Lean Management: What is Poka-Yoke?

What is Poka-Yoke?

Poka-Yoke means fool proof which later called as mistake proof was coined by Shigeo Shingo in the 60s while working for Toyota. Poka-Yoke technique was use to prevent defect from occurring the first time. Poka-Yoke was apply in process at production floor after defects was identified to prevent it from happening. Poka-Yoke basically a simple low cost tools or device fabricate to fit its purpose.

Preventing error is crucial in process or service to avoid unnecessary cost incur. Error was identified through preventive process such as FMEA (Failure Mode and Effect Analysis).

What are Errors:

Process error - process which is missed or not performed as per SOP (standard operation procedure)

Set-up error - Wrong tool or machine setting.

Part Missing - Missing parts during assembly.

Improper part/item - Wrong part used or included in process.

Operation error - Wrong specification

Wrong measurement - error in machine calibration, adjustment, wrong test or measurement.

Poka-Yoke Type:

shut out type - prevent an error being made

attention type - highlight error (eg. limit switches, automatic shut-off)

electrical, mechanical, procedural, visual, human or any other form that prevention to avoid error in processing.

The use of poka-yoke can eliminate both human or technical error. This tool is part of lean management when apply could improve design and process efficiency and increase product quality.

Examples of everyday Poka-Yoke:

Card slot at ATM (notice that the machine can only accept card when enter correctly)
High speed camera system on production floor to identify wrong parts.
Edge guides to prevent rolls goes off tracks.
Sensor to stop machine if product was distorted.
Template used at production floor to identify missing parts.
Car reverse sensor.
Shut-off valve when liquid meet certain pressure/air flows.
Go-no-go gauges for testing purposes
Laser curtain
Temperature sensors