POKA YOKE

POKA YOKE

1. Error/Mistake

   • Mistake proofing, or its Japanese equivalent poka-yoke (pronounced PO-ka yo-KAY), is the use of any automatic device or method that either makes it impossible for an error to occur or makes the error immediately obvious once it has occurred. It is a common process analysis tool.https://asq.org/quality-resources/mistake-proofing

2. Types of mistake

   • Intentional
     • Are the mistakes made by not following regulations or policies.
   • unintentational
     • Mistakes arre made by worker errors such as : lack of experience, training, not having the ability to do the task.

3. Inspection

   • When a process step has been identified where human error can cause mistakes or defects to occur, especially in processes that rely on the worker’s attention, skill, or experience In a service process, where the customer can make an error which affects the output At a hand-off step in a process, when output (or for service processes, the customer) is transferred to another worker When a minor error early in the process causes major problems later in the process When the consequences of an error are expensive or dangerous https://asq.org/quality-resources/mistake-proofing

4. Poka Yoke

   • Concept
     • Poka-yoke (ポカヨケ, [poka yoke]) is a Japanese term that means "mistake-proofing" or "inadvertent error prevention". A poka-yoke is any mechanism in any process that helps an equipment operator avoid (yokeru) mistakes (poka).
   • Types of Poka Yoke
     • MOTION-STEP METHOD. The motion-step method is useful for processes requiring several different activities performed in sequence by a single operator. This is similar to the fixed-value situation in that the operator is responsible for multiple activities but instead of performing the same activity multiple times the operator performs different activities.
     • CONTACT METHODS. Contact methods are based on some type of sensing device which detects abnormalities in the product's shape or dimension and responds accordingly. Interference pins, notches with matching locator pins, limit switches and proximity switches are sometimes used to ensure that a part is positioned correctly before work occurs. Asymmetric parts with matching work fixtures can also alleviate incorrect positioning. If orientation is not critical, symmetrical designs can then be used to prevent defects.
     • Fixed-value Type Light sensors determine if each crayon is present in each box; if a crayon is missing, the machines will stop automatically. https://www.lbspartners.i

5. Types of Inspection

   • Judgement inspection also called as final inspection or standard inspection. It assesses quality of production outputs based on given sampling plans or sorts out defects from good products. This does not really improve the process & should be used only in short term as it only discovers defects. The two risks associated with sampling inspection is producer’s risk (rejecting a good lot of production) & consumer’s risk (accepting a defective product which gets dispatched to consumer). Informative inspection also called in-process inspection. It assesses process by inspecting outputs and using information gained to control the process (a feedback loop). This has relatively less risks & reduces the probability of defects to the extent of time interval between sampling. Source inspection Shingo, however, has recommended source inspection, i.e. assessing beforehand whether the conditions necessary for high quality production exist. This completely eliminates the possibility of mistakes. //ws