Six Principles of Mistake Proofing

Some may say that it’s impossible to eliminate mistakes. And they are right; it is, most of the time. But, to be honest, they are missing the point.

Poka yoke, or mistake proofing, describes any behavior changing constraint that is built into a process to prevent an incorrect operation or act occurring.  The three aims of mistake proofing are:

• To reduce the risk of mistakes or errors arising.
• To minimize the effort required to perform activities.
• To detect errors prior to them impacting on people, materials, or equipment.

Ideally, poka-yoke ensures that proper conditions exist before actually executing a process step, preventing defects from occurring in the first place. Where this is not possible, poka-yoke performs a detective function, eliminating defects in the process as early as possible.

This can be achieved by following the 6 principles or methods of mistake proofing. These are listed in order of priority in fundamentally addressing mistakes:

1. Elimination seeks to eliminate an error-prone process step by redesigning the product or process so that the task or part is no longer necessary. This may require redesigning a new process or product simplification or part consolidation that avoids a part defect or assembly error in the first place.

Example:  An example of elimination is the use of ambient-light sensors to turn outside lighting on and off.

2. Prevention modifies the product or process so that it is impossible to make a mistake or that a mistake becomes a defect. This includes Limit switches to assure that a part is correctly placed or fixtured before process is performed; part features that only allow assembly the correct way, unique connectors to avoid misconnecting wire harnesses or cables, part symmetry that avoids incorrect insertion.

Example: An example would be a camera that will not function when there is not enough light to take a picture. Also some clothes dryers shut down when they detect an overheating situation.

3. Replacement substitutes a more reliable process to improve repeatability. This includes use of robotics or automation that prevents a manual assembly error.

Example: An example would be the implementation of an automatic dispenser to insure the correct amount of adhesive is applied during an assembly process or the coin dispenser in food stores preventing that customers are getting short changed.

4. Facilitation is the most used principle and employs techniques and combining steps to make a process step easier to perform or less error-prone. This includes visual controls including color coding, marking or labeling parts to facilitate correct assembly; checklists that list all tasks that need to be performed; exaggerated asymmetry to facilitate correct orientation of parts.

Example: An example would be to color code parts that are similar in shape. This would make it easier to identify the correct part for assembly. Another example would be the use of a slipping-type torque wrench to prevent over tightening. When gas stations introduced unleaded gasoline, the nozzle on the leaded pump was designed to be too big to fit into an unleaded tank, thereby preventing mistakes. Electrical outlets have been mistake proofed to assure proper polarity. It is impossible to put a plug in an outlet incorrectly.

5. Detection involves identifying a mistake before further processing occurs so that the operator can quickly correct the defect. This includes sensors in the production process to identify when parts are incorrectly assembled; scales to measure and control the weight of a package; built-in self-test capabilities in products.

Example: Examples would include a weld counter to ensure the correct number of welds or a software modification that will not allow incorrect entries. Also warning device, using sound and light, like the seat belt buzzers, can be used to predict when something is about to go wrong.

6. Mitigation seeks to minimize the effects or the mistake. This includes mechanisms that reduce the impact of a error and defect; products designed with low-cost, simple rework procedures when an error is discovered; extra design margin or redundancy in products to compensate for the effects of errors.

Example: An example would be a smoke or heat detector detecting a hazardous situation. Also fuses to prevent overloading circuits resulting from shorts are mitigation techniques.

Ideally, mistake-proofing should be considered during the development of a new product to maximize opportunities to mistake-proof through design of the product and the process (elimination, replacement, prevention and facilitation). Once the product is designed and the process is selected, mistake proofing opportunities are more limited (prevention, facilitation, detection and mitigation).

Eradicating human errors is crucial to any business. Errors cost money and impact customer satisfaction. By introducing simple measures to trap and stop errors organizations can not only save costs but also become more efficient. 

Sixteen Human Error Modes for Mistake Proofing

We all make mistakes, to err is human.  The question is why does it happen and how can you prevent it.  The essence of mistake-proofing is to design both products and processes so that human errors or mistakes are impossible to make or, at the least, they are easy and early to detect and correct. Poka-yoke is Japanese slang for mistake-proofing, a term coined by Shigeo Shingo.

When performing a mistake-proofing analysis on a manufacturing, service or business process, it is of course important to identify every human error possible during each process step. There are 16 human error modes particularly helpful to understand when identifying potential human errors.

The Sixteen Human Error Modes

1.     Omission

What part of the process is prone to be omitted?

2.     Excessive/Insufficient Repetition

What part of the process is prone to be excessively repeated?

3.     Wrong Order or Sequence

In what wrong sequence can the process be executed?

4.     Early/Late Execution

What execution can be early or late?

5.     Execution of Restricted Work

What tasks could be executed by unauthorized personnel?

6.     Incorrect Selection (or Identification)

What object of the process is prone to be incorrectly selected or identified?

7.     Incorrect Counting (or Calculating)

What objects of the process can be counted, measured, or calculated incorrectly?

8.     Misrecognition (or Misunderstanding or Misreading)

What misunderstanding or misreading is prone to occur?

What information, risk, or failure/error is prone to be overlooked?

What miscommunication is prone to occur?

What incorrect decision is prone to occur?

9.     Failing to Sense Danger

What information, risk, or failure/error is prone to be overlooked?

10.  Incorrect Holding

What object of the process are prone to mishandling?

11.  Incorrect Positioning

What positioning setting error is prone to occur?

12.  Incorrect Orientation

What orientation error is prone to occur?

13.  Incorrect Motion

What motion or movement error is prone to occur?

14.  Improper Holding

What object of the process are prone to mishandling?

15.  Inaccurate Motion

What motion or movement error is prone to occur?

16.  Insufficient Avoidance

What can be unintentionally touched, stuck, or splashed?

What movement can cause harm?

We must approach human error by considering the interfaces of the process that the operator is engaged in. The process should be designed to permit communication between the process and the operator.

Shingo argued that errors are inevitable in any manufacturing process, but that if appropriate Poka-yokes are implemented, then mistakes can be caught quickly and prevented from resulting in defects. By eliminating defects at the source, the cost of mistakes within a company is reduced.

Lean Quote: Lead by Example

On Fridays I will post a Lean related Quote. Throughout our lifetimes many people touch our lives and leave us with words of wisdom. These can both be a source of new learning and also a point to pause and reflect upon lessons we have learned. Within Lean active learning is an important aspect on this journey because without learning we can not improve.

"You don’t lead by pointing and telling people some place to go. You lead by going to that place and making a case." — Ken Kesey

Whether you realize it or not, if you're a leader, your employees are watching every move you make. Good leaders must lead by example. By walking your talk, you become a person others want to follow. When leaders say one thing, but do another, they erode trust--a critical element of productive leadership.

Leading by example sounds easy, but few leaders are consistent with this one. Successful leaders practice what they preach and are mindful of their actions. They know everyone is watching them and therefore are incredibly intuitive about detecting those who are observing their every move, waiting to detect a performance shortfall.

Leaders must lead with their actions as well as their words. Leaders can effectively translate intention into reality by acting on the concepts and messages they teach and the things they say to those around them. Leadership is the act of setting the right example for those who follow. Leadership is about actively demonstrating your belief, not just talking about it. People who say one thing but do another eventually lose credibility.

Leaders are not afraid to jump into the ‘trenches’ and do some of the work themselves. They also encourage team members to take risks and support them when they do. Being a hands on manager will inspire and motivate the team to achieve greater things.

When you “walk the talk,” your behavior becomes a catalyst for people’s trust and faith in you. And it also emphasizes what you stand for. Leading by example shows people exactly what you expect and gives them living proof that it can be done. On a deeper level, leading by example and being as good as your words builds trust. It’s a sign that you take what you say seriously so they can, too.

 

Lean PD App

Paul Akers has developed a new app that is a simple and elegant way to develop powerful daily habits. The Lean PD app (available in the App Store and Google Play) is the most effective way to develop yourself! Lean=efficient or elimination of waste. PD=personal development. So, Lean PD is the efficient way to personally develop yourself to reach your maximum potential. The whole concept is based on the idea of developing daily habits that support your BHAG (Big Hairy Audacious Goal). You will enjoy how simple and easy it is to transform your life by performing daily habits that support your goals.

Lean PD asks you to create a list of tasks you want to perform every day within a group of categories such as health, spirituality, exercise and leadership, among others. The App automatically logs tasks as incomplete, all you need to do is check the ones you completed and every night at midnight, the whole thing resets, so you start fresh every day. It is very elegant and simple, with very little management required. The Lean PD App allows you to view your daily, weekly, monthly and yearly progress so you get the big 40,000-foot-view. It graphically shows you how you’re performing in every category, so you know exactly where you need to improve.




The Lean PD App helps you be very deliberate about the things you eat and about the habits you’re developing on a daily basis.  If you’re pre-disposed to wanting to check things off and develop some healthy habits, the Lean PD App might be a great tool for you. It is simple, elegant and effective...everything we strive for when implementing Lean.
 

Reprise: The Seven Basic Quality Tools

Pascal Dennis recently said that the so-called ‘Seven QC Tools’ aren't second nature to everybody. I couldn't agree more with Pascal. In that spirit, I'll describe these core tools & how they can help.

The Seven Basic Tools of Quality is a designation given to a fixed set of graphical techniques identified as being most helpful in troubleshooting issues related to quality. They are called basic because they are suitable for people with little formal training in statistics and because they can be used to solve the vast majority of quality-related issues.

The tools are:

1. Check Sheets – A generic Tool which can be used for collection and analysis of data. A structured and prepared form that can be adapted for wide variety of issues
2. Control Charts – This is a graphical technique,which can be used to study the changes to a process over time
3. Pareto Chart – This is another graphical technique, which can be used to identify the significance of individual factors
4. Scatter Chart – This is used to identify the relation between variables, by plotting pairs of numerical data, with one variable on each axis. The points will be falling on a line or a curve, if the variables are related.
5. Cause and Effect Diagram (Also called as Ishikawa Diagram or Fishbone Diagram) – This can be used to structure the brain Storming Sessions. It is used to sort ideas into useful categories. Many Possible Causes are identified for a stated problem and the effect on the problem are identified
6. Flow Chart (Stratification Charts) - This tool is used to identify the patterns within the data collected from multiple sources and clubbed together. It is used to identify the meaning of the vast data by identifying patterns.
7. Histogram – It looks very much like a bar chart. it is used to identify the frequency of occurrence of a variable in a set of data.

The following presentation introduces the 7 basic quality tools:

The Seven Basic Tools of Quality from Tim McMahon
View more presentations from Tim McMahon.

Most organizations use quality tools for various purposes related to controlling and assuring quality. Although there are a good number of quality tools specific to certain domains, fields, and practices, some of the quality tools can be used across such domains. These quality tools are quite generic and can be applied to any condition.

The seven basic tools of quality can be used singularly or in tandem to investigate a process and identify areas for improvement, although they do not all necessarily need to be used. If a process is simple enough – or the solution obvious enough – any one may be all that is needed for improvement. They provide a means for doing so based on facts, not just personal knowledge, which of course can be tainted or inaccurate. Ishikawa advocated teaching these seven basic tools to every member of a company as a means to making quality endemic throughout the organization.

Lean Quote: We Cannot Have Thinking Without Facts

On Fridays I will post a Lean related Quote. Throughout our lifetimes many people touch our lives and leave us with words of wisdom. These can both be a source of new learning and also a point to pause and reflect upon lessons we have learned. Within Lean active learning is an important aspect on this journey because without learning we can not improve.

"We can have facts without thinking but we cannot have thinking without facts." — John Dewey

The general causes of troubles in factories arise from wrong knowledge and incorrect operations. To discern what is wrong and what is incorrect we have to launch into a fact finding process.

“The Facts.”

An overused expression.

Everybody assumes he knows, but no one actually knows.

One might be reminded of a story of the blind men touching an elephant and each reporting different description of what the elephant is.

One touches the trunk and talks only that, another touches the tail and describes the elephant as such.

Each believes his experience to be correct.

People often tell the stories from others as if they were their own experiences.

Discussions alone cannot eliminate troubles.

Words cannot always describe facts.

What is white may turn out as black.

Discussions cannot settle whether it is white or black.

“Let facts speak for themselves.”

With a humble attitude, carefully check things one by one.

At any rate what we are dealing with is a difficult thing.

It has an infinite number of features.

We must be aware that our knowledge and experience are finite, and always imperfect.

This recognition will make the facts appear.

A person who has engaged in a job for a long time is the one we call experienced.

As experienced person has a great deal of knowledge about that job.

These are correct knowledge and incorrect knowledge.

The problem is that he doesn’t know which is correct and which is wrong.

A true expert is the experienced person who is always furnishing his knowledge with facts, reflecting on that knowledge and making corrections.

Unfortunately, all persons with experience are not necessarily be true experts.

They can become encumbrances who bear superstitions.

We have to work diligently to find true knowledge.

It is just like in climbing a mountain road, you have to climb one step at a time.

After you’ve continued the climb for some time, you’ll suddenly realize how far you are above the starting point.

 

Lean Tips Edition #97 (Tip # 1456 - 1470)

For my Facebook fans you already know about this great feature. But for those of you that are not connected to A Lean Journey on Facebook or Twitter I post daily a feature I call Lean Tips.  It is meant to be advice, things I learned from experience, and some knowledge tidbits about Lean to help you along your journey.  Another great reason to like A Lean Journey on Facebook.

Click this link for A Lean Journey's Facebook Page Notes Feed.

Here is the next addition of tips from the Facebook page:

Lean Tip #1456 - Choose Courage Over Fear.

To be successful, you have to have courage. And to become courageous, do courageous things. Much of being successful is about going beyond what you think you're capable of -- venturing into the unknown. Whether you fail or succeed, you will learn and grow. Growth, in and of itself, means attaining a level of success whether it came from success or failure.

Lean Tip #1457 - Be Willing to Take Risks.

There are no guarantees on any path to success in life or business. The unknown is always looming. Therefore, risk and education are often the mechanisms necessary for knowing more clearly if you're on the right path.

If you're afraid to risk, you will put limits on your success and stay where you're comfortable. You cannot get what you want if you don't risk rejection and go for what you desire.

Lean Tip #1458 - Show Appreciation for Your Employees.

Workers who feel appreciated will be more motivated and productive. Praise employees publicly during meetings. Give spot awards. Profile employees and their work in company publications. If an employee puts in extra work on a project, recognize this. If you fail to reward hard work, your employees will not work as hard.

Lean Tip #1459 - Create a Culture of Accountability.

If workers are given ownership of their work and know they will receive feedback, they will work more meticulously. Accountability also means giving workers a clear sense of the direction of the company and how their work contributes to driving the company in that direction. If they feel like their work matters, rather than just being cogs in a huge machine, they will work harder.

Lean Tip #1460 - Invest in Training Your Employees.

All your employees will benefit from training, as it both makes them more valuable employees and creates a sense of indebtedness to the business, which leads to harder work. Pay particular attention to supervisors and middle managers who are just stepping into leadership roles. They are the key to transmitting upper management's vision and organizing work in an efficient manner, so extra management training for these positions will go a long way towards improving company productivity.

Lean Tip #1461 - Empower Your People

As you develop strong relationships you’ll see frontline employees wanting to step up. This is your opportunity to empower them. Encouraging authority, accountability, and responsibility at all levels creates a high performance team. Your role as leader is not to micromanage every detail of your organization but to rely on hundreds or thousands of people, each working toward a common purpose to be willing to make important decisions, exercise discretion, and answer for those choices. Let your employees know you trust them implicitly. They’ll earn it.

Lean Tip #1462 – Be Authentic, Share Yourself

One of the places most leaders fall down on the job is being inauthentic. They’re afraid to be vulnerable and known to others. Leadership has created a mental barrier that separates them from other people. Be honest about who you are, where you come from, and what you value. If you manage to practice all the previous strategies but don’t share your authentic self, you can’t build lasting relationships. Frontline leadership is about creating, reinforcing, and nurturing strong relationships.

Lean Tip #1463 – Expect Resistance to Change

Do not be surprised by resistance! Even if the solution a project presents is a wonderful improvement to a problem that has been plaguing employees, there will still be resistance to change. Comfort with the status quo is extraordinarily powerful. Fear of moving into an unknown future state creates anxiety and stress, even if the current state is painful. Project teams and change management teams should work to address resistance and mitigate it, but they should never be surprised by it.

Lean Tip #1464 – Seek Mentors.

Mentoring should be a necessity when it comes to planning out the improvement and development of future leaders. Mentoring is a popular idea for growth when it comes to leadership training. Make sure that your employees' mentor-mentee relationships don't just happen in a vacuum, however. One of the best benefits of mentoring is knowledge transfer, so give mentees and mentors structured ways to share what they've learned from these relationships. Successful employees have multiple mentors, so by building on that network effect, you allow leaders to branch and ultimately thrive.

Lean Tip #1465 - Lead With Passion, Not With Fear

Whether it be a good environment or a tumultuous one, leaders should never turn to invoking fear. In fact, in times of intense tension I believe that patience is even more important. Communication, clear objectives and performance feedback are critical in turbulent business environments but a fear-invoking boss can work to make bad situations worse. Lead your staff in an inspiring and passionate way – don't let their work be motivated by fear of your wrath. Remember intensity is different than fear. You can show passion but don't let it turn into intimidation.

Lean Tip #1466 - Have a Strong Lean Improvement Strategy

You'll need a solid plan and some attainable targets before implementing Lean. Utilize checklists and to-do lists, and you’ll always be working towards a goal. Look at every step in your process from the customer’s perspective: Is all that you’re doing something that he or she would be willing to pay for? If not, it is time to get back to the drawing board.

Lean Tip #1467 - Get the Whole Team on Board

To get the greatest advantages out of Lean, the entire organization should adopt and promote its practices, and extend its influence to suppliers as well. You must involve the people who are the closest to the work and you must get support from senior management as well.

In order to get people motivated, they must value the goals set for Lean manufacturing. These goals must be challenging, yet obtainable for your employees. Further, always ask for feedback on these goals, as well as progress toward target attainment. Feedback should always contain measureable facts and figures.

Lean Tip #1468 - Discard Conventional Fixed Ideas

Part of problem solving is thinking “outside of the box.” Encourage fresh perspectives and ingenuity in your team in order to develop innovative ways to forward Lean manufacturing without changing what is already efficient and successful. With such a rapidly evolving climate in manufacturing, sometimes conventional thought is what leads to the problem in the first place!

Lean Tip #1469 – Don’t Just Talk About it, Do it!

Once you have a Lean strategy in place, put it into fast and thorough action. Naturally, implementation is what ultimately yields results and improvement. The last think you want is to devise and formulate a Lean campaign that then sits on the shelf and collects dust. Run with your Lean plans as soon as you have everything nailed down.

Lean Tip #1470 - Concentrate on Bad Processes, Not People

By concentrating on the processes and building continuous improvement, you will have the culture change that you are looking for. Also, correct mistakes immediately. Don’t wait for the next shift, the weekend or maintenance to do it.