the result may be delayed to a point that some stakeholders come to the conclusion it doesn’t work. Before getting trapped in this pitfall, the project manager or the leader should be aware of the frustration with the S curve.
When dealing with bigger projects rather than improvement activities, it’s not only the S curve the project manager and the sponsors should worry about, but also the “Valley of despair”. This valley is a low in morale following the excitement and expectations about the benefits that the new project will bring. The drop in morale comes when issues and bugs let the new solution appear worse than the old. The challenge for the leader is to get everyone as quick as possible through the valley of despair, accommodate the new way or system and eventually recognize the benefits.

Keep on alert once the constraint is found!

Now once the constraint is properly identified and the efforts to exploit and elevate it begin, the leaders should immediately take care of the consequences of releasing more “goal units” through the constraint.

  • First because the constraint will most probably move to another spot and again this can be anywhere in the process.
  • Second because upstream as well as downstream process steps may be taken by surprise. Upstreams by an increase of demand in order to supply and exploit the increased capacity. Downstream by the flushing of the work in progress that may propagate a significant wave of workload.
  • Third because management must anticipate any necessary action to sustain the flow at the new level, otherwise the success will only be sporadic and ultimately disappointing.

I recommend reading two other posts related to these warnings:


The search for the system’s constraint can be very simple and straightforward, but most often it is tricky and leads to identify wrongly some resources as culprits. It is no rocket science but needs investigation skills and rigor. Experience helps a lot and the good news is that taking care of constraints is never-ending, so experience may accumulate fast.

About the author, Chris HOHMANN

About the author, Chris HOHMANN

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How to identify the constraint of a system? Part 4

Since the publishing of early books on Theory of Constraints, the world grew more complex and the system’s constraint got more and more elusive. Globalization and extended supply chains give a constraint opportunity to settle literally anywhere in the world and extend its nature. It can be a physical transformation process in a supplier’s facility, it can be the way cargo is shipped from distant suppliers to the company, it can be the custom clearance process somewhere along the supply chain.

Walking a factory door to door may not suffice anymore to find the system’s constraint. The examples given in the part 1, 2 and 3 of this series of posts are simplified with regard to the reality of most companies.

Another complexity is brought by the growing number of requirements of standards and regulations. A company wanting to count among the aeronautical industry makers has to comply to the AS 9100 (USA) / EN 9100 (Europe) / JISQ 9100 (Asia) standard. For the automotive industry the standard to comply to is ISO/TS 16949 (now IATF 16949). And those two examples are only standards for the quality management system.

Pharmaceutical industry, as some others, require a license to operate. In order to be awarded such a license and to keep it, the company must comply to all requirements, undergo periodic audits and keep record of anything happening along the manufacturing process. This industry is under constant scrutiny of government agencies, regulators, etc.

Therefore, the paperwork associated with products is impressive and requires a lot of resources in the dedicated processes, and as we will see, likely to host a system’s constraint!

Over time, layers of requirements accumulated. And what is a requirement if not a limitation of the way to execute, a constraint?

Quality assurance

Quality assurance (QA), according to wikipedia, comprises administrative and procedural activities implemented in a quality system so that requirements and goals for a product, service or activity will be fulfilled. It is the systematic measurement, comparison with a standard, monitoring of processes and an associated feedback loop that confers error prevention. This can be contrasted with quality control, which is focused on process output.


Anyone working with a Quality Assurance department soon realises that this department is more acting as a defense attorney for the company against regulatory or standardization agencies, and a watchdog internally than a support for improving quality by problem solving.

For obvious reasons, QA and Production must have a clear divide, as it would not be acceptable for the maker to assess and certify the quality of his own production. Their staff are also distinct. QA usually has a huge influence on decisions and can be very powerful, to the point that top executives have to accept QA decisions, especially when QA has to sign off the release of a batch or clear the allowance to ship.

QA activities are mainly administrative, with some lab testing. QA staff is “white collar”, working a typical 9 to 5, 5 days a week regardless of production. Some QA authorizations are mandatory for the physical batch to move to the next step in the process. Many productions run more than one shift, up to 24/7, while QA works 1 shift 5 days a week. As a result, the paperwork relative to production batches accumulate during the QA off-period and is later flushed during QA working time.

Now here comes the first problem. The difference of working time patterns send waves of workload through the system. It is not uncommon for some production batches to wait for QA clearance in front of a process or in a warehouse. This could give the impression that the bottleneck is in the next manufacturing processing step, but it is not.

In reality the bottleneck is in QA. It can be the plain process of reviewing of paperwork or some testing, measurement, analyses, etc. A trivial yet common bottleneck is the “qualified person”, the one or few ones entitled to sign off the documents. Those people, usually managers, are busy in meetings and other work and let the paperwork wait for them.

Note that QA activities are not always extensively described in the production task lists, do not always have allocated time and if they have, QA department is seldom challenged about the staff adhering to standard time neither to possibly reduce the duration by some improvements. This can lead to underestimate the impact of QA’s activities on the production lead time and “forget” to investigate this subject when searching for the bottleneck.

Dependence on third parties

With an ever growing number of requirements to fulfill and proofs, certificates and log files to keep ready in case of inspection, many specialized tests and measurements are farmed out to third parties. It makes sense, in particular if those activities are sporadic, the test equipment expensive and maintenance of skills and qualification for personnel mandatory.

Now this type of subcontracting bears the same risks than any other subcontracting: supplier’s reliability, capability, capacity, responsiveness, etc. and the relative loss of control of the flow as it is now dependent on a distinct organization. The system’s constraint may well be located then outside of the organization, and even beyond its sphere of influence!

Beware of the feeling of being in control when the third party operates in-house. I remember such a case where a specialized agency was doing penetrant inspection and magnetic crack detection in the company. While everything seemed under control, the external experts often failed to come as scheduled because they still were busy elsewhere or had sick leave. When they were in-house, they frequently lost a fair amount of their precious time moving parts around, a kind of activity not requiring their qualification but significantly reducing their availability for high-value added tasks. It turned out that this spot in the factory often was a bottleneck due to the lack of management’s attention.

Where Value Stream Mapping can help finding the constraint

These examples above show that the information flow or paperwork associated to the physical flow can have a significant influence on lead time and can even decide if the flow has to stop.

In such cases Value Stream Mapping (VSM) can help finding the constraint as it describes both physical and information flows on a single map. Note that some companies including Toyota refer to VSM as MIFA, the acronym of Material and Information Flow Analysis.

Without such a map to guide the investigations, people on shop floor may forget to mention (or are not even aware of) analyses, tests, approvals, paperwork review, etc. during interviews of gemba walks. Experienced practitioners will ask about these possibilities when inquiring in strong standard or regulation-constraint environments.

Where the Logical Thinking Process can help

When the system’s constraint remains elusive despite all the search with previously mentioned means, Theory of Constraints’ Thinking Processes or the Logical Thinking Process variant can help finding the culprit by analyzing the Undesirable Effects at system level.

This later approach is best suited for “complex problems” when the constraint is a managerial matter, conflicting objectives, inadequate policies, outdated rules or false assumptions, myths and beliefs.

To learn more about the Logical Thinking Process and the logic tools, see my dedicated pages, series and posts on this blog.

About the Author, Chris HOHMANN

About the Author, Chris HOHMANN

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How to identify the constraint of a system? Part 3

Inventories and Work In Progress (WIP) can be helpful clues to visually identify the bottleneck or constraint in a process, but they can also be insufficient or even misleading as I explained in part 2 of this series.

It is often also necessary to study material and parts routes to really understand where they get stuck and delayed. Chances are that the missing or delayed items are waiting in a queue in front of the constraint. Or have been stolen by another process…

In the search for the system’s constraint, experienced practitioners can somewhat “cut corners” by first identifying the organization’s typology among the 3 generic ones: V, A or T. Each category has a specific structure and a particular set of problems. Being aware of the specific problems and possible remedies for each of the V, A and T categories may speed up the identification of the constraint and improvement of Throughput.

V, A & T in a nutshell

Umble and Srikanth, in their “Synchronous Manufacturing: Principles for World Class Excellence”, published 1990 by Spectrum Pub Co (and still sold today), propose 3 categories of plants based on their “dominant resource/product interactions”. Those 3 categories are called V, A and T.

V, A & T plants

V, A & T plants

Each letter stands for a specific category of organization (factories, in Umble’s and Skrikanth’s book) where the raw materials are supplied mainly at the bottom of the letter and the final products delivered at the top of the letter.


V type plants use few or unique raw material processed to make a large variety of products. V-plants have divergence points where a single product/material is transformed in several distinct products. V-plants are usually highly specialized and use capital-intensive equipment.



You may imagine a furniture factory transforming logs of wood into various types of furniture, food industry transforming milk in various dairy products or a steel mill supplying a large variety of steel products, etc.

The common problems in V-plants are misallocation of material and/or overproduction.

As the products, once gone through a transformation cannot be un-made (impossible to un-coock a product to regain the ingredients), thus if material is misallocated, the time to get the expected product is extended until a new batch is produced.

The misallocated products wait somewhere in the process to meet a future order requiring them or are processed to finished goods and sit in final goods inventory.

The transformation process usually uses huge equipment, not very flexible and running more efficiently with big batches. Going for local optimization (Economic Order Quantity (EOQ) for example) regardless of real orders leads to long lead times and overproduction.

V-plants often have a lot of inventories and poor customer service, especially with regards to On-Time Delivery. A commonly heard complaint is “so many shortages despite so many inventories”.

Misallocations and overproduction before the bottleneck will burden the bottleneck even more. Sales wanting to serve their upset customers often force unplanned production changes, which leads to chaos in planning and amplification of delays (and of the mess).

Identification of the bottleneck should be possible visually: Work In Progress should pile up before the bottleneck while process steps after the bottleneck are idle waiting for material to process.

Note: while the bottleneck is probably a physical resource in a transformation process, the constraint might be a policy, like imposing minimum batch sizes for instance.


A-plants use a large variety of materials / parts / equipment (purchased and) being processed in distinct streams until sub-assembly or final assembly, that make few or a unique product: shipbuilding or motor manufacturing, for example.



Subassembly or final assembly is often waiting for parts or subassemblies because insuring synchronization of all necessary parts for assembly is difficult. Expediters are sent hunting down the missing parts.

Expediting is likely to disrupt the schedule on a machine, a production line, etc. If the wanted part is pushed through the process, it is at the expense of other parts that will be late. The same will repeat as the chaos gets worse.

In order to keep the subassembly and assembly busy, planning is changed according to the available kits. Therefore some orders are completed ahead of time while others are delayed.

The search for the bottleneck(s) starts from subassembly or final assembly based on an analysis of the delays and earlies. Parts and subassemblies that are used in late as well as in early assemblies are not going through the bottleneck. Only parts constantly late will lead to the bottleneck. For those, follows the upstream trail until finding the faulty resources where the queue accumulates.


T type factories have a relatively common base, usually fabrication or assembly of subassemblies and a late customization / variant assembly ending in a large display of finished goods. Subassemblies are made to stock, based on forecasts while final assembly is made to order and in a lesser extend made to stock. In this latter case it’s to keep the system busy even there are no sufficient orders. Assembly is made to stock for the top-selling models.



Computers assembled on-demand for instance use a limited number of components, but their combinations allow a large choice of final goods.

In order to swiftly respond to demand, final assembly generally has excess capacity, therefore the bottleneck is more likely to be found in the lower part – subassemblies – of the T.

The top and bottom of the T-plants are connected via inventories acting as synchronization buffers. The identification of the bottleneck(s) starts at the final assembly with the list of shortages and delayed products. The components or subassemblies with chronic shortages or long delays point to a specific process. The faulty process must then be visited until finding the bottleneck.

Yet bear in mind that assembly cells, lines or shops may “steal” necessary parts or components from others or “cannibalize” i.e. remove parts or subsystems on some products for completing the assembly of others. If this happens, following the trail of missing and delayed parts upstreams can get tricky.

Combinations of V, A and T plants

V, A & T-plants are basic building blocks that can also be combined for more sophisticated categories. For instance a A base with a T on top, typical for consumer electronics. Yet the symptoms and remedies remain the same in each V, A & T category, combined or not.

Wrapping up

As we have seen so far along the 3 parts of this series, the search for the constraint in a system is more an investigation testing several assumption and checking facts before closing in on the culprit.

There are some general rules investigators can follow, like the search for large inventories in front of a resource while the downstream process is depleted of parts or material, but it is not always that obvious.

Knowledge about the V, A & T-plants can also help, without saving the pain of the investigation. And we are still not done in the search for the constraint! There is more to learn in the part 4!

Readers may be somewhat puzzled by my alternate use of the name bottleneck and constraint despite the clear distinction that is to be made between the two. This is because in the investigation stage, it’s not clear if the bottleneck is really the system’s constraint. Therefore, once identified, the critical resource is first qualified as a bottleneck and further investigations will decide if it qualifies for being the system constraint or not.

Bibliography about V, A & T-plants

For more information about V, A and T plants:

  • Try a query on “VAT plants” on the Internet
  • “Synchronous Manufacturing: Principles for World Class Excellence”, Umble and Srikanth, Spectrum Pub Co
  • “Theory of Constraints Handbook”, Cox and Schleier, Mc Graw Hill

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