QUALITY TOOLS Poka-Yoke (Mistake Proofing): QUALITY TOOLS Poka -Yoke (Mistake Proofing) What Poka-Yoke Means: What Poka -Yoke Means Poka -Yoke was developed by Shigeo Shingo from Toyota Motors as a tool to achieve Zero Defects. • The process of Zero Defects is also known as “Mistake Proofing” or “Fail-Safe”. • By taking over repetitive tasks or actions that depend on vigilance or memory, Poka -Yoke can free workers’ time and mind to pursue more value added activities. PowerPoint Presentation: Why is “Zero Defects” an Important Concept? Maintain Customer Satisfaction & Loyalty Happy Customers mean more sales! COST There is always a cost associated with manufacturing defects! PowerPoint Presentation: Costs of Defects ? Does it cost more to make processes better ? NO Making processes better leads to reduced Rework Scrap Warranty costs Inspection costs PowerPoint Presentation: 1-10-100 Rule The 1-10-100 rule states that as a product or service moves through the production system, the cost of correcting An error multiplies by 10. Activity Cost Order entered correctly Rs 1 Error detected in billing Rs 10 Error detected by customer Rs 100 Dissatisfied customer shares the experience with others the costs is Rs 1000 PowerPoint Presentation: 6 What is a Zero Defect Quality System (ZDQ)? A quality concept to manufacture ZERO defects & elimination of waste associated with defects! “ ZERO” is the goal! PowerPoint Presentation: What is a Zero Defect Quality System (ZDQ)? Based on a discipline that defects are prevented . Control the process so that defects/errors are impossible! Two options for Removing Defects: Two options for Removing Defects Demand vigilance. Exhort workers to “be more careful!” Mistake-proof. Eliminate the chance of making the mistake Are Errors Unavoidable?: Are Errors Unavoidable? There are two approaches to dealing with errors: 1. ERRORS ARE INEVITABLE! 2. ERRORS CAN BE ELIMINATED! 1. Errors Are Inevitable: 1. Errors Are Inevitable People always make mistakes. While we accept the mistakes as natural, we blame the people who make them. With this attitude, we are likely to overlook defects as they occur in production. They may be detected at final inspection, or worse still, by the customer. 2. Errors Can Be Eliminated: 2. Errors Can Be Eliminated Any kind of mistake people make can be reduced or even eliminated. People make fewer mistakes if they are supported by proper training and by a production system based on the principle that errors can be avoided. 10 Mistakes Human Mistakes: 10 Mistakes Human Mistakes Forgetfulness Misunderstanding Wrong identification Lack of experience Willful (ignoring rules or procedure) Inadvertent or sloppiness Lack of standardization Surprise (unexpected machine operation, etc.) Intentional (sabotage) Poka-Yoke: Poka -Yoke Recognize that it is natural for people to make mistakes. Not noticing that an error is made or a machine is not functioning does not make a person stupid or foolish. No finger pointing after the fact. No mandate to do better next time. Some Background on Inspection : Some Background on Inspection Traditionally, quality is inspected quality . • Judgment Inspection: Separating good from bad after processing. • Informative Inspection: Inspect then take action to eliminate future occurrence. • 100% or Sampling inspection based on SPC (Statistical Process Control) methodologies. Inspection: • assumes defects are inevitable. • believes the process of inspection will reduce defects. • can reinforce ‘quality’ is responsibility of the quality department. • is not 100% effective. All of the above tolerate some level of defects. How do we achieve 0 defects? Basic Function of Poka-Yoke : Basic Function of Poka-Yoke A defect exists in one of two states: 1. it is about to occur 2. it has already occurred Three basic poka -yoke functions to use against defects: 1. SHUT DOWN a machine or operation 2. CONTROL a process or operation 3. WARN that a defect has occurred Recognizing that a defect is about to occur is called PREDICTION. Recognizing that a defect has happened is called DETECTION. Poka-Yoke Culture : Poka -Yoke Culture Focus on building quality into the process. remember to consider the sources of variation, engage GB and BB support. make it impossible to create a defect. Believe that inadvertent errors can be eliminated. • engage the people in the process. • 10 heads are better than one. Implement the best ideas after you find the root cause • chase through the five ‘why’s’, then …. Brainstorm to get to the best solution to attack root cause. No more excuses! Build a culture that finds a way to do it right the first time and does not tolerate errors ! Attitude toward Preventing Errors: Attitude toward Preventing Errors Make wrong actions more difficult Make it possible to reverse actions —to “undo” them—or make it harder to do what cannot be reversed. Make it easier to discover the errors that occur. Make incorrect actions correct. To prevent mistakes, develop error proofing devices POKA-YOKE to avoid (yokeru) inadvertent errors (poka): To prevent mistakes, develop error proofing devices POKA-YOKE to avoid ( yokeru ) inadvertent errors ( poka ) Checklists Error & alarm detectors Limit or touch switches Detectors, readers, meters, counters Poka-Yoke Examples : Poka -Yoke Examples Shutdown/Warning (Detection): The compact disc will only work in one orientation. Example: Example Error: esophageal intubation (putting a tube into a patient’s stomach which was intended for their lungs) Poka -Yoke: Squeeze bulb and put on tube. If bulb inflates, the tube is in the lungs. If not, tube is incorrectly placed in the esophagus. PowerPoint Presentation: Graphical user interfaces are all about mistake-proofing. Remember the DOS error message: Bad Command or File Name? It can't happen when you point and click from a list. Whose signature is required?: John Grout Whose signature is required? Before: After: Knowledge in the World: PowerPoint Presentation: The manufacturer has rigged this drill to stop immediately when the bit contacts any grounded or electrically live materials so you can't drill through hidden pipes or wiring. PowerPoint Presentation: Gas pumps are equipped with hose couplings that break-away and quickly shut-off the flow of gasoline. PowerPoint Presentation: This automatic coffee pot is equipped with a “pause and serve” feature. The lid of the pot presses up on the button (shown at right above), releasing a valve which allows the coffee to pour into the pot. If you remove the pot before brewing is finished, the valve closes so coffee is not spilled. PowerPoint Presentation: My safety harness buckle has a red mark indicating that it has not been locked (incorrect). When the buckling is complete the red mark is covered. PowerPoint Presentation: British 240v/50Hz electricity can injure people so electrical plugs are designed so that live electrical pins are never exposed. Which dial turns on the burner? Which stove is better designed?: Which dial turns on the burner ? Which stove is better designed? Stove A Stove B How would you operate these doors? : How would you operate these doors? B A C Push or pull? left side or right? How did you know?