Mistake Proofing (PokaYoke) Six Sigma Greenbelt Training Dave Merritt 1-18-17

The Six Sigma Cookbook Process Map Y Measurement System Analysis Y Focus Process Map Y Measurement System Analysis Y Process Capability Y Phase 1: Define/Measure Phase 2: Analyze Graphical Methods X’s Hypothesis Testing X’s Phase 3: Improve Analysis of Variance X’s Design of Experiments Vital Few X’s The analyze and improve phases help you understand your X’s (inputs) and to narrow down to the vital few X’s. Statistical Process Control Vital Few X’s Failure Mode and Effects Analysis Vital Few X’s Phase 1: Control

Learning Objectives By the end of this module, you will be able to: Understand the concept of Mistake Proofing as a control method Apply Poka-Yoke methods as a control on identified key Xs Reduce and/or eliminate process errors from occurring Reduce and/or eliminate process defects from occurring Understand “red flag” conditions

Why Is Mistake Proofing Important? Improves quality and customer satisfaction Prevents error occurrence Prevents defect occurrence If defects occur, ensures effective action Little or no formal training Cost effective Easy to implement In Summary: Mistake Proofing is one of the most cost effective and reliable controls that can be used to assure that our key input variables remain at our optimum project defined settings. 5 to 15 intervals Used to evaluate process capability of a stable process. If not stable – no central tendency See example with increasing trend.

What Is Mistake Proofing (Poka-Yoke)? Japanese phrase: Yokeru (to avoid), Poka (errors) A strategy for preventing errors in processes Makes it impossible for defects to pass unnoticed Prompts correction of problems as soon as they are detected Detects defects Prevents defects from moving into next area Developed by Dr. Shigeo Shingo to achieve zero defects

Common Examples Of Mistake Proofing Mechanical: Guide pins of different sizes Automated Optical Inspection (AOI) Limit switches Error alarms Asymmetric parts (square peg in round hole) Software: Field drop down menus for data entry Spell check Auto correct (really??) Weight and/or Quantity counters Required fields

Common Examples Of Mistake Proofing

Common Examples Of Mistake Proofing

Common Examples Of Mistake Proofing

Basics Of Mistake Proofing Effective Mistake Proofing requires 2 basic concepts: Controls the inputs that cause errors Inspection which is effective and tireless It IS NOT traditional 100% inspection by inspectors It IS a physical barrier that automatically performs the inspection with little to no human interaction A strong Poka-Yoke makes it nearly impossible for an error to occur. If one does occur, it is guaranteed to be detected. It can’t be passed into next area.

What Does Mistake Proofing Do? •The ideal process is Mistake Proofed at 3 points: Critical inputs into the process Within the process The output from the process will not accept any bad inputs will not make any bad parts will not pass on any bad parts

Classroom Exercise 1 – Round Robin Split into two teams: List a common Mistake Proofing idea from each of the following: • Home (ex. auto shut off on flat iron) • Car (ex. car won’t start unless transmission is in park/neutral) • Sport/Recreation (ex. dead man’s lanyard on treadmill) • Computer Software (ex. Spell check) 20 Minutes

Classroom Exercise 2 – Round Robin 2. The second time around, you will be asked to list possible Mistake Proofing ideas for each of the critical inputs into your project. 20 Minutes

Ten Common Reasons Mistakes Happen 1. Forgetfulness 2. Errors due to misunderstanding 3. Errors in identification 4. Errors made by untrained workers 5. Willful errors (ignore rules) 6. Inadvertent errors (distraction, fatigue) 7. Errors due to delay in decision making 8. Errors due to lack of standards 9. Surprise errors (malfunctions) 10. Intentional errors (sabotage)

Critical Inputs You will find in some projects, after you have identified the critical inputs and their optimal settings, one or more of them may be extremely difficult to control. Some examples: Training was found to be critical, but the operation has 150% turnover Cycle Times are very long, so the operators tend to lose concentration Finding ways to Mistake Proof in these situations would make your project successful

Common Examples of Ideal Mistake Proofing • Frequent changes to a job • Complex processes • Lack of standards • Lack of measurement systems • Lack of training • Long Cycle Times • Infrequent jobs • High output • Environmental conditions • Attitude (motivation)

Degree of Strength of Mistake Proofing Defective input is identified, operator altered and process stopped automatically. No product made with the bad input. Defective input is identified and operator alerted. Process detects input and alerts operator. Production continues. Best! Defective input is identified and operator alerted, but still allowed to enter into the process. Production continues. Good

Q & A