Is A Mistake Free Environment Possible?

Wouldn’t it be grand to have a process that runs ‘mistake proof’? For most, the idea of a mistake proof environment is business heaven. The real world tells us that mistakes and errors are all part of life and business. The idea is to have processes and procedures in place that reduce or eliminate mistakes. Mistake proofing, or its Japanese equivalent poka-yoke (pronounced PO-ka yo-KAY), is the use of any automatic device or process that either makes it impossible for an error to occur or makes the error immediately obvious once it has occurred. This is a method at the disposal of Lean Six Sigma practitioners to reduce and eliminate errors in process and procedures.

The Elements of Poka-Yoke

Like with any other tool in Lean Six Sigma, there are some steps you need to follow to get the most out of mistake proofing your projects. Here are the 7 steps that are crucial for implementation of mistake proofing:

1. Create a flowchart. Think about where errors will occur.
2. Identify the source or origin of each mistake.
3. Identify ways to prevent the errors from occurring.
4. Consider mitigation methods for errors that cannot be eliminated.
5. Identify the best method for mistake-proofing the process or device.
6. Inspect for errors by setting functions.
7. Set signals that alert workers for errors with regulatory functions.

Factors to Consider With Poka-Yoke

We sometimes depend on inspections conducted by workers to be fail safe for mistake proofing. While this does have some validity, humans are flawed and naturally prone to errors, even to the smallest degree. We can overcome these inspection defects through automation of the process. Automation will not accept a defect in the process, or create a defect in the process, or allow a defect to be passed to the next process. As with any other process, you must consider the cost of implementing poka-yoke mistake proofing methods. When determining the value of poka-yoke, you then must consider these expenses vs. the financial impact of defects reaching your customers.

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The Toyota Production System, I argue, appreciates the individual and empowers the individual to improve her work within the System; by doing so, a firm can increase its ratio of problem-solvers to problem-finders.   But, this article is not about Taylorism versus The Toyota Production System — ignoring my propensity towards tangents for a moment — this article is about Root Cause Analysis, Genchi Genbutsu, and Human-Centered Design — all elements I found in the book Better: A Surgeon’s Notes on Performance, by Atul Gawande. Or, more simply put, Lean for Healthcare.

I recently read a short excerpt from the book Better: A Surgeon’s Notes on Performance, by Atul Gawande, which is an excellent example illustrating the relationship between Root Cause Analysis, Genchi Genbutsu, and Design.   The book is a series of essays that explain, with heart-felt candor, how difficult it is to be a physician and also points out the weaknesses and vulnerabilities of the system, the physicians, and its impact on the rest of us.

Eye Injuries & Poor Design

In the excerpt that I read today, battlefield physicians noticed that soldiers and marines were getting a lot of eye injuries.  They physicians asked the patients why they weren’t wearing their protective eye coverings.  The answer? — The soldiers didn’t want to look like dorks!  This point may seem subtle, but is a critically important one: These are soldiers on the front-lines, facing death everyday.  Any amount of humanity — even vanity — that they can hold on to is important to them.  Part of good, human-centered design is that the product must be elegant — in it’s design and functionality.

So, the goggles were redesigned to look like cool sunglasses, and the eye injury rate went down.  This is also a great example of why you need to ask users about problems with products.

This is also an example of Poka-Yoke: to mistake proof our systems, processes, and devices.

Conclusion

In conclusion, we see the physicians quickly arriving at the Root Cause of eye injuries.  They “went and saw” for themselves by asking the patients themselves why they weren’t wearing the protective goggles.  Then, the practical solution was to redesign the goggles to make them more attractive.  The result? — reduced battlefield eye injuries and cooler-looking sunglasses.

I’ve already ordered the book.  I can’t wait to read it.

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Statistically, zero defects means a defect level of infinity sigma, which is not possible.  What most people mean, is an attitude toward process improvement — relentlessly improving the way we do things, the product or service we produce, in order to continually delight the customer.  That is really what people mean.  But, but the “zero defects” sloganeering gets in the way.

Are All Defects The Same?

The “Zero Defects” movement has an implicit assumption that all defects are equal.  This is not true.  In fact, for most firms and products, defects must be identified and prioritized, and attacked and treated from most important to least important.  For the defects at the bottom of that prioritized list, it might even make sense to move on and not eliminate or reduce those.  The point here is an attitude toward perfection, but fully understanding that perfection is not possible.  The attitude and efforts are valuable and the customer will feel and appreciate it.  Shareholders will benefit, and the firm will be better for it.

Types of Costs

There are three types of costs that comprise the cost of quality: Appraisal, Preventative, and Failure costs.

Appraisal Costs

The costs in this category includes any and all activities in identifying and assessing for errors or defects in products.  For example, testing is an activity that falls in this category; a department that might fall in this category is the Quality Assurance department ” this department’s burden would fall under the Appraisal Costs category.

Preventative Costs

The activities that fall under this cost category are training, and any and all activities the encourage prevention or discourages introduction of defects.  Establishing processes, procedures, and systems prior to the product being built is typically found in this category.  Money spent in this category is money well-spent!

Failure Costs

Failure costs can be both Internal and External.  Internal Failure Costs can be money spent to fix defects caught within the firm.  For a software firm, money spent on fixing bugs caught prior to shipping a product can fall in the internal failure costs category.  For External Failure Costs, these are activities that involve refunds, complaints, call center functions (not outbound sales, but inbound complaints), concessions to the customer for poor service, and warrantees.

Zero Defects and Costs

I present below what I believe to be the relationship between costs and defects:

On the X-axis, we see the costs category (just use a dollar multiplier for the X tick marks).  On the Y-axis, we see defects, by count.  So, we see that as defects approach zero, costs increases exponentially and hovers asymptotically on the x-axis, and never reaches zero.

Footnote:  The costs to a firm where there is no effort to identify and reduce errors or defects can also be exponential.  For example, imagine a firm where there was no inspection, appraisal, or prevention of faulty, defective, or harmful medical devices or drugs.  The external failure costs alone could bring the firm to bankruptcy.   I recognize this fact, but wanted to make a point above regarding zero defects.

Why is the above Graph True?

As defects are identified and eliminated, there will be theoretically few defects.  But, this means that identifying defects will require more effort and will become more and more difficult, thus increasing the costs of this activity, along with the subsequent costs to fix the defects identified: The costs to inspect and test increases as there are fewer and fewer defects.

A Caveat & Poka-Yoke

As defects are reduced, the Appraisal cost increase — that is, the cost to detect a defect grows.  There is a trade-off.  One very effective way is to implement Poka-Yoke: to mistake-proof our processes and prevent service or product defects all-together.

Conclusion

Sloganeering doesn’t help, especially if the slogan makes no sense.  “Zero Defects” as a mantra has a nice cumbaya ring to it, but doesn’t really help or motivate a crew to do better.  Moreover, “Zero Defects” is statistically impossible as well as cost prohibitive.

Regarding defects: not all defects are equal.  It is important to identify the defects that impact the customer, prioritize those, then respond in a prudent way in improving the product or process.  Going after all defects is not prudent.

The key takeaway here is the following: strive to be better everyday; strive to make the customer happy.  The Firm’s efforts to make the customer happy will be felt, a culture of improvement will be created, and the firm and shareholders will benefit from it.

The post Everyday Poka-Yoke: Cost of Poor Quality appeared first on 6sigma.

We have many process analysis tools in Lean, but the poka-yoke is one of the most popular ones. In any given process with human operators, mistakes and errors are bound to happen. These lead to defects, which are part of the eight wastes of lean. Poka-yoke, also known as mistake- and error-proofing, helps eliminate mistakes entirely.

We will discuss what poka-yoka – pronounced as poh-kah yoh-keh – is, its history, the benefits and some examples. This should briefly introduce you to the concept and why it is useful. While it is mostly used in the manufacturing and service industry, its application is universal.

What is Poka-Yoke?

Poka-yoke is an automatic mechanism, whether it is a device or method, that prevents anyone from making a mistake or error. But if the mistake or error can’t be prevented, a poka-yoke will make it obvious that it has occurred. That way, the source can be identified and eliminated.

A Brief History of Poka-Yoke

The person who coined poka-yoke is Shigeo Shingo in 1960. He was a Japanese industrial engineer who worked for Toyota. Shingo was one of the top experts on manufacturing practices at the time. And apart from the poka-yoke, he is mostly known for standardizing the Toyota Production System (TPS), which is a popular manufacturing methodology for eliminating waste and increasing efficiency.

The term poka-yoke itself literally means “mistake-proofing.” Interestingly enough, it was originally called baka-yoke or “fool proofing.” But it was later changed, considering it had negative connotations and the Japanese have a culture that highly favors politeness.

The Benefits of Poka-Yoke

One of the biggest benefits of poka-yoke is that it minimizes the chance of human error in a process. It ensures that all conditions are right before the next step in the process occurs. The end result is that the process will produce little to no defects.

Other than that, poka-yoke also comes with the following other benefits: 

• Increase in quality: With the poka-yoke making sure that the process doesn’t produce defects, the quality goes up. This means stakeholder and customer satisfaction goes up as confidence levels in your process consistently producing quality products increases.
• Reduction in costs: The biggest problem with defective products is that they increase the amount of waste. And since they need to be replaced, the costs of production rises as the number of defects rise as well. Fewer defects mean fewer costs.
• No high-skill requirement: if a process has a bigger margin for error, it needs operators to be highly skilled to operate it. If the operator doesn’t have the skill, the organization has to spend resources to either train them or hire a more skilled worker. With a poka-yoke automatically preventing mistakes and errors, the skill requirement goes down significantly.
• Increases safety: Safety is a major concern in the workplace, especially when workers handle hazardous materials. With poka-yoke eliminating human error, safety in the workplace goes up by a great margin.
• Reduces the need for quality checks: With an error-eliminating device or method embedded into the process, there’s no need for extensive quality checks. The poka-yoke will detect or predict any problems without relying too much on inspectors.
• Speeds up the process: With less manual inspections needed, work progresses at a faster rate without sacrificing quality. Moreover, the workers focus on what they do best, which makes the work less boring and repetitive.

Example of a Poka-Yoke

You don’t need to go far to see an example of a poka-yoke – they are around us all the time. One example is charging your phone with a USB. When you try to plug it in the wrong way, the USB does not enter. It only enters when you flip it and plug it in the right way.

Another famous example is the automatic car. Manual cars allow you to start your car while in gear, but in doing so the car will move and accidents can happen. An automatic car, however, will not start unless it is in neutral or park – hence eliminating the error.

Conclusion

With poka-yoke, mistake-proofing is built into the process, significantly reducing or eliminating human error. While we’d all like things to go smoothly all the time, when humans are involved things can go wrong. This is why the poka-yoke has become one of the most popular process analysis tools in Lean.

The post Mistake and Error Proofing: Poka Yoke appeared first on 6sigma.

Thinking One Step Ahead with SMED

Proper optimization is not just about making the facility run well with the current parameters in mind, but also to allow it to run as efficiently as possible in the future, considering upcoming developments. You have to always be one step ahead of the current environment and make informed strategical decisions.

SMED stands for Single-Minute Exchange of Die, and it refers to a methodology for improving the processing rate of a manufacturing plant. It achieves that by streamlining the process of switching from one product to the next one in line, and ensuring that all of your machines keep running at optimal efficiency at all times. It can also be used in an office setting, such as switching from task to task.

From a lean perspective, we want to complete tasks one at a time. When we batch our work, it’s often a result of the time required to changeover from product to product, or task to task. SMED can help us reduce the changeover time, to make it more efficient to operate in smaller batches.

SMED is also referred to as changeover reduction.

Going in depth

There are many intricate details to SMED.  It’s a more general term referring to the process of changing targets within your work. The name of the methodology also comes from the fact that Toyota, in the past, identified larger dies as the most problematic objects in their manufacturing chain. Dies in an office setting could be a software program that takes time to load.

Changeover times are often responsible for the biggest slowdowns in productivity, and that streamlining the process of switching work could have dramatic effects on the overall output of the business.

It’s also important to note that single-minute refers to the idea that those “exchanges” should occur in a single-digit minute (0-9 minutes), not necessarily in sixty seconds. Anything up to about ten minutes is okay in the eyes of SMED, although of course the specific time is going to vary from one company to another.

SMED and continuous improvement

SMED goes hand in hand with continuous improvement, as it can allow you to always seek to maximize the potential capacity of the organization. It’s a technique that can be applied regardless of the specific current situation, making it highly flexible and suitable for incremental upgrades. What’s more, SMED can ensure that an organization running with more advanced modern technology is always utilizing that technology to its full potential, looking for opportunities to improve its output.

What exactly should you do to implement SMED though? There are several main components to the methodology, and the exact way of using it is going to vary across the board. The general idea is to ensure that there is a clear separation of internal and external setup, so that the state of the machines or computer systems can be reset as quickly as possible.

• Internal Setup – Time spent in changeover when the machine or system is idle
• External Setup – Time spent in changeover when the machine is working on something else

For example, when you look at the time to changeover your work, how much could be done while you’re finishing up the last job or project? Could someone else be getting the next item ready to go? Getting these tasks started earlier is an example of moving from internal to external setup.

In addition, the creator of SMED states that it’s important to focus on standardizing the functionality of the company’s machines and systems, not the specific output they’re producing. In a manufacturing setting, clamps should be functional, or alternatively fasteners should be removed completely if that’s not possible. This reduces the actual time to complete the task.

Introducing some additional intermediate steps in the process can also have a positive effect on the overall performance. Sometimes the lack of buffer zones can be a major contributing factor to performance issues, and 5S is a great method to ensure that those problems don’t go unnoticed.

Last but not least, there is also a strong suggestion that the company should look into automating as much as possible from its current range of tasks. This is an obvious one in many industries, especially auto manufacturing where SMED is rooted. Priority should be placed on the internal setup tasks that slow down the overall changeover time.

Conclusion

SMED can be a great way to always have a good edge in your company. It’s a flexible technique that can be highly useful to a variety of different organizations, and it’s also aligned with the current trends in technology and the direction we’re moving towards for the future. There are some clearly valuable lessons to be learned from SMED, and every leader should make it a point to familiarize themselves with the principles behind it as early as they can in their career.

Learn more about SMED >>>

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Many years ago, I had to travel to Dublin every few months for work. I had team members there and part of my responsibility was to be a good leader and spend time with face to face. I was living in Salt Lake City at the time and it was a pleasure to spend time with them, even though it took me away from my family every few months or so.

One very early morning while waiting for the taxi to pick me up at my hotel to take us to the airport, my colleague with whom I was traveling with at the time had ordered coffee while I ordered a Coke since I’m not a coffee drinker. They brought him his coffee in this cup.

At first glance, I thought to myself “Wow, that’s a fancy cup” because, in America, cups mainly look like, well, cups. This, on the other hand, was no ordinary cup – this was a fancy European cup.

But, wait. Take a closer look. Do you see any problems?

Let me tell you my friend’s experience. Perhaps you’ll see the issues as I tell you his ordeal.

• When my friend stirred the spoon, it hit the bumps on the inside of the cup.
• The handle is a not really a handle that allows your fingers to securely hold the cup. Instead the handle is a ceramic stub, forcing my friend to use every muscle available in his thumb and forefinger to hold this fancy coffee cup.
• The handle has a little well, allowing the coffee to occupy the space. Coffee is hot. And, hot coffee on a handle where your thumb and forefinger is means you will burn yourself with every courageous attempt at a sip of coffee.

Here’s another picture to see what I mean:

Poka Yoke, Human Errors

For practitioners of Lean and Six Sigma, we know that Poka Yoke means error proof or designing our processes, products, and systems in a way that helps to prevent errors. But what many of us, I think, underestimate the power of poor design and how it invites us to make errors without us even realizing it.

The System: Organization, Team, Individual

Moving from a product context to a service context, design can occur at, I believe, 3 levels: the organization, the team, and the individual. Let me use a case study to explain.

Back in 1999, a seminal paper entitled [1. I haven’t read the entire report, but I plan on doing so.] To Err Is Human: Building a Safer Healthcare System by Kohn, et al, examined the state of the healthcare system. The numbers the authors presented shook the industry. They reported that 44,000 people died in US hospitals every year from preventable medical errors. They estimate that number could be up to 98,000. Even at the lower estimate of 44,000, deaths from preventable medical errors were higher than the mortality rate of breast cancer and HIV/AIDS.

This finding shook the industry and led to many patient safety initiatives thereafter.

But the authors made one very significant conclusion that perhaps received the most scrutiny because it flew against the commonly held belief that human errors were due to personal recklessness and general sloppiness in the delivery of care from healthcare professionals [2. My good friend Mark Graban – I’m sure – could share many stories from his work in improving healthcare. If you’re a healthcare professional, check out Mark. They guy is all about improving healthcare. I’ve learned a ton from him.]. That conclusion was this:

The majority of medical errors did not result from individual recklessness, but instead were caused by faulty systems, processes, and conditions that led people to make mistakes or failed to prevent them.

In other words, pointing the finger at individuals for mistakes made is not the entire story. Perhaps we need to look into the design of the systems, processes, and the conditions that led to the errors also.

Back to the Coffee Cup

Suppose my friend burned his hand. He didn’t, but let’s suppose he spilled his coffee that morning and burned his hand. Knowing him, he would’ve blamed himself. He would called himself stupid. He would’ve felt like spilling the coffee and burning himself was all his fault.

Would he be right?

NO.

The design of our systems, processes, and the conditions that led to the event have everything to do with whether human errors are made or not. Just like looking at the poor design of the coffee cup brings insight into why coffee is easier to spill and burn the person holding the cup, looking into the design of systems, processes, and the conditions that led to the error will also bring the same insight and allow us to make longer lasting improvements that may truly prevent human errors.

The post What a Coffee Cup Taught Me About Poka Yoke and Human Errors appeared first on 6sigma.

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The point is this: if you’re eating more than your body needs, you’re overproducing and getting more calories than you need. The result? You’ll probably gain weight. Interestingly, Facebook knows all about this and has come up with an interesting way to mistake-proof the eating process [1. source: http://mashable.com/2012/04/07/facebook-hq/#57853Facebook-Food].

Facebook is growing and is in need of expanding their Headquarters. And, they’ve needed to look at their approach for providing free food to their employees, a perk that Facebook employees really love. But, how do they avoid the behavior that almost always comes with anything “free” attached to it, especially “free food”?

What do you see in the picture below? Or, more accurate, what don’t you see? Notice there is no tray — Facebook thinks you’ll eat too much unless you only carry a plate. In other words, this is a way to Poka-Yoke the waste of overeating.

What do you think? Do you think something as simple as not providing a tray will prevent the behavior of getting more food than you need?

The post How Not to Get Fat: Facebook Cafeteria Prevents Overeating Through Poka Yoke appeared first on 6sigma.

There are numerous methods of preventing error or preventing defects. We discuss several of those in my series on Poka Yoke Examples. But, rarely, do we see an example of Poka Yoke where humiliation and embarassment was the primary method of preventing human error. Until now.

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The subway sign below shows a passenger getting caught by the automated doors. The sign is mean to warn passengers not to get caught between the closing doors. The sign says the following:

It’s painful to get caught between the closing doors. Even more [painful] are the eyes of those looking at you.

In other words, it’s physically painful to get caught between closing doors at the subway. But, even worse, are the other passengers pointing their fingers at you because you were stupid enough to get caught between the closing doors.

That’s the overall message. It’s both descriptive and witty. But, would it help you avoid making this mistake?

I think the concensus is that the sign is witty, catches your attention, but ultimately it probably won’t prevent people from making this mistake.

What is interesting is the message about embarrassment and humiliation.

What do you think?

The post Poka Yoke Example: Prevent Error Through Embarrassment and Humiliation appeared first on 6sigma.

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So, what does this article have to do with skateboarding? Read on.

I took my kids to a park last week and I noticed the park benches had these metal plates in the middle of them. At first look, I thought that was awkward. Then, I realized that those metal plates were there to prevent skateboarders from rail sliding across the park bench and ruining the edges of the bench. In other words, if a skateboarder tried to rail slide, his or her skateboard would end up getting destroyed – and, nobody wants their beloved skateboard ruined.

Are the metal plates more effective than a mere “No Skateboarding” sign? Yeah, I think so. This is a practical example of Poka-Yoke: it’s a method that prevents the defect from happening in the first place.

The post No Skateboarding Sign: A Poka Yoke Approach appeared first on 6sigma.

My family and I recently returned from a vacation. We went on a cruise – our first one. And, our experience was great. I highly recommend going on a cruise – much more affordable than Disneyland, that’s for sure.

There are other benefits too, but what I want to highlight today is an ingenious Poka-Yoke method for Toilets.

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Have you  ever been yelled at by your spouse or significant other for keeping the toilet lid up? Did you ever wish that there was a device that prevented you from making a mistake such as not placing the toilet lid down?

Well, the Poka-Yoke approach I found on the Carnival Cruise cabin eliminates that defect (it’ll prevent being yelled at).

Notice the toilet below in our cruise cabin. Do you see the toilet knob to flush?

In order to flush this toilet, you must place the toilet lid down because the flush handle is behind it. In other words, to flush, you have to place the toilet down.

This Poka-Yoke approach works and is incredibly simple.

The post Toilet Seat Down or Up? This Poka Yoke Forces You to Put Toilet Seat Down appeared first on 6sigma.

This specific experience I had highlighted the subtle but important fact around design and how to design in such a way that it helps the human. In other words, how to help the human prevent mistakes that he or she would likely make – because they are human.

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Conversely, there are designs that actually encourage mistakes. I believe this is one of those types of designs.

At an ATM recently, I found myself repeatedly hitting the “HELP” button. No, I didn’t mean to hit the “HELP” button – it was all accidental. Can you guess why from the image below?

That’s right, the “ENTER” button is right next to the “HELP” button.

As with most things, we bring our past experience into the situation and I’m accustomed to having the “ENTER” button on the far bottom right of the interface. So, my muscle memory immediately went to that location. But, on this interface, the button that occupies that location is the “HELP” button.

I made this mistake once, then twice. Then, I realized what was happening. But, my muscle memory immediately went to that location on the interface. Unfortunately, the interface encouraged me to make that mistake.

Redesign the ATM

Poka-Yoke, as we understand it, is a method to error proof or mistake proof our processes and devices. In fact, instead of catching the defect after it happens, Poka-Yoke is an approach that prevents the defect all-together.

One way to improve this interface is to move the “HELP” button away from the “ENTER” button. Having it close to the “ENTER” button can easily lead one to “fat finger” the “HELP” button unintentionally.

It’s Your Turn

What about you? What experiences do you have with everyday products and devices that could use some application of Poka-Yoke?

The post To Err is Human: ATM Machine Error Poka Yoke Design appeared first on 6sigma.

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Below is a table that describes the three common strategies for checking errors and I also describe the positive and negative or each approach.

Of course, the approach of Lean Manufacturing is to employ Poka-Yoke wherever possible, as it is the most low cost and low effort approach to achieving zero defects. But, as in some things, it depends on your operation.

The post How to Check for Errors appeared first on 6sigma.

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What is Dyslexia

Dyslexia is a broad term defining a learning disability. Common Dyslexia Symptoms include seeing letters as 3D figures, seeing letters upside down, backwards, or flipped characters. It can also affect short-term memory and vision.

If you think about it, there are many characters in the English language that are very easy to mistake. For example,

• V W: These are quite similar.
• i j: These are quite similar.
• m n     u: Sometimes, Dyslexics rotate the letters.
• b q p d: And, people with Dyslexia rotate the letters and they also exchange the letters.

Since the English alphabet makes it easy to make mistakes, a countermeasure to error-proof the English language by making slight improvements to the western script. In the context of lean, we call this approach Poka-Yoke.

Dyslexie Typeface: A Kaizen

Dyslexie Typeface was developed at the University of Twente by Christian Boer of Studiostudio. What they’ve done is simple but ingenious: they have exaggerated the differences between characters to make them easier to recognize. For example,

Make the underside of letters more bold:

Lengthen the ascender or descender of letters:

Emphasize the differences in the letters:

Make the openings in the letters exaggerated to make them easier to recognize:

What Christian Boer has done is nothing short of a Kaizen – he, with his team – literally improved an age-old standard and made it work for people with Dyslexia. By applying the principle of Poka-Yoke, he and his team developed a typeface that will allow people with Dyslexia to read better, comprehend better, and better manage Dyslexia.

credit: Christian Boer

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Poka-Yoke, or Error-Proofing or Mistake-Proofing, is an essential aspect of process improvement. In fact, Poka-Yoke is the method by which we can actually get closer to a goal of zero defects without an exponential increase in the cost to detect and eliminate defects. In this article, I’ll discuss two types of situations that would benefit from the approach of Poka-Yoke and provide general guidelines on how to develop robust process and systems with the help of mistake proofing.

In general, the approach of Poka-Yoke should follow the following guidelines:

1. Inexpensive
2. Based on common sense and obvious to the person involved in the process
3. It MUST eliminate Occurrence and Detection of the problem at the root cause

Occurrence Poka-Yoke

Occurrence is the situation as it happens, but sometimes after the fact. An example would be a buzzer or warning light. For example, a fire alarm is a type of Occurrence Poka-Yoke. In general Occurrence situation that merit Poka-Yoke can happen:

• There is a chance that the required action is not performed
• There is a chance that the required action is performed incorrectly
• There is a chance that information required to perform an action is not understood or misinterpreted
• There is a chance that complexity of process could lead to defects

For this situation, it’s important to follow these guidelines:

• At assembly, make sure that the wrong parts do not join together (think of Lego pieces that cannot join because they are not from the same Lego set).
• Use of 100% prevention devices such as contoured locators or fitted templates

Detection Poka-Yoke

In Detection, these situation should alert the operator at the point of mistake. For example, when one makes a mistake, an effective Poka-Yoke system will alert the operator that a mistake was made, where it was made, and even how the mistake was made.

Here are some techniques for detection oriented Poka-Yoke:

• Use color coded parts of graphics or images
• Before the fact, or before the defective part proceeds to the next step in the process, a Poka-Yoke system should alert the operator that 100% quality does not exist.
• It should be autonomous, or require almost zero intervention, but be an automatic response to a defect; almost reflexive.

The post Poka Yoke System Design: How To Mistake Proof Your Processes appeared first on 6sigma.

Practitioners of Lean Manufacturing and Six Sigma can use this tool to identify potential problems and their impact on a process. Before you continue reading, be warned: this post is long and is more of a “how to do fmea” than it is entertaining or fun. In that spirit, if you are learning how to apply an FMEA, then read on.

Problems and defects are expensive. Customers place high expectations on manufacturers and service providers to deliver quality and reliability.

Often, faults in products and services are detected through extensive testing and predictive modeling in the later stages of development. However, finding a problem at this point in the cycle can add significant cost and delays to schedules. The challenge is to design in quality and reliability at the beginning of the process and ensure that defects never arise in the first place. One way that Lean Six Sigma practitioners can achieve this is to use failure mode and effects analysis (FMEA), a tool for identifying potential problems and their impact.

FMEA: The Basics

FMEA is a qualitative and systematic tool, usually created within a spreadsheet, to help practitioners anticipate what might go wrong with a product or process. In addition to identifying how a product or process might fail and the effects of that failure, FMEA also helps find the possible causes of failures and the likelihood of failures being detected before occurrence.

Used across many industries, FMEA is one of the best ways of analyzing potential reliability problems early in the development cycle, making it easier for manufacturers to take quick action and mitigate failure. The ability to anticipate issues early allows practitioners to design out failures and design in reliable, safe and customer-pleasing features.

Now, let’s go into the details of the FMEA for itself and how to conduct an FMEA team exercise. In what follows, we’ll show an example, then watch the premium member-only video.

Finding Failure Modes

One of the first steps to take when completing an FMEA is to determine the participants. The right people with the right experience, such as process owners and designers, should be involved in order to catch potential failure modes. Practitioners also should consider inviting customers and suppliers to gather alternative viewpoints.

Once the participants are together, the brainstorming can begin. When completing an FMEA, it’s important to remember Murphy’s Law: Anything that can go wrong, will go wrong. Participants need to identify all the components, systems, processes and functions that could potentially fail to meet the required level of quality or reliability. The team should not only be able to describe the effects of the failure, but also the possible causes.

The sample shown in Figure 1 can be used as an example when learning how the FMEA works. The team in this case is analyzing the tire component of a car.

Figure 1: FMEA Template for Car Tire

Criteria for FMEA Analysis

An FMEA uses three criteria to assess a problem: 1) the severity of the effect on the customer, 2) how frequently the problem is likely to occur and 3) how easily the problem can be detected. Participants must set and agree on a ranking between 1 and 10 (1 = low, 10 = high) for the severity, occurrence and detection level for each of the failure modes. Although FMEA is a qualitative process, it is important to use data (if available) to qualify the decisions the team makes regarding these ratings. A further explanation of the ratings is shown in Table 1.

Table 1: Severity, Occurrence and Detection Ratings

After ranking the severity, occurrence and detection levels for each failure mode, the team will be able to calculate a risk priority number (RPN). The formula for the RPN is:

RPN = severity x occurrence x detection

In the FMEA in Figure 1, for example, a flat tire severely affects the customer driving the car (rating of 10), but has a low level of occurrence (2) and can be detected fairly easily (3). Therefore, the RPN for this failure mode is 10 x 2 x 3 = 60.

FMEA: Setting Priorities

Once all the failure modes have been assessed, the team should adjust the FMEA to list failures in descending RPN order. This highlights the areas where corrective actions can be focused. If resources are limited, practitioners must set priorities on the biggest problems first.

There is no definitive RPN threshold to decide which areas should receive the most attention; this depends on many factors, including industry standards, legal or safety requirements, and quality control. However, a starting point for prioritization is to apply the Pareto rule: typically, 80 percent of issues are caused by 20 percent of the potential problems. As a rule of thumb, teams can focus their attention initially on the failures with the top 20 percent of the highest RPN scores.

FMEA: Making Corrective Actions

When the priorities have been agreed upon, one of the team’s last steps is to generate appropriate corrective actions for reducing the occurrence of failure modes, or at least for improving their detection. The FMEA leader should assign responsibility for these actions and set target completion dates.

Once corrective actions have been completed, the team should meet again to reassess and re-score the severity, probability of occurrence and likelihood of detection for the top failure modes. This will enable them to determine the effectiveness of the corrective actions taken. These assessments may be helpful in case the team decides that it needs to enact new corrective actions.

The FMEA is a valuable tool that can be used to realize a number of benefits, including improved reliability of products and services, prevention of costly late design changes, and increased customer satisfaction.

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