C
Chicoria
I find 5-why very effective. But there is a flaw in using 5-why and it has to do with what "Why" question you ask. You can ask why all day to the last answer you get, and still get nowhere (like an annoying child asking why to anything you say) .
I have found that 5 why works best with two other tools.
1. Having an understanding of how the system should work ideally. If you understand this you will ask questions as to why there was a departure from the ideal.
2. Gathering data between why questions to determine the exact departure from the ideal. I never ask a why question unless it is based on a departure from the ideal.
Example (a real one): A burr was missed at a milling op - found mid process by inspection and resulting in extensive rework. The GM wants the miller fired for causing rework.
Wrong way to use 5-why:
Q. Why did the operator miss the burr?
A. The operator didn't look for it.
Q. Why didn't the operator look?
A. The operator never looks for that burr, It never happened before.
Q. Why didn't it happen before?
A. I don't know.
Q. Why don't you know?
A. If I know that then I would know and I don't know. (This leaves you at a dead end - to continue asking why would be silly.
Better way:
Q. Why did the operator miss the burr?
A. The operator didn't look for it.
(You think: the operator should be looking for it in an ideal situation this is a departure from the ideal. So it is time to get some more data before you ask the next why
Q. Was the operator trained to look for it? (This is a set up for the next why.)
A. No.
Q. (You find the person who trained the operator.) Why wasn't the operator trained to check for that burr?
A. We never had that burr be a problem before.
Q. (get more data) But shouldn't the operator be trained to visual the part? Was that part of the training?
A. Yes, but it's a small burr and the next op is burring and it should have been taken off there where they have better tools.
(You now get more data from Burring)
Q. Why didn't you remove that burr?
A. I never remove that burr, quality has always accepted it.
(Now this is really strange. More data needed. You go see quality. As it turned out a new inspector was on the job and rejected the small burr that had never been rejected before. The normal inspector explains - we don't reject this burr because it goes to shop peen next and that takes the burr off. When it comes back it is in spec.
Q. (You think this would not have happened if it were documented - departure from ideal. So you ask) Was this ever documented?
A. I guess not.
Q. Why didn't you document it?
A. You can't document everything
Q. Did anyone ever train you on documenting with "key points"?
Miller not fired. Training on TWI "key points" Check found this was generally not understood in inspection so general training done. Follow up for next few months to see that key points are being noted by inspection. Key points being added to Op sheets as they come up for use.
At this point it is also a good idea to go back and check to see that each departure from the ideal is fully explained by the root cause you found. Sometimes there are more than one root causes. In this case you might check into what was going on that the burr hand let a burr go without knowing why it was okay.
I have found that 5 why works best with two other tools.
1. Having an understanding of how the system should work ideally. If you understand this you will ask questions as to why there was a departure from the ideal.
2. Gathering data between why questions to determine the exact departure from the ideal. I never ask a why question unless it is based on a departure from the ideal.
Example (a real one): A burr was missed at a milling op - found mid process by inspection and resulting in extensive rework. The GM wants the miller fired for causing rework.
Wrong way to use 5-why:
Q. Why did the operator miss the burr?
A. The operator didn't look for it.
Q. Why didn't the operator look?
A. The operator never looks for that burr, It never happened before.
Q. Why didn't it happen before?
A. I don't know.
Q. Why don't you know?
A. If I know that then I would know and I don't know. (This leaves you at a dead end - to continue asking why would be silly.
Better way:
Q. Why did the operator miss the burr?
A. The operator didn't look for it.
(You think: the operator should be looking for it in an ideal situation this is a departure from the ideal. So it is time to get some more data before you ask the next why
Q. Was the operator trained to look for it? (This is a set up for the next why.)
A. No.
Q. (You find the person who trained the operator.) Why wasn't the operator trained to check for that burr?
A. We never had that burr be a problem before.
Q. (get more data) But shouldn't the operator be trained to visual the part? Was that part of the training?
A. Yes, but it's a small burr and the next op is burring and it should have been taken off there where they have better tools.
(You now get more data from Burring)
Q. Why didn't you remove that burr?
A. I never remove that burr, quality has always accepted it.
(Now this is really strange. More data needed. You go see quality. As it turned out a new inspector was on the job and rejected the small burr that had never been rejected before. The normal inspector explains - we don't reject this burr because it goes to shop peen next and that takes the burr off. When it comes back it is in spec.
Q. (You think this would not have happened if it were documented - departure from ideal. So you ask) Was this ever documented?
A. I guess not.
Q. Why didn't you document it?
A. You can't document everything
Q. Did anyone ever train you on documenting with "key points"?
Miller not fired. Training on TWI "key points" Check found this was generally not understood in inspection so general training done. Follow up for next few months to see that key points are being noted by inspection. Key points being added to Op sheets as they come up for use.
At this point it is also a good idea to go back and check to see that each departure from the ideal is fully explained by the root cause you found. Sometimes there are more than one root causes. In this case you might check into what was going on that the burr hand let a burr go without knowing why it was okay.
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