Can someone explain the 5 Why method for problem solving and state the difference between 5 Why and Root Cause Analysis?

Is the 5 Why method better for shop floor personnel and operators?

Terry O

quote:

Originally posted by Terrence O'Hanlon:
Can someone explain the 5 Why method for problem solving and state the difference between 5 Why and Root Cause Analysis?

I would say that the '5 Why' method is simply a tool _for_ Root Cause Analysis, not a replacement for it. I'm have kind of a love/hate thing for the 5 Whys, because it can be really frustrating when somebody tries to make you go through the motions. The 5 Whys are one of those things where they work really well if you _want_ them to work, and you tailor your thinking to _make_ them work, but it becomes a 'religious' issue at times, and you can't usually change someone's thinking by bullying them with the 5 Whys.
For instance, something would be broken, and the manager would ask "Why?" and if you're not a proponent of the 5 Whys, and are in poor humour over your broken machine, you might say "Because the gang of monkeys who operate the machine are morons." Now, this stops the 5 Whys in their tracks, because it wasn't the 'right' answer to keep the process going. If you were a proponent of the 5 Whys then the conversation might go more like this:
"What happened?"
"A scrap roll fell in the machine and was crushed against a solenoid and broke it."
"Why did it crush the solenoid?"
"Because nobody pulled it out in time after it fell in."
"Why was it in there?"
"Because the machine can't manipulate small rolls reliably."
"Why can't it handle the small rolls?"
"The spacing of the wheels on the grab carriage are too far apart for small rolls."
"Why do they have to be so far apart?"
"Because if they were close enough together for the small rolls then it wouldn't be able to reliably manipulate the full-size, non-scrap rolls."
"Why are we making scrap rolls?"

And that, there, is the important question and it can start a whole new set of 5 Whys. I'd rather focus on the monkeys who would rather go for a smoke than watch the machine they are paid to watch, but that's just me.

quote:

Is the 5 Why method better for shop floor personnel and operators?

I suspect that it is, simply because it requires no literacy skills, which monkeys don't always possess (I'm still a bit pissy about my solenoid, you see).
The bottom line for me, personally, is that the 5 Whys are a tool than can easily be applied by anyone _WHO_WANTS_THEM_TO_WORK_ and they have a reasonable chance of helping you to get to the root cause of a problem, but they are _not_ a cure-all. At least they don't require 3 months and a 600 page write-up.

Terry,

In Root Cause Failure Analysis we simply do not just ask why but also how can the problem occur.

It is just having a VHS in your home and you rewind your tape, which means that when we do a thorough Root Cause Failure Analysis, we are just doing a sequence of events about what really happen as based from evidences.

Actually 5 whys is a misnomer and it is not actually asking why-why 5 times, most of the time it will be more than 5 why and sometimes less than 5.

If we have a problem then we ask why it happen and come up with the answer which in Root Cause is called hypothesis or propable cause, we need to verify if this is really what happens before we go on to the next why and so on, and sometimes we also need to ask how can the failure or problem happen instead of just asking why several times.

My Warm Regards,

The 5-Why method is one that we adopted at one of my larger clients for the shop floor as a first pass. It is one method for root-cause, but not the only one.

When we put together the best practice, we stole much of the information from the nuclear power industry. Next, we developed a decision tree at the beginning of the 5-why analysis which helped the user identify whether the particular problem merited a 5-why or a more in-depth process. In the body of the 5-why analysis we identified how to handle branch answers and that multiple root-causes may be determined. At the end, we identified how to tell if you actually found a root-cause and how to proceed in follow-up.

If anyone is interested in the document, let me know and I will hunt it up to post here (the draft without the client's material on it - SBD owns the best practice).

Howard

quote:

If anyone is interested in the document, let me know and I will hunt it up to post here (the draft without the client's material on it - SBD owns the best practice).

I, for one, would love to see it.

Terrence,
The 5-Whys is a well established RCA methodology, but it is not much favored by the Gurus of the Root Cause Analysis methodology. Mike points out some of its structural weaknesses. It is a simple technique very suitable for the less complex problems and hence for the shop floor.

Mike:

Here is the sanitized best practice.

In the actual best practice, the first step is to determine if the problem is safety related, has a production value over a certain value or is on equipment over a certain value (as well as a few other requirements of the company). If they exceed the selected requirements, they are shunted over to another, more complex, RCA system which requires corporate engineering.

In my travels, I will use the five why system that I am outlining here as a quick and dirty method to see where things go. For anything of true importance to the client or may impact safety, regulations or reputation (the clients or my own), I will usually default to the PROACT system - my preference.

Following this post, I will put up an article with an example using a repaired Westinghouse PAM motor commissioning-following-repair failure.

Howard

Root_Cause_Analysis_Best_Practice.pdf (72 Kb, 121 downloads)

This is the article.

I sharpened the best practice using the documents cited in the bibliography, which are free to download.

The purpose of the best practice, in the previous post, was to push the concept of RCA down to the floor level.

Howard

Root_Cause_Analysis_for_the_Rest_of_Us.pdf (33 Kb, 114 downloads)