group 3 poka yoke

8/7/2019 Group 3 Poka Yoke

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PresentationOn

Poka Yoke

Presented by:

Group 3

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A common mistake of people who try to makethingscompletely fool-proof is to underestimate

the ingenuity ofcomplete fools.

-- DouglasAdams

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` Shigeo Shingo invented the Japanese concept calledPoka-Yoke (pronounced POH-kah YOH-kay)

` The term "poka-yoke" comes from the Japanese words"poka" (inadvertent mistake) and "yoke" (prevent).

` Poka-Yoke means to mistake proof the process

The essential idea of poka-yoke is to design yourprocess so that mistakes are impossible or at least

easily detected andcorrected

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Background and istory


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` Apoka-yoke device is any mechanism that eitherprevents a mistake from being made or makes themistake obvious at a glance

` AsShingo writes, "Thecauses of defects lie in workererrors, and defects are the results of neglecting thoseerrors. It follows that mistakes will not turn intodefects if worker errors are discovered and eliminatedbeforehand


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` The main objective of poke yoke is to achieve zero defects

` Poka yoke devices should have the followingcharacteristics: useable by all workers

simple to install

does not requirecontinuous attention from the operator (ideally, it should

work even if the operator is not aware of it)

low-cost

provides instantaneous feedback, prevention, orcorrection

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` Forgetfulness

` Misunderstanding

` Wrong identification

` Lack of experience

` Willful (ignoring rules or procedure)

` Inadvertent or sloppiness

` Slowliness

` Lack of standardization

` Surprise (unexpected machine operation, etc.)

` Intentional (sabotage)

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` Poka-yoke devices fall into two majorcategories:

Prevention

Detection

` A prevention device engineers the process so that it isimpossible to make a mistake at all

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Example of Prevention Category

3.5 inch diskettecannot be inserted unless diskette is orientedcorrectly. Thisis as far as a disk can be inserted upside-down. The beveledcorner of the

diskette pushes a stop in the disk drive out of the way allowing the diskette

to be inserted. This feature, along with the fact that the diskette is not

square, prohibit incorre

ct orientation. 10


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` A detection device signals the user when a

mistake has been made, so that the user can

quickly

corre

ct the problem

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Detection Category


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Incorrect Correct

Example 1

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All internal lever are not

positioned properly so theother lever cannot be

locked.

All internal lever are

positioned properly so

outer lever can be

locked.

Example 2

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Example 3

Incorrect Correct

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Example 4

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Error: putting a tube into a

patients stomach which was

intended for their lungs.

Example 5

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Graphical user interfaces are all about mistake proofing. Remember

the DOS error message: Bad Command or File Name? It can't

happen when you point and click from a list.

Example 6

DOS- Character User Interface Windows - Graphical User Interface

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Example 7Overlapping doors are used as

firedoors. The problem is that they

can be closed incorrectly.

This lovely mistake proofing device from

Wales solved the problem...

By proping the outter door open enough to

allow the inner door to swing past

before closing completely. You cannot close

the door wrongly.

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Example 8This airport luggage cart has

brakes which are applied

whenever the yellow handle isnot depressed. Carts will not roll

unless they are attended. When

carts nested, the rear wheels of

all but the lastcart are wedgedoff the floor, so thecartscan be

pushed easily by airport staff

returning them to service areas.

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Automatic light switch

in kids' bathroom

turns light on

automatically. Afterthe bathroom has

been unoccupied for

a few minutes, the

light goes off

automatically. The

error of forgetting toturn off the light is

eliminated.

Example 9

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Stove A

Stove B

In A it is difficult to tell

which knob turns on

which burner?

B is Right. Because there is a natural

one-to-one mapping. Here the point is

that a little attention to detail, not a big

change, can make a huge impact onour ability to use the system

Example 10

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Whose signature is required?

Before:

After:

Example 11 (I)

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Here is an example of a form.

Before: We have all of these people who are supposed to

sign the engineering change notice and one really have to

thinkcarefully about who have to sign it.

After: We have a grid. The grid now says what type of

changes occurred, and has blanked out the unnecessary

signatures. So, now the form actually walks you through theapproval process so that youcan determine how to get the job

done.

Example 11 (II)

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` Eliminate unnecessary or duplicate steps

Use flow charts to visualize the process

` Keep it simple

You dont have to spend a lot of money

` Use many Poka-Yoke devices in a process

There isnt a quota on how many you can use

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` Poka-Yoke means to mistake proof the process

Remove the opportunity for error

x Improve the process

x Make wrong actions more difficult

If you cant remove the opportunity for error

x Make it easier to discover the errors that do occur

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