Poka-Yoke – Preventing Inadvertent Errors

By Al Norval (bio)

We talk a lot about the House of Lean with its foundation of Standards & Stability and the two pillars of Just In Time and Jidoka supporting a roof of Customer and Strategic Direction which together encompass engaged Team Members continually solving problems.

All of this makes sense but what is this Japanese word – Jidoka?

It’s built in quality at the source. Rather than try to inspect and test quality in by looking for defects on finished product, a losing cause at best, lean organizations build in quality at the actual value added operation. That way defects can be caught early and they don’t have to reply as heavily on final inspection testing.

The big advantage to Jidoka is that by catching defects early in the process, they are closer to the actual process conditions that caused the defect and therefore closer to root cause. They can launch problem solving faster with a higher chance of getting to root cause since the process conditions wouldn’t have changed as much.

Jidoka has four parts:

• Detecting defects
• Alerting or signaling a problem
• Immediate response - temporary countermeasures to get running again
• Root cause problem solving and countermeasures to prevent the occurrence of the defect.

This is where Poka-Yoke comes in. It’s about the final step in Jidoka of preventing the re-occurrence of the defect. Lean organizations realize that errors are inevitable. Human beings make errors that cause defects. By eliminating the possibility of the error being made, defects could be eliminated. Poka-Yoke is used to prevent these errors being made. Translated it means “Preventing inadvertent mistakes” since it’s believed people don’t make mistakes on purpose. This is consistent with the lean principle of “Respect for People”

The best Poka-Yoke devices are physical devices that eliminate the possibility of an error occurring. Weaker Poka-Yoke countermeasures would be signs and warning systems but these could be overridden and the error could still occur.

Organizations are always looking for ways to get employees involved and having teams develop Poka-Yoke devices that prevent errors from being made is a great way to do this. It’s a win-win. Employees are engaged in problem solving, quality gets better for customers.

For more on Poka-Yoke, download the free Lean Pathways “LEAN MANIFESTO”

Cheers

Al


In case you missed our last few blogs... please feel free to have another look…

Making the Invisible Visible in Design Projects
Two Pillars of the Lean Business System
Why Do We Learn More from What Did Not Work?
Failure is a Requirement for Innovation

The Four Levels of Visual Management, Part 2

By Pascal Dennis (bio)

Last time I talked about making problems visible through the four levels of visual management.

I described Levels 1 and 2, which have comparatively low power.

Today, our topic is visual management Levels 3 and 4 – the most powerful:

Level 3 – Organizes Behavior

Home positions for tools & equipment are a good example.

In a surgery, home positions provide a nice visual confirmation that sponges, scalpels and other equipment are back where they belong – and not inside the patient!

In manufacturing, having a home position for, say, our torque wrench and gauges, ensures a) they’re there when we need them, and, as important, b) we know when they’re not there.

“Right, Bonnie is doing her daily 2:00 pm torque audit.”

Other good examples include the ribbed perimeters, and studded lane lines of many highways. You know at once if you’re on the median or straddling your lane. You quickly correct your behavior.

Recently, I saw a nice kaizen in the Oncology department of a children’s hospital. Infections are a major risk in such wards. How to encourage staff & parents to decontaminate their hands before they enter the room?

Move the hand decontamination unit to the point of entry. You can’t enter without seeing and using it, and compliance rates have spiked.

Level 4 – The Defect is Impossible

Lean thinkers will recognize the ‘pokayoke’ concept. We develop such a deep grasp of our process and its possible failure modes, that we install gizmos and practices that make them impossible!

Manufacturing is full of these: alarms on torque wrenches, electronic lights and safety mats that disable the machine if a team member enters the line of fire, gasoline nozzles that won’t fit diesel tanks and so on.

In Health Care, pokayokes on gas lines make it impossible to mis-connect oxygen and other gas lines.

As we get better at Lean, our visual management naturally progresses from Level 1 to Level 4.

Once we’re good at Level 1 and 2 visual management, we begin to think. “The same defect – here we go again! How do we prevent it?”

Who is the best source of Level 3 and 4 visual management?

Why, our front line team members, of course.

That’s why total involvement is critical. Alienate the front line and you lose all their insight & creativity. Problems mushroom!

But you already know that…

Best regards,

Pascal

The Four Levels of Visual Management, Part 2

By Pascal Dennis

Last time I talked about making problems visible through the four levels of visual management.

I described Levels 1 and 2, which have comparatively low power.

Today, our topic is visual management Levels 3 and 4 – the most powerful:

Level 3 – Organizes Behavior

Home positions for tools & equipment are a good example.

In a surgery, home positions provide a nice visual confirmation that sponges, scalpels and other equipment are back where they belong – and not inside the patient!

In manufacturing, having a home position for, say, our torque wrench and gauges, ensures a) they’re there when we need them, and, as important, b) we know when they’re not there.

“Right, Bonnie is doing her daily 2:00 pm torque audit.”

Other good examples include the ribbed perimeters, and studded lane lines of many highways. You know at once if you’re on the median or straddling your lane. You quickly correct your behavior.

Recently, I saw a nice kaizen in the Oncology department of a children’s hospital. Infections are a major risk in such wards. How to encourage staff & parents to decontaminate their hands before they enter the room?

Move the hand decontamination unit to the point of entry. You can’t enter without seeing and using it, and compliance rates have spiked.

Level 4 – The Defect is Impossible

Lean thinkers will recognize the ‘pokayoke’ concept. We develop such a deep grasp of our process and its possible failure modes, that we install gizmos and practices that make them impossible!

Manufacturing is full of these: alarms on torque wrenches, electronic lights and safety mats that disable the machine if a team member enters the line of fire, gasoline nozzles that won’t fit diesel tanks and so on.

In Health Care, pokayokes on gas lines make it impossible to mis-connect oxygen and other gas lines.

As we get better at Lean, our visual management naturally progresses from Level 1 to Level 4.

Once we’re good at Level 1 and 2 visual management, we begin to think. “The same defect – here we go again! How do we prevent it?”

Who is the best source of Level 3 and 4 visual management?

Why, our front line team members, of course.

That’s why total involvement is critical. Alienate the front line and you lose all their insight & creativity. Problems mushroom!

But you already know that…

Best regards,

Pascal

Pascal Dennis Bio

Poka Yoke & Respect for People

By Al Norval

I’ve heard Poka Yoke described as “Mistake Proof and Fail Safe” but as with most things in Lean it actually goes much deeper than that. The best translation of Poka Yoke that I’ve come across says that it means “To prevent inadvertent mistakes”. I really like this definition since it ties in several fundamental Lean principles.

The first is quality at the source. We do this by preventing the errors that lead to defects. Errors that are made when the work is being done. To err is human and to expect humans not to make errors is unrealistic. Recognizing this we need to look for ways to prevent the errors from being made. We do this through the use of physical devices that make it impossible to make the error. The best Poka Yoke devises are simple, reliable and designed by the teams themselves. Where we can’t use physical devices we resort to using visual aids such as signage, markings, alarms and check-sheets. By their very nature, these are not nearly as effective at preventing errors from being made.

Have you ever seen someone driving their car with the dashboard engine light on?

How about someone running a red light at an intersection?

Both errors can lead to very expensive defects.

The second Lean principle involved is “Respect for People”. By recognizing the purpose is to prevent “Inadvertent mistakes” a much greater respect is shown to people than to call it “Idiot Proofing” which is a common name I’m sure we have all heard of. We all make mistakes and we all make errors. Sometimes these lead to defects and sometimes they don’t. Have you ever had a close call and thought to yourself “Phew – I got away with one this time”?

Isn’t a better way – to surface the near miss and use the capabilities of the team to come up with ways of preventing the mistake/error from being made? I think so and I believe you’ll find it very empowering for the team. After a little practice, you’ll be amazed at what they come up with.

Cheers

Poke Yoke – Preventing Inadvertent Errors

By Al Norval

We talk a lot about the House of Lean with its foundation of Standards & Stability and the two pillars of Just In Time and Jidoka supporting a roof of Customer and Strategic Direction which together encompass engaged Team Members continually solving problems.

All of this makes sense but what is this Japanese word – Jidoka?

It’s built in quality at the source. Rather than try to inspect and test quality in by looking for defects on finished product, a losing cause at best, lean organizations build in quality at the actual value added operation. That way defects can be caught early and they don’t have to reply as heavily on final inspection testing.

The big advantage to Jidoka is that by catching defects early in the process, they are closer to the actual process conditions that caused the defect and therefore closer to root cause. They can launch problem solving faster with a higher chance of getting to root cause since the process conditions wouldn’t have changed as much.

Jidoka has four parts:

• Detecting defects
• Alerting or signaling a problem
• Immediate response - temporary countermeasures to get running again
• Root cause problem solving and countermeasures to prevent the occurrence of the defect.

This is where Poka Yoke comes in. It’s about the final step in Jidoka of preventing the re-occurrence of the defect. Lean organizations realize that errors are inevitable. Human beings make errors that cause defects. By eliminating the possibility of the error being made, defects could be eliminated. Poka Yoke is used to prevent these errors being made. Translated it means “Preventing inadvertent mistakes” since it’s believed people don’t make mistakes on purpose. This is consistent with the lean principle of “Respect for People”

The best Poka Yoke devices are physical devices that eliminate the possibility of an error occurring. Weaker Poka Yoke countermeasures would be signs and warning systems but these could be overridden and the error could still occur.

Organizations are always looking for ways to get employees involved and having teams develop Poka Yoke devices that prevent errors from being made is a great way to do this. It’s a win-win. Employees are engaged in problem solving, quality gets better for customers.

For more on Poke Yoke, see The Lean Pathways “LEAN MANIFESTO”

Cheers

The Value of Images

By Al Norval

What is the value of an image?

We’ve all heard the old adage – “A picture is worth a thousand words” but what is the real value that’s implied by this phrase? We all know that value is driven by the customer so what value do customers see in images?

Let’s start at the beginning - who is the customer of the image? It’s the person who is receiving the information the image is conveying.

What do the customers want? To receive the information in the least waste way; this means understanding it at a glance and to be able to retain the information.


Let’s look at an example situation. We have new hires into the organization and are trying to bring them up to speed quickly and safely without compromising quality. They are the customers of our training process. We use a TWI based process where we have an experienced trainer and standardized work.

Would our customers, the trainees, see value in images so they can tie what their instructor has shown them to the critical elements of the work? Of course! Images reduce training time and take away much of the confusions that occur when using only words even when we show people as well as talk them through the steps.

Would our customers, the trainees, see value in being able to use images to poke yoke their standard work after the training? Again the answer is Yes. Simple images trigger recall of key learning points.

What is it that makes images so powerful in learning a new concept? Images are much deeper, richer and convey more information. Our brain reacts differently to images. Images cause an emotional connection to be formed in our brains so we form more neural connections with images than with words only. This means we have a greater rate of retention with images and a faster recall of the learning point.

My observation from working with many different organizations is that most training consists of slide after slide of PowerPoint? Why? Because it fits into computer systems better. In reality, our minds work so much faster than the words appear on the screen that we become bored and don’t retain the key teaching points. I believe that images are undervalued in training and we in the Lean community should be striving to change this as part of our work.

For more information on the use of Lean images in training, see Lean Pathways Images.