Poka yoke

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

6. 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

7. 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

8. 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

9. 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

10. 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.

11. 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

12. 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

13. 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

14. 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

15. 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

16. 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

17. 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

18. Examples of Poka Yoke Floppy Disk CD

19. Plug Pointer Syrup/ Tonic Examples of Poka Yoke

20. Parking Slot Traffic Signal Examples of Poka Yoke

21. Wash Basin Video Player Examples of Poka Yoke

22. Phone Battery Lodge Key Examples of Poka Yoke

23. 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

24. 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.

25. 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)

26. Mistake Proofing Types

27. Examples of Mistake proofing Devices

28. 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

29. 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.

30. 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.

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

32. 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 Code Lights

33. 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.

34. 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.

35. Thank you