A presentation on the Introduction, Purpose, History & Origin, Concept, Principles, Methods, Types & Implementation of Poka-Yoke [Mistake Proofing] in any manufacturing or service setting.

1. By
PRANEET SURTI
POKA - YOKE
ポカ-ヨケ
Fail-Safing I Mistake Proofing I Idiot Proofing
1

2. The Best approach is to dig out and
Eliminate Problems where they are
assumed not to Exist
“
“
- Shigeo Shingo 2

3. History & Origin
CONTENTS
03
Steps towards Implementation
General idea of Poka-Yoke &
Its underlying Principles,
Types & Methods
Generic & Technical
Examples of Poka Yoke
INTRODUCTION IMPLEMENTATION
CONCEPT & PRINCIPLE EXAMPLES
02 04
01
3

4. INTRODUCTION
Lean Management has adopted the principles and techniques originating as part of the Lean
Manufacturing methodology and developed them further. Now we can experience Lean's benefits in
management and transfer successful techniques from the times of post-war Japan to modern-day
business conditions.
One of the most valuable takeaways is Poka-Yoke. It has become one of the most powerful work
standardization techniques and can be applied to any manufacturing or service industry.
The term Poka-Yoke (poh-kah yoh-keh) was coined in Japan during the 1960s by Shigeo Shingo, an
industrial engineer at Toyota. Shingo also created and formalized Zero Quality Control – a combination
of Poka-Yoke techniques to correct possible defects and source inspection to prevent defects.
Poka-Yoke are mechanisms used to eliminate errors by effectively making it impossible to make
mistakes in a given process.
4

5. INTRODUCTION
Actually, the initial term was baka-yoke, meaning ‘fool-proofing’/ ‘Idiot Proof’, But this put the focus on
the person, not the operation. It also caused one employee to burst into tears and declare “I am not
an idiot!”, according to an article in the Harvard Business Review (HBR) titled, “Poka-Yoke is Not a Joke.”
Thus, Shingo changed the name from the harsher “idiot-proof” to the milder “mistake-proof,” because his
goal for poka-yoke was for it to help eliminate mistakes as simply and cost-effectively as possible.
Poka-Yoke means ‘mistake-proofing’ or more literally – avoiding (yokeru) inadvertent errors (poka).
Poka-Yoke ensures that the right conditions exist before a process step is executed, and thus
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. Its idea to prevent errors and
defects from appearing in the first place is universally applicable and has proven to be a true efficiency
booster.
Poka-Yoke is any mechanism in a Lean manufacturing process that helps to avoid mistakes.
5

6. INTRODUCTION - PURPOSE
The purpose of the poka-yoke technique is to eliminate product defects by
● Preventing them in the first place,
● Correcting them or
● Drawing attention to human errors as they occur
Poka-yoke was developed as a key component of the Toyota Production System (TPS), but the
tool can prove useful in any industry.
It is a foundational tool of both Lean, which targets Waste, & Six Sigma, which focuses on Defects,
with a goal of eliminating every mistake by creating systems that either immediately prevent or
detect them. Poke-yoke reduces the waste caused by defects, which can help improve efficiency
and save costs in rework or additional processing.
Poka-yoke is an ongoing process. One of the key factors that too often is ignored in continuous
process improvement is the “continuous” part. Poka-yoke provides for that, creating solutions for
mistakes that take care of the issue going forward, not for just one instance.
6

7. HISTORY &
ORIGIN
The ideas that became Poka-Yoke were introduced by Shigeo Shingo, an industrial engineer who was a
Consultant to Toyota and a significant contributor in the Lean Practices that makes TPS
In 1961, Shingo visited a plant where a very simple assembly procedure was resulting in Defective Parts being
sent to the parent company. The cause of the Problem was that employees were forgetting to put springs
into an On/Off switch. The parent company tried to resolve the issue by sending an Inspector, but it was
Time-Consuming and Expensive.
Shingo realized Two Truths:
● Sometimes we Forget things
● Sometimes we also Forget that we have
Forgotten Something.
Having reached the root cause of the problem, Shingo started to design
ways to error-proof operations and help people remember their job
requirements. This included creating checklists for each day on the job.
7

8. ORIGIN
Though Shigeo Shingo is the First Name that strikes when we talk about Poka Yoke,
Well, the concept of Poka Yoke has been used from ages.
In Fact, the concept of Jidoka [Autonomation] that lays a foundation
for Poka Yoke was introduced in 1900s by Sakichi Toyoda, Years before it
was Published in 1960s by Shingo.
Evolution of Jidoka
8

9. HOW IMPORTANT is POKA-YOKE?
It’s still a key part of the Toyota Production System, as a feature of the
Jidoka system, one of the two pillars of the TPS. Jidoka identifies the
causes of problems and allows for the stopping of a process
by man or machine rather than producing something
defective.
The value of using Poka-Yoke is that they help people and processes
work right the first time, which makes mistakes impossible to
happen.
Poka Yoke significantly improve the quality and reliability of products
and processes by eliminating defects.
This approach to production fits perfectly the culture of continuous
improvement, which is also part of the Lean management arsenal.
It can also be used to fine tune improvements, and process designs
from six-sigma Define – Measure – Analyze – Improve – Control
(DMAIC) projects. 9

10. TESLA MODEL 3
Self-driving cars are slowly becoming a fairly common sight on the roads. Tesla recently showed a video
of its Model 3 backing out of a parking space and slowly maneuvering its way to pick up its owner, who
had called it via his smartphone. In another more terrifying instance, a Model 3 driver from Florida
experienced seemingly inexplicable braking from the Tesla's autopilot feature while traveling at
highway speeds, only to find out a split second later that the car in front of them swerved out of the
lane to reveal a stopped car. Tesla's sensor had automatically detected the hazard and acted (without
human input) to avoid a crash.
Self-driving cars are a modern consumer-based example of poka-yoke. They operate by using multiple
sensors and alerts like automatic braking and a variety of cameras to
"see" everything around them in real time. In fact, automatic
braking systems are becoming a common feature
in most new cars, helping prevent accidents
due to human error.
10

11. WHEN TO USE ?
● When a process step has been identified where Human Error can cause Mistakes or
Defects to occur, especially that rely on the Worker’s Attention, Skill, or Experience
● In a service process, where the Customer can make an Error which affects Output
● At a Hand-Off Step [HOTO] in a process, when output (or for service processes, the
customer) is transferred to Another Worker
● When a Minor Error Early in the process causes Major Problems Later in the process
● When the Consequences of an Error are Expensive or Dangerous
● Poka Yoke can be used in Designing a New Process & also Improving an Existing Process.
11

12. TYPES OF ERROR: GENERAL MANUFACTURING
● Processing Error: Process operation missed or not performed per the standard
operating procedure.
● Setup Error: Using the wrong tooling or setting machine adjustments incorrectly.
● Missing part: Not all parts are included in the assembly, welding, or other processes.
● Improper Part/Item: Wrong part used in the process.
● Operations Error: Carrying out an operation incorrectly; having the incorrect version of
the specification.
● Measurement Error: Errors in machine adjustment, test measurement, or dimensions
of a part coming in from a supplier.
● Last Slide MEntioned Errors a couple of times, Let’s have a look on a few generic Manufacturing Errors
12

13. RELATIONSHIP MATRIX: ERRORS & CAUSES
13

14. HOW SHOULD I START ?
● OEE
● VOC, VOB & CTQs
● Flow Chart/ FMEA/ HIRA
● Value Stream Mapping
● Customer Complaints
● Control Charts
● Pp, PpK & Cp, Cpk
● Process Deviations
● OTIF Data
● Safety associated Retained Documented Information
●
Seek for Defects, Delays, Accidents, Waste & Mistakes in your existing Process.
Tools/ Documented Information/ Data that can help you fetch the details for Picking a right Poka Yoke includes:
These will help us to Identify
Processes where Poka-Yoke can
be Implemented effectively
14

15. WHERE
● Ideally, poka-yoke devices ensure a process is designed so mistakes are prevented
before they happen.
● When this is not possible, poka-yoke takes on more of a detective role, eliminating
defects in the process as early as possible.
● A prevention-based poka-yoke system acts before the defect happens; devices sense an
abnormality is about to happen and issue an alert.
● A detection-based poka-yoke system immediately signals an operator as soon as a
mistake is made. It then does not allow the process to continue, enabling the operator to
quickly fix the error.
● 15

16. WHERE
● The best location for a poka-yoke device is before an operator or the machine starts a
task. In other words, it's best to prevent any errors by not allowing the process to even
begin until a certain set of conditions are met.
● The second-best location for a poka-yoke device is during a particular step within a
process. This way, an operator or machine receives an alert in the event of an error and stops
the part or process from moving down the line.
● Finally, the third-best location for a poka-yoke device is downstream after the process
step is finished, typically at an inspection station. At this point, you're assuming errors or
defects may have occurred and are dependent on detection controls to find the defects before
sending the process down the line.
Once you've decided on which process could benefit from a poka-yoke , there are a few areas to consider placing the device
or method within the workflow. The location of the device within the process workflow can affect its level of effectiveness.
16

17. POKA YOKE - APPROACHES
WARNING
This approach senses a problem and stops a line or
process so that corrective action can take place
immediately, thus avoiding serial defect generation.
CONTROL
02
01
This approach signals the occurrence of a deviation or
trend of deviations through an escalating series of buzzers,
lights or other warning devices. However, unlike the control
method, the warning method does not shut down the
process on every occurrence.
17

18. APPROACHES
WARNING APPROACH
Poka-yoke devices take on one of two approaches: the control approach and the warning
approach.
Devices using the control approach
sense a problem and stop the process,
so actions can be taken to correct the
issue immediately.
CONTROL APPROACH
Devices using the warning approach
detect and alert to the occurrence of a
deviation (or trend of deviations)
through an escalating series of warning
devices (buzzers, lights, etc.)
The difference between warning approach and the control approach is that the warning
approach does not shut down the process every time an error is detected.
18

19. POKA-YOKE PRINCIPLES
19

20. PRINCIPLES
1. Elimination “Don’t do it Anymore” is to eliminate the possibility of error by redesigning the
product or process so that the task or part is no longer necessary.
2. Prevention “Make sure it can never be done Wrong” is to design and engineer the
product or process so that it is impossible to make a mistake at all.
3. Replacement “Use something Better” is to substitute a more reliable process to improve
consistency.
4. Facilitation “Make tasks easier to Perform” is to employ techniques and to combine
steps to make work easier to perform.
5. Detection “Notice what is going Wrong and Stop it” is to identify an error before further
processing occurs so that the user can quickly correct the problem.
6. Mitigation “Don’t let the situation Get too Bad” is to seek to minimize the effects of
errors.
Poka Yoke is based on 6 principles. Listed in order of preference in fundamentally addressing mistakes:
20

21. PRINCIPLES
21

22. PRINCIPLES
22

23. IMPLEMENTING POKA YOKE
CREATE
PROCESS FLOW
MAKING IT IMPOSSIBLE FOR
ERROR TO OCCUR
FIND SOURCE FOR EACH
POTENTIAL ERROR
RESULTS
DETECT THE ERROR AND MINIMIZE ITS EFFECTS
01 02
03
04
05
23

24. MISTAKE PROOFING PROCEDURE
1. Obtain or create a flowchart of the process. Review each step, thinking about where and when human
errors are likely to occur.
2. For each potential error, work back through the process to find its source.
3. For each error, think of potential ways to make it impossible for the error to occur. Consider:
a. Elimination: eliminating the step that causes the error.
b. Prevention: Make sure it can never be done Wrong
c. Replacement: replacing the step with an error-proof one.
d. Facilitation: making the correct action far easier than the error.
4. If you cannot make it impossible for the error to occur, think of ways to detect the error and
minimize its effects. Consider inspection methods by Setting up Detection & Mitigation
5. Choose the best mistake-proofing method or device for each error. Test it, then implement it. Three
kinds of inspection methods provide rapid feedback:
a. Successive inspection is done at the next step of the process by the next worker.
b. Self-inspection means workers check their own work immediately after doing it.
c. Source inspection checks, before the process step takes place, that conditions are correct. Often it’s
automatic and keeps the process from proceeding until conditions are right.
24

25. WHY POKA YOKE ?
POKA YOKE APPLICATION AREA
● The Reason I this Technique !
25

26. TYPES OF POKA YOKE
CONTACT METHOD
a.k.a PHYSICAL
CONTACT METHOD
a.k.a MOTION STEP
METHOD
a.k.a FIXED VALUE
METHOD
SEQUENCE METHOD
CONSTANT NUMBER
METHOD
01 02 03
There are three recognized types of poka-yoke that, when implemented, can greatly reduce human errors by
effectively making it impossible to make a mistake in a given process.
26

27. 01 CONTACT METHOD a.k.a PHYSICAL CONTACT METHOD
The contact method of poka-yoke uses some type of sensing device to
identify defects in a part's shape, size, color or other physical
attribute. Things like notches with matching locator pins, interference
pins, limit switches and proximity switches are used to make certain a part
is positioned correctly before work begins.
Contact methods are good in any circumstances that encourage
mistakes. These are situations that involve rapid repetition, infrequent
production or issues with surrounding environment like poor lighting,
extreme temperature, excess humidity, noise, dust or any other factor that
may distract an operator.
27

28. 02 CONSTANT NUMBER METHOD a.k.a FIXED VALUE METHOD
The constant number (fixed-value) method of poka-yoke is used in
processes where the same action is repeated several times. In other
words, the fixed-value method alerts operators once a certain number
of movements has been made.
A great example of this method is giving an operator a bin containing the
exact number of parts needed to complete a task. If there is a part left
over, the product would be considered defective and not allowed to move
to the next stage. So, if the operator needed to install six bolts, the bin
would only contain six bolts.
28

29. 03 SEQUENCE METHOD a.k.a MOTION STEP METHOD
The sequence (motion-step) method of poka-yoke is employed when a
process requires several different activities be completed in
sequence by the same operator. The poka-yoke device for this method is
created to detect whether each motion is performed and to alert the
operator when a step is skipped. A good example of a sequence
poka-yoke device is utilizing a simple proximity switch that opens only
after all components are loaded in the correct order. Likewise, the device
can detect when each component is used (or removed) from its dispenser.
If one component is not removed, an alert is sent to let the operator know
not to proceed.
29

30. HOW
There are a few things to consider when initially employing the poka-yoke techniques and methodology.
Before anything can happen, management must be willing to devote resources and support for
implementing not only the poka-yoke procedures but the devices as well. Next, you'll need to provide
adequate training to operators on the new process(es) and equip them with the tools and skills
necessary to do their job.
1. Build the team
2. Select the process
3. Map the process
4. Identify risk
5. Find the source
6. Outline your options
7. Choose the method
8. Implementation and validation
30

31. HOW
1. Build the team: The first step in implementing poka-yoke is building a cross-functional team to review
current processes. Your team should include operators, quality technicians, manufacturing and quality
engineers, and production supervisors. Each team member should be trained on poka-yoke methodologies
and have a working knowledge of the processes in question. It's also a good idea for them to know about any
process error or product defect history.
2. Select the process: Choose a process you want to evaluate. The selection could be based on the overall
impact it has on the company's key performance indicators (KPIs), the complexity of the process, frequency of
errors, warranty history or its quality-control history. Try to select a process that has a significant chance for
improvement.
3. Map the process: With your team, review each step in the process flow chart, looking for any areas where
defects have occurred in the past or have a high potential to occur. If you don't have a process flow chart,
create one.
31

32. HOW
4. Identify risk: With your team, brainstorm all the possible errors that could occur within the process in
question, keeping in mind when human errors are likely to happen. Failure mode and effects analysis (FMEA) &
Quality Matrix (QM) is a great tool for identifying risk.
5. Find the source: Start with each potential error and work your way back through the process flow to figure
out the point of initiation. Brainstorm ways to prevent the error by examining the point of initiation.
6. Outline your options: Now that you've identified potential errors, brainstorm ways to make it impossible
for those errors to occur. Options should include simplifying the step so the action is simpler to perform than
the error, eliminating the step by asking if it is necessary and adds value, and implementing poka-yoke to
make it impossible to create an error during the step.
7. Choose the method: If you decide to implement poka-yoke, meaning the step can't be simplified or
eliminated, it's time to choose the best poka-yoke method for the process. This means collectively deciding on
the contact, fixed-value or motion-step method of poka-yoke. 32

33. HOW
8. Implementation and validation: Develop and/or select the poka-yoke device or method and implement it
into the existing process, ensuring operators are aware of the changes being made and how they will be
affected. Over time, measure the effectiveness of the change(s) by monitoring efficiency, error reduction,
rework and scrap..
33

34. BENEFITS
● Operators will need less training because processes containing poka-yoke devices
automatically correct any deviation from what is required.
● An increase in safety is an added benefit where workers are exposed to hazardous materials or
dangerous machinery such as when working with high-inertia machines or petrochemicals.
● Fewer quality checks through sampling and inspection are needed thanks to the
mistake-proofing aspects of poka-yoke. While inspections still have their place, with poka-yoke,
eliminating mistakes is built into processes through the prediction or detection of errors or
defects.
● Work becomes less repetitive for operators, as it helps them work through processes
error-free the first time, which prevents them from having to go back and do it again correctly.
● The quality of processes is improved, resulting in higher quality products. Improved
processes also begin to produce effective teams that work in a coordinated effort to deliver
error-free products the first time.
Aside from the obvious goals of eliminating human and mechanical errors and not accepting, allowing or passing along
defects within a manufacturing setting, poka-yoke can yield other benefits that are not quite as evident.
34

35. BENEFITS
35

36. SUMMARY
● Poka-Yoke technique is one of the most precious gems in the crown of Lean management.
● It is a way of ensuring quality without actually having a quality assurance process, rather than
preventing defects to appear in the first place.
● Poka-Yoke may be implemented in any industry and have many benefits, the most important of
which are:
- Helps work right the first time
- In time makes it impossible for mistakes to occur
- It’s not costly
36

37. SUMMARY: POKA-YOKE AT A GLANCE
What: Mistake Proofing Technique
Why: Avoid Human Errors
When: Designing a New Process & also Improving an Existing Process
Where: Before Task, Between Task & After Task
Who: Shigeo Shingo, 1960s
Principles: Elimination, Prevention, Replace, Facilitate, Detection & Mitigation
Approaches: Control & Warning
Types/ Methods: Contact Method, Constant Number & Sequence Method
Inspection Methods: Successive inspection , Self-inspection & Source inspection checks
37

38. EXAMPLES : GENERAL EVERYDAY LIFE
1. Microwave oven does not work until the door is shut.
2. Washing machines only start when door is closed & cannot be opened until the cycle is over
3. Electric plugs have an earth pin that is longer than the other pins and is the first to make
contact with the socket. The protective shield of the neutral and earth sockets are then
opened safely.
4. Electric sockets are shaped in a manner that only one way of plugging-in is possible. This
prevents the possibility of a short-circuit occurring.
5. Elevator doors have a sensor that causes them to open when there is an obstruction-this
prevents injury to someone trying to enter as the doors are closing.
6. Box cutters have a retractable blade that only pops out when the handle is held.
7. Lawn mowers have a safety bar on the handle that when released, switches off the machine.
8. Circuit breakers in the home electrical system prevent electrical overloads.
9. Overflow outlets in bathroom and kitchen sinks prevent flooding of the house when the
drain is blocked
Many people lose their lives or get maimed through vehicular accidents each year. Safety of users of automobiles
is of paramount importance and many measures have been taken to make them safe.
38

39. EXAMPLES : IN AUTOMOBILES
1. Cross-traffic alerts warn drivers of impending traffic when they are reversing from a
parking position. this device is more of a warning and must be used in-conjunction with
other devices to be successful.
2. Adaptive headlights are able to respond to the conditions on the road so as to assist the
driver have better visibility. For example, they are able to illuminate curved roads and also
during bad weather.
3. Airbags deflate quickly after an accident to prevent injury to the occupants of the vehicle.
4. Seat belt pre-tensioners assist in holding the passenger in place in case of an accident and
prevent them from sliding through
5. Blind spot assist warns the driver when there are objects within the blind-spot range that
are not visible
6. EBS braking distributes power evenly and the discs expand symmetrically when hot. This
minimises uneven tear of the discs
Many people lose their lives or get maimed through vehicular accidents each year. Safety of users of automobiles
is of paramount importance and many measures have been taken to make them safe.
39

40. EXAMPLES : GENERAL EVERYDAY LIFE
1. Magnets in a grain packaging plant detect and remove metal pieces before they are packed.
2. Interlock switches which detect the position of a machine guard and switch off the machine
when the guard is lifted. The machine will never operate when the guard has been lifted and
this prevents accidents to the operator.
3. Light curtains in a factory detect when someone is near very dangerous machines and
switches off the machine to prevent injuries.
4. Power guards on high inertia machines with moving parts prevent opening until the parts
have stopped completely in order to prevent accidents.
5. Machines that must be controlled using both hands ensure that some distance is kept
between the operator and dangerous machine parts.
6. In the food industry, gloves and other small pieces of personal protective equipment
must be blue in colour for ease of detection in case they fall into food. This is because
blue foods are rare in nature and the color difference makes it easy to detect.
In lean manufacturing systems, poka yoke also includes a philosophy of constantly working to prevent mistakes
from occurring in the first place.
40

41. EXAMPLES : GENERAL EVERYDAY LIFE
7. Using standardized containers at the workstation enables workers to know exact
quantities without having to weigh or count the contents.
8. Use of colour coded date labels to mark the production dates of products. This way the
different batches are easily identifiable for the purpose of product rotation.
In lean manufacturing systems, poka yoke also includes a philosophy of constantly working to prevent mistakes
from occurring in the first place.
41

42. EXAMPLES : PRODUCTS
1. Glow-in-the-dark strips around the toilet bowl prevent users from urinating on the sides.
2. Mop slippers save time for the busy person as they prepare to go to work or school.
3. Scrap collecting bowl has a ledge that is attached to the table top to collect vegetable scraps
before they fall on the ground.
4. Oven rack guard prevents accidental burns as one is removing food from the oven chamber
5. Locator stickers that are put on commonly lost items such as keys and can be traced using the
phone.
6. Upside-down tomato sauce bottles enable the consumer to use up all the tomato sauce and
also lets the water that collects at the bottom come out first.
7. Mobile phones are designed in such a way that when they fall, the cover separates so as
to minimise the shock that would damage them.
8. Color-coding of electrical wires is meant to prevent short circuiting that can occur if they are
not matched properly.
9. C-Type Charger to avoid damage in the Female Socket in the Phone.
Safety concerns necessitate the use of mistake proofing techniques on the final product in order to prevent harm
to the final consumer. It also provides ease of use to the product so as to enable the final consumers to be able to
solve their problems effectively.
42

43. EXAMPLES : NATURE
1. Coughing is a natural reaction that prevents the error of foreign bodies from entering into the
lungs. The sensitive wall linings of the respiratory tract detect and eject minute particles throug
coughing.
2. Veins have valves that are designed to prevent the error of back-flow of blood as it travels
through the system. They also allow some blood to collect within the system without busting a
they have a larger internal diameter.
3. Arteries have thick walls that can withstand the high pressure that blood from the heart
exerts on the circulatory system.
4. Tearing is a necessary reaction to the entry of foreign bodies into the eye.
5. Mucus membrane traps bacteria and prevents the error of pathogens entering the system.
6. The skin is the first defence against entry of foreign bodies and the oils and enzymes prevent
harmful bacteria into the human body.
7. Inflammation reaction of swelling happens when blood vessels leak fluid into the tissues. The
chemicals attract white blood cells (phagocytes) that eat germs and dead/ damaged cells. This
reaction prevents the spread of harmful toxins and pathogens to the rest of the human body
Mistake-proofing also occurs in natural systems and the human body system is a good example of how it works to
prevent errors from occurring.
43

44. Presented By:
PRANEET SURTI
https://www.linkedin.com/in/praneetsurti/
THANKS
References and images have been
taken from internet. 44