Mistake proofing

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Mistake proofing

Mistake proofing is a scientific technique for improvement of operating systems including materials, machines and methods with an aim of preventing problems due to human error. The term “error” means a sporadic deviation from standard procedures resulting from loss of memory, perception or motion.

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Finger print ID lock is an excellent example of mistake proofing. There's no need to fumble for your keys in the dark any more. The Fingerprint ID Door Lock is a cylindrical lock combined with a security bolt that will let you into the house using just your finger. It reads your unique fingerprint and only allows entry to prints it recognizes.

Examples of mistake proofing

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Examples of mistake proofing

Gas pumps are equipped with hose couplings that break away and quickly shutoff the flow of gasoline.

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Examples of mistake proofing

The bathyscaph is a deep water submarine used to explore the very lowest parts of the ocean.It is electrically powered.Once at the bottom,if the batteries or electrical system fail the best outcome would be for the submarine to return to the surface.The designers made this outcome occur by holding the ballast in place with electromagnets.When power is lost,the ballast drops off automatically and sub starts it ascent.

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Examples of mistake proofing

Automobiles controls have a mistake proofing device to ensure that the key in the on position before allowing the driver to shift out of park.The keys can not be removed until the car is in park.

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Examples of mistake proofing

3.5 inch diskette can not be inserted unless diskette is oriented correctly.This is as far as diskette can be inserted upside-down.

The beveled corner of the diskette pushes a stop in the disk drive out of the way allowing diskette to be inserted.This feature,along with the fact that the diskette is not square,prohibit incorrect orientation.

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Examples of mistake proofing

Electronic car locks can have three mistake proofing devices:

• Ensures that no door is left unlocked.

• Door automatically locks when car exceeds the speed of 18mile an hour.

• Lock won’t operate when door is open and engine is running.

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Examples of mistake proofing

New lawn mowers are required to have a safety bar on the handle that must be pulled back in order to start the engine.If you let go of the safety bar,the mowers blade stops in 3 seconds or less.This is an adaptation of the”dead man switch” from railroad locomotives.

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Examples of mistake proofing

Retail stores use electronic article surveillance to ensure that no one walks away without making payment.

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Defect Vs errors

It is important to understand that defects and errors are not the same thing. A defect is the result of an error, or an error is the cause of defects as explained below.

ErrorError DefectDefect

Cause Result

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Prevention of defects

Machineor

human error

Machineor

human errorDetect errorDetect error

Take corrective

action

Take corrective

action

zerodefectzero

defect

Analyze for preventive

action

Analyze for preventive

action

Cause Intermediate result End result

Modify workprocedure to

prevent such errors

Modify workprocedure to

prevent such errors

WorkProcedure

WorkProcedure

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Types of error

• Error in memory of PLAN : Error of forgetting the sequence/ contents operations required or restricted in standard procedures.

• Error in memory of EXECUTION : Errors of forgetting the sequence/contents of operations having been finished.

• Error in PERCEPTION of type : Error of selecting the wrong object in type or quantity.

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Types of error

• Error in perception of MOVEMENT : Error of misunderstanding/misjudging the shape, position, direction or other characteristics of the objects.

• Error in motion of HOLDING : Error in failing to hold objects.

• Error in motion of CHANGING : Errors of failing to change the shape , position , direction , or other characteristics of object according to the standard.

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Human error provoking situations

• Complex design• Inadequate written standards• Too many parts• Mix up• Too many steps• Specifications or critical

conditions• Too many adjustments• Frequent repetition

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