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INTRODUCTION

What is a Poka- yoke?

Shigeo shingo defined poka-yoke as POKA- ‘Inadvertent mistake that anyone can make’ and YOKE- ‘To prevent or proof’

Poka-yoke is a tool to have “zero defects” and even reduce or eliminate quality control.

Poka-yoke is a Japanese name for “fool-proofing”.Poke-yoke represents the intelligence of the

operator by excluding repetitive actions that require a thinking process.

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MISTAKE PROOFINGMistake-Proofing a product's design and its

manufacturing process is a key element of design for manufacturability / assembly (DFM/A)

Mistake proofing is also a key element of improving product quality and reliability

FACTORS CONTRIBUTING TO MISTAKE PROOFING:AttentionPerceptionMemoryLogical reasoning

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PRINCIPLES OF MISTAKE-PROOFING There are six mistake-proofing principles or

methods. Elimination seeks to eliminate the possibility of error

by redesigning the product or process so that the task or part is no longer necessary.

Replacement substitutes a more reliable process to improve consistency.

Prevention engineers the product or process so that it is impossible to make a mistake at all.

Facilitation employs techniques and combining steps to make work easier to perform.

Detection involves identifying an error before further processing occurs so that the user can quickly correct the problem.

Mitigation seeks to minimize the effects of errors. April 10, 2023 4

2-STATUS & 3-FUNCTIONS OF POKA-YOKE

POKA-YOKE HAS 2 STATUS AND 3 FUNCTIONS:

Status: 1.The fault will happen or 2.The fault has happenedFunctions: 1.Stop 2.Check or 3.Alarm

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THREE STRATEGIES FOR ZERO DEFECT

Only make the product when required!

Make the product so it can not be used for anything else.

If the product is ready use it immediately.

 

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POKA-YOKE CLASSIFICATION

Poka-yoke is classified into the following types:

Server Poka-Yokes

Task

Treatment Tangibles

Customer Poka-Yokes

Preparation

Encounter

Resolution

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PROVIDER(SERVER) ERRORSTask Errors

• Doing the work incorrectly• Doing work not requested• Doing work in the wrong order• Doing work too slowly

Treatment Errors• Not acknowledging the customer• Not listening to the customer• Not reacting appropriately to the customer

Tangible Errors• Failure to clean facilities• Failure to control noise

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CUSTOMER ERRORSPreparation Errors

• Failure to bring necessary materials to the encounter

• Failure to engage the correct serviceEncounter Errors

• Failure to remember steps in the service process• Failure to follow system flow• Failure to follow instructions

Resolution Errors• Failure to learn from experience• Failure to adjust expectations appropriately

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SEVEN STEPS TO POKA-YOKE ATTAINMENT

Quality Processes

Utilize a team environment

Elimination of Errors

Eliminate the “Root Cause” of The Errors

Do It Right The First Time

Eliminate Non-Value Added Decisions

Implement a Continual Improvement Approach

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POKA-YOKE APPROACH Proactive Approach :

A fully implemented ZERO DEFECT QUALITY system requires Poka-Yoke usage at or before the inspection points during the process.

Poka-yoke will catch the errors before a defective part is manufactured 100% of the time.

Reactive Approach :

Check occurs immediately after the process.

Can be an operator check at the process or successive check at the next process.

Not 100% effective, will not eliminate all defects.

Effective in preventing defects from being passed to next process.

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Two Poka-Yoke System approaches are utilized in manufacturing which lead to successful ZERO DEFECT QUALITY:

1.Control Approach:

Shuts down the process when an error occurs.

Keeps the “suspect” part in place when an operation is incomplete.

2.Warning Approach

Signals the operator to stop the process and correct the problem.

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CONTROL SYSTEMTakes human element out of the equation ; does not

depend on an operator or assembler.

Has a high capability of achieving zero defects.

Machine stops when an irregularity is detected.

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WARNING SYSTEMS

Sometimes an automatic shut off system is not an option.

A warning or alarm system can be used to get an operators attention.

Color coding is also an effective non-automatic option

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TEN TYPES OF HUMAN MISTAKES

ForgetfulnessMis-understandingWrong identificationLack of experienceWillful (ignoring rules or procedure) Inadvertent or sloppinessSlowlinessLack of standardizationSurprise (unexpected machine operation, etc.) Intentional (sabotage)

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POKA-YOKE DEVICESPoka yoke is implemented by using simple objects like

fixtures, jigs, warning devices and the like to prevent people from committing mistakes, even if they try to!.

The main feature of poka-yoke devices is their exceptional suitability for reducing or eliminating defects through effective feedback and instantaneous corrective action.

These devices are capable of being used all the time by all workers; simple and usually installed with low implementation cost.

Poka-yoke devices help eliminate errors and defects by giving machines the “intelligence” to stop and signal when a error occurs.

Poka-yoke devices stop machines and alert workers when a problem exists.

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THE THREE LEVELS OF POKA-YOKE:

There are three levels at which your company can

effect poka-yoke:

Eliminating errors defects and losses at the source

or prevention of a mistake from being committed..

Detection of a loss or mistakes it occurs,allowing

correction before it becomes a problem.

Detection of a loss or mistakes after it has

occurred,just in time before it blows up into a major

issue(least effective).

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EXAMPLES OF POKA-YOKE PRODUCTS

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IMPLEMENTATION IN MANUFACTURING Poka-yoke can be implemented at any step of a

manufacturing process where something can go wrong or an error can be made.

Shigeo Shingo recognized three types of poka-yoke for detecting and preventing errors in a mass production system:

The contact method identifies product defects by testing the product's shape, size, color, or other physical attributes.

The fixed-value (or constant number) method alerts the operator if a certain number of movements are not made.

The motion-step (or sequence) method determines whether the prescribed steps of the process have been followed.April 10, 2023 20

ADVANTAGESThey are simple and cheap.

They are part of the process, implementing what

Shingo calls "100%" inspection.

They are placed close to where the mistakes occur,

providing quick feedback to the workers so that the

mistakes can be corrected.

Once put in place, they require minimal supervision.

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CONCLUSION Poka-yokes deals with understanding

why people make errors and how to analyze the process to know where errors are likely to occur and what root causes contribute to them.

Since the poka-yoke devices detect errors at their roots n prevent them from blowing up to become bigger problems, there is consistency in the quality of the products, saving the cost and time spent in subsequent quality inspection processes.

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THANK YOU

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