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What is it: Poka-Yoke - 'mistake-proofing', is a Japanese term which means mistake proofing to prevent errors from occurring or recurring. A Poka-Yoke device is one that prevents incorrect parts from being made or assembled, or easily identifies a flaw or error. Often referred to as 'error-proofing', Poke-Yoke is actually the first step in truly error-proofing a system. Error-proofing is a manufacturing technique of preventing errors by designing the manufacturing process, equipment, and tools so that an operation literally cannot be performed incorrectly.

Why use it: The goal of mistake-proofing or Poka-Yoke is to eliminate mistakes. In order to eliminate mistakes, we need to modify processes so that it is impossible to make them in the first place. With mistake-proofing solutions, many repetitive tasks that depend upon the memory of the worker are built into the process itself. Mistake-proofing frees the time and minds of the workforce to pursue more creative and value-adding activities. Mistake-proofing also involves a change in the mindset of the organization. Organizations must establish a mistake-proofing mindset that promotes the belief that it is unacceptable to allow for even a small number of product or service defects. The following are usually accomplished with Poka-Yoke:

  • Improved Productivity
  • The Highest Achievable Levels of Quality
  • The Fastest Way to Zero Defects
  • A Key Enabler for Efficient Manufacturing
  • Virtually eliminates Scrap, Rework, and Repair
  • Lowest Cost Quality Control
  • Minimizes Inventory
  • Customer Loyalty

Where to use it: Poka-Yoke (Error and Mistake Proofing) can be focused on a single machine or or it can become a broad undertaking, addressing many issues simultaneously.

When to use it:

  • 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.

How to use it: 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. The process usually follows the following guidelines:

  1. Obtain or create a flowchart of the process. Review each step, thinking about where and when human errors are likely to occur.
  2. For each potential error, work back through the process to find its source.
  3. For each error, think of potential ways to make it impossible for the error to occur. Consider:
    • Elimination—eliminating the step that causes the error.
    • Replacement—replacing the step with an error-proof one.
    • Facilitation—making the correct action far easier than the error.
  4. If you cannot make it impossible for the error to occur, think of ways to detect the error and minimize its effects. Consider inspection method, setting function and regulatory function.
  5. Choose the best mistake-proofing method or device for each error. Test it, then implement it

Poka-Yoke either give warnings or can prevent, or control, the wrong action. It is suggested that the choice between these two should be made based on the behaviors in the process, occasional errors may warrant warnings whereas frequent errors, or those impossible to correct, may warrant a control Poka-Yoke.

Important Notes:

  • If you are experiencing high levels of scrap and rework, error and mistake proofing provides pinpoint focused tools that will help you quickly remedy these problems and dramatically reduce production losses.
  • There are four levels of mistake-proofing, forced control, shutdown, warning, and sensory alert; and two outcomes, prevention and detection. The best mistake-proofing solution is a forced control-prevention one.
  • Forced control and shutdown solutions have automatic triggers so they are much superior to warning and sensory alert solutions.

Preview (Click to enlarge)
  Poka-Yoke Instructions
Adobe PDF Format
Adobe PDF
Poka-Yoke Instructions
  Mistake Proofing Analysis Form
Microsoft Excel Format
Microsoft Excel
Mistake Proofing Analysis Form
  Poka-Yoke Blank Worksheet Template
Microsoft Excel Format
Microsoft Excel
Poka-Yoke Blank Worksheet Template
USD $19.95
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