pokayoke final

8/8/2019 PokaYoke Final

1/25

MISTAKE-PROOFING(POKA-YOKE)

Presented To: Prof. Raj Mukundan

Group Number- 12


2/25

Poka Yoke

Poka means Mistakes & Yoke means Avoid. Its objective is

to achieve Zero Defects.

Poka-yoke is a quality assurance technique ,the aim of poka-yokeis to eliminate defects in a product by preventing or correctingmistakes as early as possible.

Term adopted by Dr. Shigeo Shingo as part of the ToyotaProduction System in 1960.

It was originally described as baka-yoke, but this name mean

Fool-Proofing so the name was changed to the Poka-yoke.


3/25

DEFECTS AND ITS IMPACT

Defect free product is a necessity to compete in themarket place.

Every Customers has a right to demand 100% goodproduct /service and every provider has an obligation toprovide the same.

Bad products hurt both reputation and bottom line(Scrap, rework, warranty.etc.,.)

Defects have a direct impact on process yield affectingspeed and flow of the product to the customer.


4/25

Typical Errors

Processing errors

Missing Operation

Inappropriateprocedures

Missing parts

Missing information

Wrong parts

Damaged materials

Tools or equipmentimproperly preparedor setup

Human Errors


5/25

HOW TO USE MISTAKE PROOFING?HOW TO USE MISTAKE PROOFING?

Identify the process.

Process can fail

Decide right poke yoke approach

Use of checklist

Trail the method

Train the operator


6/25

PRINCIPLES OF POKA YOKE


7/25

Why is Zero Defects anImportant Concept?

Maintain Customer Satisfaction & Loyalty Happy Customers mean more sales!

COSTS

There is always a costassociated with

manufacturing defects!


8/25


9/25

SOME MISTAKE-PROOFING STRATEGIES

Make it harder to create the error

Make it possible to reverse the error

Make it obvious that the error has occurred

Detect deviations from procedures or fixed values (e.g.,Number of parts)

Design:

Design process so it tolerates the error and doesnt result in adefect

Design process to decrease complexity


10/25

APPROACHES TO MISTAKE PROOFING

Control approach

Shuts down the process when an error occurs

High capability of achieving zero defects (ie robust design that cantolerate variation or eliminates variation or assembly mistakes)

Warning approach

Signals the operator to stop the process and correct problem orcheck for a problem (ie are parts still ok, is oil level ok)

Sometimes an automatic shutoff is not an option

Dials, lights, and sounds to bring attention to the problem


11/25

Mistake Proofing Devices

Types of mistake proofing devices within control or warning approach can be of:

Contact type:

The contact type makes contact with every product or has a physical shapethat inhibits mistakes.

Example: Fixed diameter hole through which all products must fall andan oversize product does not fall through and a defect is registered.

Fixed value type:

The fixed value method is a design that makes it clear when a part is missingor not used.

Example: Egg tray used for supply of parts,

Motion step type:

The motion step type automatically ensures that the correct number of stepshave been taken.

Example: An operator is required to step on a foot pedal every assemblycycle, Correct sequence for switches that do not work unless the order iscorrect.


12/25

EXAMPLES OF SOME USEFUL MISTAKE-PROOFING DEVICES

Guide pins, to assure that parts can onlybe assembled in the correct way.

Limit switches, that sense the presence orabsence of a part.

Mistake-proofing jigs, detect defects

immediately upstream of the processensuring that only the correct part reachthe process.

Counters, that verify that the correct

number of parts or steps have beentaken.

Checklist, that reminds operators to docertain actions.


13/25

Summary of Mistake Proofing Types

Control Warning

Contact Parking height bars Shopentrance bell

Fixed Value French fry scoop Trays withindentation

Motion Step Foot pedal operated Machine Beepers onATM


14/25

EVERYDAY EXAMPLES OF MISTAKE PROOFING

Home

Automated shut-offs on electric coffee pots

Child-Proof caps on mediations

Ground fault circuit breakers for bathrooms or outside electric circuits

Office

Spell check in word processing

Question prompt Do you want to delete? after pressing the Deletebutton on your computer.

Factory:

Dual palm button and light curtains on machines

Retail:

Tamper-Proof packaging

Bar coding at checkout.

I have an

extra part.

I must

have

omitted a

step!


15/25

CONTROL APPROACH

Automobile controlshave a mistake-

proofing device toinsure that the key is

in the on positionbefore allowing thedriver to shift out of

park. The keyscannot be removed

until the car is in

park.

Electronic door locks can have threemistake-proofing devices: Insures that no door is leftunlocked. Doors automatically lock when the

carexceeds 18 miles an hour.

Lock won't operate when door isopen andthe engine is running.


16/25

Manhole covers are round because if theywere of any other shape (Ex: Square) itwould be possible to accidentally drop onethrough the hole while removing it.

CONTROL APPROACH


17/25

WARNING APPROACH

Warning lights alert the driver of potentialproblems. These devices employ a warning

method instead of a control method.(Seatbelts, High engine temperature, Low oil

pressure)


18/25

TYPES OF SENSING DEVICES

Sensing devices that are traditionally used inpoka-yoke systems can be divided into threecategories:

1. Physical contact devices

2. Energy sensing devices

3. Warning Sensors

Each category of sensorsincludes a broad range ofdevices that can be useddepending on the process.


19/25

PHYSICAL CONTACT SENSORS

These devices work by

physically touchingsomething.

This can be a machine partor an actual piece beingmanufactured.

In most cases these devicessend an electronic signal

when they are touched.

Depending on the process,this signal can shut downthe operation or give an

operator a warning signal.


20/25

TOUCH SWITCH

Used to physically detect the presence or absenceof an object or item-prevents missing parts.

Used to physically detect the height of a part ordimension.


21/25

ENERGY SENSORS

These deviceswork by usingenergy to

detect whetheror not an defecthas occurred.

Fiber optic

PhotoelectricVibration


22/25

WARNING SENSORS

Warning sensorssignal the operatorthat there is aproblem.

These sensors usecolors, alarms, lightsto get the workersattention !

These sensors maybe used inconjunction with acontact or energy

sensor to get the

Lights connected

to Micro switches

& timers

Color Code

Lights

Th S G id li t P k Y k Att i t


23/25

The Seven Guidelines to Poka- Yoke Attainment

1.) Quality Processes - Design Robust quality processes toachieve zero defects.

2.) Utilize a Team Environment- leverage the teamsknowledge,experience to enhance the improvement efforts.

3.) Elimination of Errors -Utilize a robust problem solvingmethodology to drive defects towards zero.

4.) Eliminate the Root Cause of The Errors

5.) Do It Right The First Time- Utilizing resources to performfunctions correctly the first time.

6.) Eliminate Non-Value Added Decisions- Dont makeexcuses-just do it

7.) Implement an Incremental Continual ImprovementApproach-implement improvement actions immediately andfocus on incremental improvements; efforts do not have toresult in a 100% improvement immediately.


24/25

SET A STANDARD

Errors are not acceptable

Use cross-functional teams to design and maintainprocesses to be robust

Make it right the first time

Good: Design products and processes so that we make it right thefirst time

Best: Design products and processes so we CANT make it wrongany time and get a concurrent productivity improvement


25/25

pokayoke final

Documents