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Lean Vocabulary Words

Like any other discipline, Lean has its own vocabulary that can seem confusing to many people new to the field. Here is a table of Lean vocabulary words that you might find useful.

5S 5S is workplace organization. Often confused with "cleaning up" and "throwing stuff out", it actually is a systematic way of organizing the workplace and encouraging standard work.

The "S's" are named for 5 Japanese words, beginning with the "S" sound. In English they are: 1) Sort, 2) Set in Order, 3) Shine, 4) Standardize, & 5) Sustain.

For more information, please see the section called 5S.

6-Sigma 6-Sigma is a vast set of tools that helps to reduce variation in a process. The name derives from the term for statistical standard deviation, and our desire to have a process run with +/- 6 standard deviations of the specification limits.

For example, assume we're making automobile pistons, and our tolerance specification is +/- 0.0002 inches on the diameter. A 6-sigma capable process for grinding the cylinder diameter would ensure that no more than 3.4 cylinders in every million are outside this tolerance (when under "normal" manufacturing processes.).

6-Sigma methodology, abbreviated by the acronym DMAIC (Define, Measure, Analyze, Improve, and Control) is a fairly rigid framework for identifying, analyzing, and improving the process to reduce variation. It utilizes a large number of sophisticated statistical tools to determine what creates variation, and this allows us to then development countermeasures to reduce it.

Lean and 6-Sigma (often abbreviated LSS) are separate, but highly complementary disciplines.

For more information, please see the section called 6-Sigma.

7 Deadly Wastes Lean practitioners have determined that waste always falls into 7 categories, and have declared these to be the "7 deadly wastes". These types of waste include the familiar (scrap & rework), but also the unfamiliar like "overproduction".

The wastes are: 1) Defects, 2) Overproduction, 3) Waiting, 4) Inventory, 5) Extra Processing, 6) Conveyance, & 7) Motion. In addition, I always add the most important form of waste: 8) Unused Human Ingenuity.

One key Lean concept is that waste has to be identified before it can be eliminated. In fact, you often find that people often go to extraordinary efforts to hide waste.

Lean tools try to make waste glaringly - even painfully - obvious. It is only by recognizing this waste that we have a chance of eliminating it.

For more information, please see the section called The 7 Deadly Wastes.

Andon Cord An Andon Cord is like an emergency brake on an old passenger train. Pulling the cord stops the process and sounds an alarm. The cord is placed so that associates can halt a manufacturing process if there is a problem they cannot solve. This stops the process and sounds an alarm to bring additional help.

Andon cords were popularized by Japanese automobile manufacturers who found that their assembly lines ran more smoothly if each assembly worker had the authority to stop the line. This meant that problems were dealt with quickly rather than being allowed to fester for a long period of time.

Andon Light An Andon Light signals the status of a work place. In its most basic form, it is a Red/Yellow/Green light assembly. If the process is running well, the green lights are on. If the associate running the operation has trouble, he may turn on the yellow or Red lights, to indicate he needs assistance to resolve an issue.

Autonomation Autonomation is sometimes called "intelligent automation". It is automation with an automatic fault detection that shuts down the process when a fault or non-conforming result occurs. This allows us to get the manpower-saving benefits of automation, without worrying about producing non-conforming products undetected.

Black Belt A Black Belt is someone who has been trained in sophisticated Lean Six-Sigma (LSS) methodology. Typically, this is approximately 120 hours of classroom time, and completion and presentation of a project which utilizes these skills and saves in excess of $100,000.

A Black Belt is also considered a permanent trainer and mentor to others in the organization. He should be constantly explaining and helping other to utilize the Black Belt tools.

Unfortunately, there is no governing body that establishes credentials for a Black Belt. Several large professional organizations, such as the Society of Quality Engineers, and the Society of Manufacturing Engineers, have established certification procedures that appear to be very good. However, this means you can never be sure how much a "Black Belt" really knows unless you test him.

Buffer Stock Buffer Stock is inventory kept on hand to "buffer" variation in output or demand. Since it is often very difficult to perfectly synchronize operations, we generally need some type of buffer between those operations. Also, since variations in cycle time, process yield, and customer demand may change the actual output rate from day to day, we utilize buffer stock to smooth out those variations.

We would like for Buffer Stock to be as small as possible. In a perfect world, this stock would be zero. As a process becomes better and reduces these types of variation, it is possible to reduce the buffer stock.

Buffer Stock is very similar to Safety Stock, except that it is kept to allow for minor variations in the supply chain instead of catastrophic events such as missed supplier deliveries or major machine malfunctions.

Setup Time
Changeover Time
Setup or Changeover time is the amount of time the equipment is not making parts. It starts when the last good piece is finished, and doesn't end until we have made the first good piece.

People often find that the most of the work of a changeover proceeds quickly, but the process needs a lengthy series of adjustments and trial runs before a good piece is finally made.

SMED principles are often used to reduce changeover time.


Project Charter
A Charter is a formal definition of a project. This is the most critical (and usually most overlooked!) part of the Lean problem solving methodology. While we may think we understand the problem, the potential solutions, and the overall approach to solving the problem, in actuality, it is very common for us to have only a cursory understanding of these things. A poorly defined project has a much lower probability of success, and will take a lot longer to complete than a well-documented project.

The project charter includes a formal definition of the problem (which is surprisingly difficult to write), as well as a justification for doing the project. It also will outline the expected completion dates, and the resources (both capital and human) needed.

One major portion of the charter is the "Scope". The scope defines what is included in the project, and more importantly, what is not included. Projects often suffer from "scope creep" where the boundaries of the work expands during the course of executing the project. When this happens, it makes it much more difficult to complete the project on time with the allocated resources. A well defined scope, agreed to by management, makes this creep much less likely.

Cycle Time Cycle time is very straightforward. It is the amount of time it takes to produce something. We have always been concerned with this time because we have traditionally thought that longer cycle times equal higher costs. (In a Lean world, we know that this is not necessarily true.)

Ideally, Cycle Time should exactly equal Takt Time. However, in the real world, we want the Cycle Time to be slightly shorter than the Takt Time so that any disruptions in our internal processes do not impact the customer and leave him without product.

("Pitch Boards")
A Day-by-the-Hour board (also sometimes known as a "Pitch Board") is one of the most powerful (and underutilized) Lean tools available. This technique has the process operator stop briefly each hour and record how many widgets they ran during that hour. This is compared to a standard established by the manager. This means that the operator knows how he is performing against standard every hour of the day.

The goal for each hour is adjusted based on the product being run and the actual working time for that hour. Therefore the goal is half the normal rate for the hour where the associate gets a half-hour lunch break.

Managers must regularly and publicly review the board. They praise the associate if they meet or exceeded the goal, and do troubleshooting to find out why the goal was not met.

This system prevents the "lost hour" phenomenon where a problem slows production for an hour or more and no one knows the problem is occurring.

The use of the board itself can improve productivity by over 10%.

For more information, please see the section called Day-by-the-Hour Boards.

You can download an short training course on Day-by-the-Hour boards here.

DMAIC DMAIC stands for Define, Measure, Analyze, Improve, and Control. The DMAIC process is the basis for all 6-Sigma projects.

First Pass Yield First Pass Yield is the percentage of products that meet specifications without requiring any rework. Most manufacturing plants work very hard to get as many good products out the door as possible, and expend lots of time and energy reworking non-conforming products.

In a Lean world, we detest the "Deadly Waste" of Processing. Every hour spent reworking products saves a few products for that day. But every hour preventing rework by solving the root cause pays off forever.

Don't fall into the rework trap! Spend your energy finding the root cause of problems and solving them.

Gemba Gemba is a Japanese word referring to where actual work is done. This typically means the factory floor (as opposed to the manager's office). If you want to find out what is really happening in your operation, you must "go to Gemba".

Gemba Walk Gemba Walk is a formalized process used by managers to visit the factory and find out what's really going on. It is a scheduled activity where the managers visit each work area. They observe the operation and review posted metrics on how well the area is performing.

The managers are able to see the operating results (from the Visual Metrics) and they can offer praise, advice, or direction to operating associates.

Gemba walks have 3 profound benefits:

  1. Managers get out of the office and really find out what's happening. They become truly involved in a way that they may not otherwise.
  2. They martial all the available resources needed to quickly solve routine problems.
  3. They allow the management team to be seen as interacting and being involved.
This second benefit, while entirely psychological, is very powerful. If the boss is interested in a department's results, the operating associates are more likely to be interested also.

For more information, please see the section called Gemba Walk.

Green Belt A Green Belt is someone who has been trained in basic Lean/Six-Sigma methodology. Typically, this is approximately 40 hours of classroom time, and completion of a project which utilizes these skills. The Green Belt is the lowest of the "belts".

Unfortunately, there is no governing body that establishes credentials for a Green Belt. That means you can never be sure how much a "Green Belt" really knows unless you test him.

The next higher level is Black Belt.

Heijunka Box A Heijunka box is a simple, visual method of scheduling work that puts a great deal of clearly defined scheduling authority into the hands of the associates running the operation. Heijunka boxes are difficult to describe in words, but easy to see.

Heijunka boxes provide many great benefits. They are simple and visual; they put final scheduling control at the operation; they are very flexible.

Herbie A Herbie is the slowest operation in a process. It is the bottleneck operation that limits the total output of the process.

The name comes from the classic book "The Goal" by Goldratt. In the book, the Hero is leading a troop of boy scouts on a hike, and discovers that the entire troop's progress is held back by Herbie, the slowest hiker of the troop. The Hero discovers that it does not matter how fast any of the other scouts can hike, the entire troop will be held back by the slowest boy (the "Herbie").

Manufacturing engineers often fall into the trap of trying to speed up all the operations in a value stream, when in fact, only the bottleneck's (the "Herbie") production rate will actually have a profound effect on output.

Hoshin Kanri
(Policy Function Deployment)
Hoshin Kanri is a method by which all of the associates in an organization are focused on the same goals. It attempts to bridge the (sometimes wide) gulf between an organization's overall strategy and the daily activities of its members.

The words are Japanese for the needle of a compass and for managerial control. (Think of a fleet of old ships, with all their compasses pointed north, all moving in the same direction.)

Hoshin Kanri is therefore how management sets an overall direction, and the entire organization strives to move in that direction on a daily basis.

Some organizations use the obtusely named "Policy Function Deployment" to achieve this same objective.

Kaizen Blitz A Kaizen Blitz is a method for making a rapid change to a small, focused area or operation. Kaizen is taken from the Japanese words meaning "Kai" ("Change") and "Zen" (the Pinnacle or best). "Blitz" is taken from the German name for "Lightning" or "rapid", so a Kaizen Blitz is a rapid change for the better.

Kaizen Blitzes have a very specific methodology which involves training associates, executing the improvements, and then presenting those improvements to the rest of the organization.

A Blitz will typically last 3 - 5 days, although very small, focused blitzes can be done in just a few hours.

For more information, please see the section called Kaizen Blitz.

Kan Ban A Kan Ban is literally a signal for someone to take an action such as running an order or moving some materials. The signal often takes the form of a card or light, but can be any type of easily used signal. Generally, we like these signals to be as visual and obvious as possible.

A visual Kan Ban can also be an integral part of a Visual Factory.

Lean/Six-Sigma is a shorthand method of referencing the Lean and 6-Sigma methodologies. While they are separate disciplines, they complement each other very well and are often taught as a single course of study. Lean emphasizes the elimination of waste, and tends to be very visual. 6-Sigma emphasizes the elimination of variation (which is generally a cause of waste) and tends to be mathematical.

6-Sigma methodology is based on the DMAIC process.

For more information, please see the section called 6-Sigma.

Line Balancing Line Balancing refers to shifting work elements from one person to another, so that we can potentially reduce total labor. It takes advantage of idle time embedded in each person's work tasks.

Our objective is not to equalize the load on everyone. Instead, it is to fully load (but not overload) as many people as possible and create large blocks of idle time which we may use to reduce headcount or fill with other value-added work.

Master Black Belt The Master Black belt is the PhD of the "belts".

He is a Black Belt with extensive and wide experience in using Black Belt methodology. Some people believe a MBBs knowledge should be "deep", while others believe that a breadth of knowledge and ability to apply LSS methodology to a wide variety of real work problems truly defines the Master Black Belt.

Like the other belts, no governing body exists which establishes credentials for a Master Black Belt.

Muda Muda is the Japanese word for waste. In a Lean world, we've classified waste into 7 Deadly Waste types. A Lean environment tries to make Muda obvious, so that we have a better chance of eliminating it.

Overall Equipment Effectiveness
OEE is a measure of how effective a piece of equipment is. It is the mathematical product of the percent of full speed the machine can run, times the good quality yield, times the uptime of the machine.

OEE = (% Speed) * (Quality Yield %) * (Uptime %)

Percent of Full Speed refers to the current speed of the machine compared to the speed of a machine in perfect operating condition. If wear on the machine has forced the machine to be run slower so that it makes good product, then this percentage is reduced.

Quality Yield is the percentage of good products made on this machine. Defects caused by poor materials or operator errors should not count, since we are only concerned with the machine itself.

Uptime is the percentage of time the machine runs, when you want it to run. Don't count time the machine is scheduled to be down for maintenance or lack of work.

Organizations often think they have a full machine, but find that due to mechanical wear and tear, they have much less than a fully functional machine. The OEE indicates mathematically what percentage of a good machine you have.

While simple in practice, actually gathering accurate OEE data can be quite burdensome from a record-keeping standpoint. Many organizations short-cut this process and use OEE only as a relative measure of performance. They look for changes in OEE rather than the actual OEE itself. This reduces the value of the calculation slightly, but this trade-off is probably still acceptable if it lets an organization understand how equipment problems are hurting their performance.

Poke Yoke
(Error Proofing)
Poke Yoke is the Japanese phrase for "error proofing". A poke Yoke device will halt the process rather than allow a non-conforming product be produced. By its very nature, it forces us to stop and fix the problem before we continue.

Rework is completely anathema to Lean practitioners, and a Poke Yoke system forces us to fix the problem rather than simply "live with it" and do rework.

A common example of a poke yoke in your everyday life is the fuse box in your basement. We would rather have you be greatly unconvinced with a power failure than allow an electrical overload to cause a fire. While the blown fuse is very inconvenient (especially when the big game is on TV!), it is preferable to allowing us to lose our house in a big fire. A blown fuse is absolutely unforgiving; we must fix the overload before we can do anything else.

Policy Function Deployment
(Hoshin Kanri)
Policy Function Deployment is a method by which all of the associates in an organization are focused on the same goals. It attempts to bridge the (sometimes wide) gulf between an organization's overall strategy and the daily activities of its members.

This unwieldy phrase is similar to the Japanese phrase Hoshin Kanri, for the needle of a compass and for managerial control. (Think of a fleet of old ships, with all their compasses pointed north, all moving in the same direction.)

Some organizations use the Japanese name "Hoshin" or "Hoshin Kanri" to achieve this same objective.

Pull System A Pull System is the opposite of "push" system. In a Pull System, downstream operations "pull" materials from the upstream operations.

For example, if a company is fabricating metal parts and then does a final painting operation, the fabricating department is prevented from fabricating more parts until the last parts have been painted. This prevents a buildup of parts at the painting operation, and makes the material flow more efficiently through the factory.

Pull systems represent a fundamental change in how an operation is managed on a daily basis. Instead of scheduling each operation to run, and then hoping they run the expected products on time, we schedule a single point in the process, and let the later operations pull products from the earlier operations. In this way, we create a much stronger customer/supplier relationship between sequential operations. We like this customer/supplier relationship because it helps clearly establish requirements and tends to make each more efficient than it would be otherwise.

Pull systems often are part of a Supermarket system.

Red Tag System A companion to the 5S process, the Red Tag System helps to remove unnecessary items from the workplace.

During a 5S event, people often find valuable items (such as furniture, equipment, or supplies) that are not needed in the immediate area, but might be useful somewhere elsewhere in the organization. Normally, we are ruthless about disposing of unneeded items, and using the Red Tag process allows us to remove them from our workplace while at the same time making sure that someone else doesn't need them.

The Red Tag process works by placing red-colored tags on unneeded items. On the tag we write the name of the person who does not want the object, as well as the date that they tagged it. These items are then moved to a special, public space where everyone can see the items. If anyone else in the organization has a use for a tagged item, they may take it. However, if no one takes the object after 30 days or so in the Red Tag Area, it is disposed of.

For more information, please see the section called 5S.

Safety Stock Safety Stock is very similar to Buffer Stock, except that it is for kept as insurance against catastrophic events such as missed supplier deliveries or major machine malfunctions.

The stock itself is indistinguishable from Buffer stock, but the reasons for keeping it are due to the things in the "act of God" category instead of the "variation" category.

(Quick Setup)
SMED stands for Single Minute Exchange of Dies. It references the ability to make a process changeover (or setup) in less than 10 minutes. The techniques were pioneered by Toyota for their very large stamping presses that used to take days to set up, and can now be done in minutes.

SMED involves moving tasks from "internal" (when the process is down) to "external" (when the process is still running). In other words, we try to do as much work for the setup as possible while the process is still running, so that we minimize the downtime.

We also work very hard to eliminate adjustments to the process. In our Lean world, we want to install new tooling, change a few dials, and then immediately make good products.

Supermarket Named after the supermarket that we are all familiar with, it is used in a Pull System to limit overproduction and allow flexibility to the downstream operations. In a pull system, production is triggered by the demand of the downstream operation. A Supermarket makes this demand easy to see because it opens space for the upstream operation to fill.

In a supermarket there is a dedicated and limited space for a particular product. Once that product space is filled, no more of that product can be produced until the space is opened up by having a customer remove the product when he purchases it.

The customer can take any product he likes off the supermarket shelf, but the producer can only produce a product if there is a space available to take it. This effectively prevents the waste of of overproduction.

The determination of the amount of space to keep on the shelf can be a complex calculation involving the rate the customers take the product (the Takt time), the production cycle time, and the variability of both.

Takt Time Takt Time is the rate that the customer wants his products. Usually expressed in units of minutes or seconds, it is meaningful because it allows us to create a process which satisfies the customer's demand without overproducing.

"Takt" is the German word for "Beat" or "rhythm". It becomes our metronome.

For example, customers log on to your website and purchase 312 Green Widgets and 27 Red Widgets every day. If your Widget factory runs a single 8-hour shift, then the Takt Time for Green Widgets is:

8 * 60
312 Green Widgets

1.54 minutes / Green Widget

And the Takt Time for Red Widget is:

8 * 60
27 Red Widgets

17.78 minutes / Red Widget

We therefore want our Widget factory to be able to produce 1 green Widget every 1.54 minutes and 1 Red widget every 17.78 minutes. (If they are made on the same equipment, then our total widget Takt time is 1 widget every 1.42 minutes).

We often have trouble with the Takt time because it changes from hour to hour and day to day due to changes in our sales to the customer. Ideally, we change our production rate to exactly match the Takt Time. If the Takt changes too often, we typically take an average Takt time over some period and match the average. We must always be aware that the Takt can (and will!) change, forcing us to adjust our production rate.

Value We have a very simple, yet profound definition for "Value" in the Lean world. Very simply,

"Value" is anything the customer will pay for.

If the customer is willing to pay you for it, it is valuable. If he is not willing to pay, then it has no value.

For example, we don't put industrial products in expensive, glossy packaging since the industrial customer place no value on anything other than protecting product integrity. Consumers shopping in supermarkets, however, place a great deal of value on "shelf appeal" and are willing (if often unconsciously) to pay for expensive packaging and image branding.

The truly horrifying thing to realize about value is how much of our time we spend doing things our customers do not want to pay for. This gives us great opportunity, however, to minimize those non-valuable things and spend more time doing things he will pay for.

Visual Factory "Visual Factory" is a catch-all term that refers to an environment where it is easy to see the status of the operation, as well as the correct way of doing things. A Visual Factory will be very well 5S'd, have posted work instructions, and excellent visual metrics.

For more information, please see the section called Visual Factory.

Visual Metrics Visual Metrics are the presentation of performance measurements in a very public (visual) way. It is a truism that whatever you measure gets better. By publicly posting the results of productivity or other important measures, we drive better performance.

For more information, please see the section called Visual Metrics.

What Does Good Look Like?
A description of what the world would look like if the problem we're facing was corrected. It is the opposite of "The Problem".

One of the most surprisingly difficult aspects to solving a problem is actually defining what that problem really is. People who have trouble defining a problem will also have a great deal of difficulty solving it. WDGLL is part of this problem definition process.

Typically, a Lean project will start with a "Charter" that defines many things, including "the Problem", and its opposite, WDGLL.

A WDGLL must be written in clear, grammatically correct sentences. If you cannot define WDGLL in clear sentences, then you really don't understand what you're trying to do, and therefore, you will never accomplish your goal.