Mistake proofing and prevention controls

Learning objectives

• Explain the purpose of mistake proofing and prevention controls in a garment-factory improvement project.
• Apply the described method to a representative shop-floor situation.
• Recognize the common mistakes and how to avoid them.

Concept

Mistake proofing makes an error impossible or detects it at the source before it becomes a defect.

Use physical constraints, orientation, interlocks, sequence checks, presence/count sensors, recipe locks, color/shape coding, and automatic stops.

Prefer eliminate/prevent over warn/inspect; extra final inspection is not poka-yoke.

Garment-factory example

A fixture prevents reversed label placement; a barcode recipe lock blocks the wrong wash program from starting.

Method

1. Identify error mechanism.
2. Choose control level (eliminate > prevent > detect > warn).
3. Prototype.
4. Challenge-test normal and abnormal cases.
5. Define bypass control and maintenance.

Common mistakes

• Calling extra final inspection poka-yoke.
• Allowing easy uncontrolled bypass of the device.