Poka Yoke Types, Approaches, Sensors and Some examples are described in the presentation.

1. Presented by
S.Sanjay (18MF32)
POKA YOKE

2. Contents
• Poka yoke Introduction
• Defects and Impacts
• Typical errors
• How to use Mistake proofing
• Poka Yoke System
• Examples of Poka yoke
• Approaches of Poka Yoke
• Poka Yoke types
• Sensing Devices
• Advantages

3. Introduction
• Poka’ means ‘Mistakes’ & ‘Yoke’ means ‘Avoid’. It’s objective is to
achieve Zero Defects.
• Quality assurance technique ,
• Aim - to eliminate defects in a product by preventing or correcting
mistakes as early as possible.
• Term adopted by Dr. Shigeo Shingo as part of the Toyota Production
System in 1960.
• It was originally described as “baka-yoke”, but this name mean “Fool-
Proofing”.

4. Defects And Its Impact
• Defect free product is a necessity to compete in the market place.
• Every Customers has a right to demand 100% good product /service
and every provider has an obligation to provide the same.
• Bad products hurt both reputation and bottom line (Scrap, rework,
warranty….etc.,.)
• Defects have a direct impact on process yield affecting speed and
flow of the product to the customer.

5. Typical Errors
 Processing errors
 Missing Operation
 Inappropriate procedures
 Missing parts
 Missing information
 Wrong parts
 Damaged materials
 Tools or equipment
improperly prepared or setup
 Human Errors

7. How To Use Mistake Proofing?
• Identify the process.
• Process can fail
• Decide right poke yoke approach
• Use of checklist
• Trail the method
• Train the operator

8. Poka-Yoke System
A. Awareness (Brainstorming, Communication, Measurement)
B. Root Cause Analysis (The Five Why’s, Brainstorm & Prioritize
Causes)
C. Six Poka-Yoke Techniques
1.Elimination
2.Replacement
3.Prevention
4.Facilitation
5.Detection
6.Mitigation

9. Awareness
• The First Step of Poka-Yoke is “AWARENESS”
 Brainstorm what has gone wrong and/or could go wrong
 Communicate possible errors
 Measure actual errors and post on communication boards
 Run charts on safety performance, quality issues, scrap, rework,
customer complaints, etc.
 Pareto Analysis (80/20 Rule) of Past Performance
 Routinely review performance and ask for ideas for improvement

10. Root Cause Analysis
• The Second Step of is “Root Cause Analysis” The 5 Why’s
 List the mistake/error at the top
 Ask why the problem occurs and record answers (if too many answers
are generated, prioritize the list to a manageable number)
 For each answer, ask why it occurs and record answers
 Keep asking why (approximately 5 levels) for each answer to get to the
true root cause(s) of the problem
 Stay within range of possible solutions by continually asking, “Can we
fix this problem?”
 Be alert to drifting away from practical solutions

11. Five Why’s Example Problem
Solution: Fix the hole in the roof.
S.No Questions Answers
1. “Why are we replacing the tires?” They get flat all the time.
2. Why do they get flat? They get nails in them.
3. Why do they get nails? There are nails on the floor.
4. Why are there nails on the floor? Nails fall out of their wet
cartons.
5. Why are the cartons wet? There is a hole in the roof.

14. Solutions to Address Causes
• The Third Step of Poka-Yoke is “Solutions to Address Causes”
• The Six Mistake-Proofing Techniques/ Principles/ Methods:
1. Elimination
2. Replacement
3. Prevention
4. Facilitation
5. Detection
6. Mitigation

15. Elimination
Description:
- Eliminate the step that causes the mistake
- Remove Non-Value Added activities
- Redesign the product or process
Examples:
- Replace manual data entry with computerized download
- Eliminate unneeded processing step that is allowing contamination
to occur

16. Replacement
Description:
- Replace the step with a more reliable mistake-proof one
- Automation of repetitive motion activities
Examples:
- Welding robotics for automobile manufacturers
- Automatic letter scanners and sorters
- Copy machines with collating and stapling
features

17. Prevention
Description:
- Change product or process so that mistake is impossible
- Physical barrier or fit to prevent undesired action
Examples:
- Guards on moving equipment
- Plugs for 110V & 220V
- Printer cartridges
- Go/No Go Gauges

18. Facilitation
Description:
- Make the correct action far easier than the mistake
- Visual controls like color coding, labels, lines and signs
Examples:
- Warning signs
- Checklists
- Traffic lane markings
- Color coded parts or tools

19. Detection
Description:
- Make mistakes obvious for immediate correction
- Sensors, limit switches, light sensors
Examples:
- Safety guard limit switches to prevent machine running when open
- Set number of parts to install; if there are any left over, then it was
missed
- Computer warning if all information is not filled in

20. Mitigation
Description:
- Minimize the effects of mistakes
- For when the mistake cannot be eliminated
Examples:
- Personal protective equipment
- Air bags in cars
- Electrical fuses
- An eraser on a pencil

23. Examples of Poka Yoke
Floppy Disk CD

24. Plug Pointer Syrup/ Tonic
Examples of Poka Yoke

25. Parking Slot Traffic Signal
Examples of Poka Yoke

26. Wash Basin Video Player
Examples of Poka Yoke

27. Phone Battery Lodge Key
Examples of Poka Yoke

28. Approaches To Mistake Proofing
 Control approach
 Shuts down the process when an error occurs
 High capability of achieving zero defects (ie robust design that can
tolerate variation or eliminates variation or assembly mistakes)
 Warning approach
 Signals the operator to stop the process and correct problem or check
for a problem (ie are parts still ok, is oil level ok)
 Sometimes an automatic shutoff is not an option
 Dials, lights, and sounds to bring attention to the problem

29. Control Approach Examples
Electronic door locks can have three
mistake-proofing devices:
• Insures that no door is left unlocked.
• Doors automatically lock when the car
exceeds 18 miles an hour.
• Lock won't operate when door is open and
the engine is running.
Manhole covers are round because if they
were of any other shape (Ex: Square) it
would be possible to accidentally drop
one through the hole while removing it.

30. Example of Warning Approach
Warning lights alert the driver of potential problems. These
devices employ a warning method instead of a control method.
(Seatbelts, High engine temperature, Low oil pressure)

31. Mistake Proofing Types
• Makes contact with every product or has a physical
shape that inhibits mistakes.
• Example: Fixed diameter hole through which all
products must fall and an oversize product does not
fall through and a defect is registered.
Contact type
• Design that makes it clear when a part is missing or
not used.
• Example: “Egg tray” used for supply of parts,Fixed value type
• Automatically ensures - correct number of steps
• Example: An operator is required to step on a foot
pedal every assembly cycle, Correct sequence for
switches that do not work unless the order is correct.
Motion step type

32. Examples of Mistake proofing Devices
Guide
pins
• Assure that parts can only be assembled in the correct way.
Limit
switches
• Sense the presence or absence of a part.
Jigs
• Detect defects immediately upstream of the process ensuring
that only the correct part reach the process.
Counters
• Verify that the correct number of parts or steps have been
taken.
Checklist
• Reminds operators to do certain actions.

33. Types Of Sensing Devices
• Sensing devices that are traditionally used in poka-yoke systems can
be divided into three categories:
1. Physical contact devices
2. Energy sensing devices
3. Warning Sensors

34. Physical Contact Sensors
• Works = physically touching
something.
• This can be a machine part or an
actual piece being manufactured.
• These devices send an electronic
signal when they are touched.
• Depending on the process, this
signal can shut down the operation
or give an operator a warning
signal.

35. Touch Switch
• Used to physically detect the
presence or absence of an object or
item-prevents missing parts.
• Used to physically detect the
height of a part or dimension.

36. Energy Sensors
• These devices work by using
energy to detect whether or not
an defect has occurred.
Fiber optic
Photoelectric
Vibration

37. Warning Sensors
• Warning sensors signal the
operator that there is a problem.
• These sensors use colors,
alarms, lights to get the workers
attention !
• These sensors may be used in
conjunction with a contact or
energy sensor to get the
operators attention.
Lights connected to Micro switches & timers
Color CodeLights

38. The Seven Guidelines to Poka- Yoke Attainment
• Quality Processes - Design “Robust” quality processes
• Utilize a Team Environment- leverage the teams knowledge & experience
• Elimination of Errors -Utilize a robust problem solving methodology
• Eliminate the “Root Cause” of The Errors
• Do It Right The First Time- Utilizing resources correctly the “first” time.
• Eliminate Non-Value Added Decisions- Don’t make excuses-just do it
• Implement an Incremental Continual Improvement Approach- efforts do
not have to result in a 100% improvement immediately.

39. Advantages of Poka yoke
• Without involving much effort, it performs 100% assessment.
• Discovers and eradicates defects.
• Creates a process of consecutive verification for each procedure.
• Presents self-check actions which provide quicker review
• Doesn’t just identify the causes of errors but eliminates the causes
• Elimination of defects ultimately increases customer satisfaction.
• The focal point is on waste reduction in defects and processing.

40. Thank you