5 3.5 DisketteCannot be inserted unless diskette is oriented correctly. This is as far as disk can be inserted upside-down. The beveled corner of the diskette pushes a stop in the disk drive out of the way allowing the diskette to be inserted. This feature, along with the fact that the diskette is not square, prohibit incorrect orientation.
6 File CabinetsCan fall over if too many drawers are pulled out. For some file cabinets, opening one drawer locks all the rest, reducing the chance of the file cabinet tipping.
7 Bathroom SinksEven bathroom sinks have a mistake-proofing device. It is the little hole near the top of the sink that helps prevent overflows.
8 Key HolderIn China, where electric power has been scarce, hotel rooms are equipped with a room key holder which turns off the power when the key is removed. This ensures no electricity flow to the room while it is vacant.
9 ATM MachinesNew generation ATMs perform transactions without the card leaving your hand because of the beeping sound once your card comes out of the machine
10 ElevatorsMany elevators are equipped with an electric eye to prevent doors from shutting on people. They also are equipped with sensors and alarms to prevent operation when overloaded.
11 Why Poka-Yoke?FACT!Workers finish their shift & don’t remember what they have doneEven highly skilled workers get tired and start committing mistakesWorkers get distracted and forget on a valve or switch
12 TIPCO Experience Incidental Details Root Causes Chemical valve at kneading machine left openWrong delivery to customerUnaccounted requisition causes distorted inventory stockOverflow of whitewater storage tankHuman ErrorWrong label generated and pasted on rollMisplaced actual stock requisition formUnable to monitor level
13 TIPCO Experience Incidental Details Root Causes Delay at truck scale Fresh water tank emptiedTruck ran out of fuelForgot to put the control value to auto after cleaning the strains
15 Kinds of Human Errors Forgetfulness Misunderstanding We forget things when we are not concentratingMisunderstandingWe make mistakes when we jump to conclusion before we are familiar with the situation
16 Kinds of Human Errors Identification Made by Amateurs We misjudge a situation because we view it too quickly or are too far away to see it clearly.Made by AmateursWe make mistakes through lack of experience
17 Kinds of Human Errors Willful Errors Inadvertent Errors We decide that we can ignore rules under certain circumstancesInadvertent ErrorsWe are absentminded and we make mistakes without knowing how they happened
18 Kinds of Human Errors Due to Slowness Lack of Standards We make mistakes when our actions are slowed by delays in judgementLack of StandardsErrors occur when there are no suitable instructions or work standards
19 Kinds of Human Errors Surprise Errors Intentional Errors Equipment runs differently than expectedIntentional ErrorsWe make mistakes deliberately
20 How to deal with errors Errors happen Errors can be eliminated “Errors are inevitable. The mark of character is not refusing to recognize them, but acknowledging them and taking responsibility.”Errors can be eliminatedPeople make fewer mistakes if they are supported by proper training and by a production system based on the principle that errors can always be prevented.
21 5 Best Poka Yoke Guide pins of different sizes Error detection and alarmsLimit switchesCountersChecklists
24 Sampling vs 100% Inspection Sampling inspection“we maintain our quality at 99%”100% Inspection“we won’t tolerate a single defect.”
25 3 Strategies for ZD Don’t make it! Make it to withstand any use! The more products you make, the greater opportunity for defects to sit in inventory.Make it to withstand any use!Build safeguards into the production process to ensure that the product is robust from the user’s viewpointOnce you’ve made it, use it right awayGo for continuous flow production
26 Inspection Techniques Judgment InspectionSeparates defective products from good ones after processingInformative InspectionUses data feedback to control the process and reduce the defect rate.Source InspectionDetermines before the fact whether the conditions necessary for high quality production exist.
27 Prediction vs Detection System acts before a defect occursDetectionSystem does not allow continuation
28 Basic Poka Yoke Functions ShutdownNormal operations are stopped when defect is detected or predictedControlPrevents defective items from passing on the next processWarningSystem signals when an abnormality is about to occur or that a single defect has already occured
29 Basic Poka Yoke Functions ShutdownNormal operations are stopped when defect is detected or predictedControlPrevents defective items from passing on the next processWarningSystem signals when an abnormality is about to occur or that a single defect has already occured
30 Where “Mistake-Proofing” works well Manual operations were worker vigilance is neededWhere mispositioning can occurWhere adjustment is requiredWhere SPC is difficult to applyWhere special causes can reoccurWhere external failure costs dramatically exceed internal failure