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Definition Error-Proofing vs. Mistake-Proofing - Differences

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David McGan

#1
I freqently see the terms "error-proofing" and "mistake-proofing" used in various contexts, with what I perceive as interchangeable definitions.

I know there are various degrees of "error/mistake" proofing (i.e. prevent from being made vs automatic detection if made / prevent from being moved to the next operation, etc).

My question is: Is there any real difference between the terms or should I assume that either can be used to connote the same concept?

While this might on the surface seem "much ado about nothing," serious discussions have arisen in the past over what is the appropriate terminology.
 

Jim Wynne

Super Moderator
#3
jmp4429 said:
I’m pretty sure the two are interchangeable terms for exactly the same thing. However, I would not consider detection of the defect to be true “error proofing.” Error proofing should prevent the error in the first place.
I agree; the terms are interchangeable, but automated inspection isn't error-proofing. An argument could be made, though, for some sort of thing that prevents further processing of defective material. The error being prevented isn't the defect iteself, but adding value to defective material.
 
C

Craig H.

#4
Jim Wynne said:
I agree; the terms are interchangeable, but automated inspection isn't error-proofing. An argument could be made, though, for some sort of thing that prevents further processing of defective material. The error being prevented isn't the defect iteself, but adding value to defective material.

Jim, I'd have to say that I agree that MAYBE an argument could be made that inspection is error proofing, but I will gladly provide the other side to that argument. Semantics, I guess, but if the mistake can be prevented, it is much better than to have a wiz-bang inspection doohickey to spit the bad product out.

JMHO
 

Miner

Forum Moderator
Staff member
Admin
#5
Shigeo Shingo, who popularized the methods, made the following distinction:

Mistake-proofing - done to the PROCESS to prevent mistakes from occurring, stop the error from further processing, warn that the error has occurred, etc.

Error-proofing - done to the DESIGN to prevent assembly errors. Examples include adding design features to prevent upside-down, backwards or reversed assembly; using snap-together features to eliminate fasteners (eliminating missing, incorrect, high/low torque).

However, most people using the terms do not know this distinction and do use them interchangeably.
 

Jim Wynne

Super Moderator
#6
Craig H. said:
Jim, I'd have to say that I agree that MAYBE an argument could be made that inspection is error proofing, but I will gladly provide the other side to that argument. Semantics, I guess, but if the mistake can be prevented, it is much better than to have a wiz-bang inspection doohickey to spit the bad product out.

JMHO
I don't disagree, Craig. Prevention is better. But I think that if you're dealing with a specific human error, and the process has been optimized (i.e., it's making product as well as can be expected) then use of a device that prevents further processing (or shipment) of defectives might reasonably be referred to as error-proofing.
 
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