2 INTRODUCTIONThe old way of dealing with human error was to scold people, retrain them, and tell them to be more careful next time.Much cannot be done to change human nature, and people are going to make mistakes.If human errors cannot be tolerated, then the opportunities for error should be removed.Training and motivation work best when the physical part of the system is well designed.If people are trained to use poorly designed systems, they will abide for a while, but consciously or unconsciously they will go back to their norms or that they feel easy, instead of doing what is safe.If the system can be improved so that the easy way to do a job is also the safe, right way, then potential for human error can be drastically reduced.
3 WHAT IS ERROR/MISTAKE Acts of commission and /or omission by human due Lack of concentrationPoor understanding of basisLaziness by finding short ways (cutting corners)SabotageGenerally, error mean deviation from what is correct, right, or true.Error can be deliberate (sabotage) or not deliberate (mistake)
4 WHAT CAUSES DEFECTS?All errors leads to defects in materials, products, services, equipment, specifications and standardsThese error emanate from: Poor procedures or standards, Machines, Non-conforming materials, Worn tooling, Human MistakesExcept for human mistakes, other types or sources of errors can be predicted and corrective action can be implemented to eliminate the cause of defects.To avoid such mistakes here comes the tool that is called POKE-YOKE
5 HISTORY Pronunciation: POH-KAH-YOH-KAY YOKERU Avoid , POKA Mistakes Coined in Japan during the 1960s Shigeo by as Shingo part of the Toyota Production System.Initially „BAKA-YOKE‟ „fool-proofing‟ Dishonorable and offensive Changed to „POKA-YOKE‟ „mistake- proofing‟
6 GOAL OF POKE YOKEMistakes are inevitable; people are human and cannot be expected to concentrate all the time on the work in front of them or to understand completely the instructions they are given.Defects result from allowing a mistake to reach the customer, and defects are entirely avoidable.The goal of Poka-Yoke is to engineer the process so that mistakes can be prevented or immediately detected and corrected
7 POKA YOKE CONCEPTS Poka Yoke as Prevention Device: Is a device or process that prevents errors from occurring or prevents these errors from creating defects. Examples: part locators, part present sensors.This is done is such a way that allow operators to avoid mistakes in their work (such caused by choosing the wrong part, leaving out a part, installing a part backwards, etc.)Poka Yoke as Detection Device:Is a device that will detect a defect or concern and initiate a corrective action. Examples: vision system, limit sensorsInvolves the implementation of fail-safe ways methods that detect or prevent human and machine error at or near the source.Both provides instant feedback and prevention of quality problems
8 POKA YOKE CONCEPTSIt is a technique, a tool that can be applied to any type of process be it in manufacturing or the service industry.Poka-yoke can be used wherever something can go wrong or an error can be made.Processing Error: Process operation missed or not performed.Setup Error: Using the wrong tooling or setting machine adjustments incorrectly.Missing Part: Not all parts included in the assembly, welding, or other processes.Improper part/item: Wrong part used in the process.Operations Error: Carrying out an operation incorrectly; having the incorrect version of the specification.Measurement Error: Errors in machine adjustment, test measurement or dimensions of a part coming in from a supplier.
9 HOW TO USE IT Step by step process in applying poka-yoke:- Identify the operation or processAnalyze the 5-whys and understand the ways a process can fail.Decide the right Poka-yoke approach, such as using a, Shut out Type: Preventing an error being made, or an Attention Type: Highlighting that an error has been made.Determine whether a Contact Method Constant Number or Counting Method Motion-Sequence Method.Trial the method and see if it works.Train the operator, review performance and measure success.
10 HOW TO USE IT Contact Methods:- These can be as simple as blocks that do not allow parts to be seated in the wrong position prior to processing.Take advantage of parts designed with an uneven shape.This method signals to the operator right away that the part is not in proper position.Constant Number or Counting Method:-Used when a fixed number of operations are required within a process.When a product has a fixed number of parts that are attached to it.A sensor counts the number of times a part is used or a process is completed and releases the part only when the right count is reached.
11 HOW TO USE IT Motion-Sequence Method:- The third poka yoke method uses sensors to determine if a motion or a step in a process has occurred.If the step has not occurred or has occurred out of sequence, the sensor signals a timer or other device to stop the machine and signal the operator.
12 EXAMPLESDisk, Mobile SIM slot, USB slot: diskettes cannot be inserted unless diskette is oriented correctly. This is as far as a disk can be inserted upside-down. The beveled corner of the diskette along with the fact that the diskette is not square, prohibit incorrect orientation.
13 EXAMPLESFile cabinets: opening one drawer locks all the rest, reducing the chance of the file cabinet tipping.Circuit breakers prevent electrical overloads and the fires that result. When the load becomes too great, the circuit is broken
14 EXAMPLESSinks: bathroom sinks have a mistake-proofing device. It is the little hole near the top of the sink that helps prevent overflows.The urinal are fitted with light sensors. These sensors insure that the water is turned off in the sink and that the urinal is flushed.
15 EXAMPLES Microwaves Washing machines Central locking in modern cars Key locks in mobilesRefrigeratorsBeeps in automobiles if key is left in ignitionElectronic appliances socketsSubmarine: The bathyscaph is a deep water submarine used to explore the very lowest parts of the ocean. It is electrically powered. Once at the bottom, if the batteries or electrical system fail the best outcome would be for the sub to return to the surface. The designers made this outcome occur by holding the ballast in place with electromagnets. When power is lost, the ballast drops off automatically and the sub starts its ascent.
16 WHY IS IT IMPORTANTHelps people and processes work right the first time.Refers to techniques that make it impossible to make mistakes.Helps drive defects out of products and processes and substantially improve quality and reliability.Used to fine tune improvements and process designs from six-sigma Define - Measure - Analyze - Improve - Control (DMAIC) projects.Use the ideas and methods in product and process design which can eliminate both human and mechanical errors.
17 CHARACTERISTICS OF POKE-YOKE Simple and cheapPart of the process, permitting 100% inspectionPlaced close to where the mistakes occur, providing quick feedbackDesigned to stop a particular mistakeReflection: To err is human nature but intelligence is also human nature so never stop finding ways of not making mistakes