Apr 12, 2023 www.leanteamsusa.com 1

Robert BairdPresident

+1 215 353 0696

Error Proofing

Apr 12, 2023 www.leanteamsusa.com 2

Error Proofing a new mindset

Even one defective product can cause a company a lot of business

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What causes defects

Cultural factors• Wrong procedures

or standards are applied

• People expecting and accepting defects

Variance• Material variation

(thickness, finish, etc.)

• Worn machine parts• Input drifting

Complexity• Too many steps• Many input

variables• Unique knowledge

Mistakes• Humans – errors

because of poorly designed systems

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Some Solutions

Cultural• Management

commitment and support

• Empowered Teams • Standard Work

Variance• TPM• Six Sigma methods • Supplier partnerships• DFOEE

Complexity• Value stream

mapping• Technology • input variable

standards• Knowledge sharing

Mistakes• Mistake proofing,

Poke-Yoke• Near miss program• System thinking

To err is human

Have you ever done the following:

• Driven to work and not remembered certain events?

• Driven from work to home when you meant to stop at a store?

It happens to workers too

• Workers finish the shift and don’t

remember what they have done.

• After building green widgets all morning, the workers put green parts on the red widgets in the

afternoon.

It doesn’t work

• Majority of corrective actions reported at least 20-30% of corrective actions were worker reprimanded and retraining

• The warning to be more careful or

pay attention are not effective for humans, especially in repetitive environments.

This Does Work

• Stop blaming the human. Correct the system!• Make wrong actions more difficult or impossible.

• Source inspection Vs Judgment Inspection

• Make it easier to detect the errors that occur.

• Make incorrect actions correct.

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Evolved inspection

JudgmentInspection

Sorting the bad from the good

InformativeInspection

Feedback to the source for corrective action

SourceInspection

Prevent the defect from happening

100% inspection by mechanical sensors

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Inspection Locations

Pro

cess

Input

200 – 220 F

3000 units/hr

830 – 840 micron

12345678910codeification

Value-add

On time

Output

Defective product

Judgment

Informative

Source

Feedback

Ensures conditions are in place before hand to perform a process properly

Dr. Shigeo Shingo warned that you couldn’t force the speed of the production system. Error Proof techniques to Correct Defects + Source Inspection to Prevent Defects = Zero Quality Control. This equation is the essence of the Zero Quality Control Concepts.

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Error Proofing Levels

Level Prevention Detection

1. Force ControlNo human intervention

Physical contactor, electronic control prevents the mistake from being made

Physical contact or electronic control prevents the mistake from getting to the customer

2. Shutdown The process is shutdown before the mistake can be made

The process is shutdown immediately after a mistake is detected

3. Warning A warning light or audible alarm signals that a mistake is about to be made

A warning light or audible alarm signals that a mistake has just been made

4. Sensory Alert A visual or other sensory cue is given that a mistake is about to be made

A visual or other sensory cue is given that a mistake was just made

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Common Mistake-proofing Devices

Guide Pins

Blinking lights and alarms

Limit switches

Proximity switches

Counters

Checklists

Vision system

Software

We Provide Guidance, Training, and Support

• Lean Teams USA Lean Consulting

• View My Profile on LinkedIn

• Lean Teams USA +1 215 353 0696

• @Robertbaird10

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