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What Does Poka-Yoke Mean?

poka-yoke

Have you heard the term Poka-Yoke and are wondering what it means? It’s quite simple. Poka-Yoke refers to ‘mistake proofing’ or “inadvertent error prevention”. 

It’s a Lean manufacturing mechanism designed to prevent mistakes from causing defects to products, services or processes. It’s a work standardization technique that can be applied to any manufacturing or service.

How does poka-yoke prevent mistakes from happening? By tackling human error. 

Origins of the term Poka-Yoke

Poka-Yoke originated in Japan in the 1960s when it was developed by Shigeo Shingo, an engineer working for Toyota. It was first called Baka Yoke but that meant ‘fool proofing’ or ‘idiot proofing’, which meant the term had to change to Poka (mistakes) Yoke (avoid).

How does Poka-Yoke work?

Poka-Yoke makes sure that all the best conditions are present before a process step is made and doing so prevents mistakes from ever taking place. Where the best conditions cannot be ensured altogether, Poka-Yoke detects defects and tries to remove them as early in the process as possible. 

Examples of Poka-Yoke being applied

One of the most easy-to-understand examples – especially for drivers – is when the driver of a car that has a manual gearbox has to press the clutch pedal before starting the car. This has to happen to stop any unintended movements of the car. 

Another easy-to-understand example is when a car with an automatic transmission has a switch that forces the car to be in ‘Park’ or ‘Neutral” before it starts. 

Another very basic example is when the washing machine doesn’t start without the door properly closed to prevent water from leaking out. These types of automation don’t allow mistakes or incorrect operations from the start. 

Why does Poka-Yoke matter?

Simple – because it helps people and processes function properly from the get-go, which in turn prevents mistakes from happening. 

Poka-Yoke and techniques similar to this one improve the quality and reliability of products, services and processes by removing defects altogether. 

The technique can also help with process designs such as those from Six Sigma – the DMAIC (Define – Measure – Analyze – Improve – Control) projects. Using Poka-Yoke in process design helps remove human and mechanical errors. 

When should Poka-Yoke be used?

  • When a process step has been spotted where human error can lead to mistakes and defects, specifically in processes that depend on the worker’s attention, expertise or experience
  • When dealing with service processes, especially where customers can make a mistake that affects the output
  • At a step in a process called the hand-off, where the output or the customer is transferred to a second worker
  • Where a small mistake at the beginning of a process can cause big projects further down in the process
  • When dangerous or expensive errors can happen

The Poka-Yoke mechanism is highly important and valuable in Lean Management. It’s a way to guarantee quality. It can be implemented in any type of industry with many benefits – the main one being products, services and processes without defects. 

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