Empowering Lean Solutions for Everyone

Poka Yoke

 Poka Yoke Definition

What is the meaning of Poka Yoke?

  • Techniques that help operators avoid mistakes in their work caused by choosing the wrong part, leaving out a part, installing a part backwards, etc.
  • It involves the implementation of fail-safe ways methods that detect or prevent human and machine error at or near the source
  • It provides instant feedback and prevention of quality problems

Definition of a Defect

  • The result of any deviations from product specifications that lead to customer dissatisfaction

Definition of an Error

  • Any deviation from a specified manufacturing process
  • The result of an error is shown in a defect.

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

Detection Device

  • Is a device that will detect a defect or concern and initiate a corrective action
  • Examples: vision system, limit sensors

Causes of Errors

What cause errors? Here are some of the most common causes.

  • Processing omissions
  • Processing errors
  • Error in setting up the work piece
  • Missing parts
  • Improper item
  • Processing wrong work piece
  • Operations errors
  • Adjustment, measurement, dimension errors
  • Errors in equipment maintenance/repair
  • Errors in preparation of tools/jigs
  • Adjustments
  • Tooling and tooling changes
  • Dimensions/specifications
  • Many mixed parts
  • Multiple steps
  • Infrequent production
  • Lack of an effective standard
  • Symmetry
  • Asymmetry
  • Rapid repetition
  • High volume
  • Environmental conditions

Poka Yoke Implementation

  • Develop team
  • Create Error Proofing Implementation Sheet
  • Identify and describe defect
  • Determine location the defect was found & made
  • Identify root cause
  • Current process and deviations from standards
  • Propose and implement improved process
  • Measure
  • Standardize

Guidelines for Poka Yoke or Error Proof Devices

  • Low cost, easy to implement
  • Prevent the ability to make a defect / prevent the defect from being passed on
  • Provide immediate feedback