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Our Production Manager, John, is heading out to the production floor. He sees that his highest priority line is down again. “What is it this time?” he asks. His top mechanic replies, “I can’t believe we are down for a conveyor. We’ll be back up before long, if we have the right sprocket.”
John decides to do a 5 Why analysis even though this appears to be a simple fix. In the old days they might have been satisfied with replacing the sprocket. Today, John wants to make sure that the replacement does not fail prematurely. He wants to address the root cause.
We have already looked at simple 5 Why’s. Several readers commented that many real life examples are not that simple and do not have straight-line answers. Today we’ll look at a complex, multiple path 5 Why.
Complex 5 Why Root Cause Analysis
You will still go through the same basic 7 Steps of an Effective 5 Why as addressed in a previous post. The difference with the Multiple Path 5 Why is that there will be more than one answer to some or all of the why’s. My suggestion is that you only include the answers that you believe are contributing to the issue. The 5 Why can spin out of control and become too complex if you include every conceivable possibility. If you are unsure, you can capture the idea and verify if the condition exists. For example, if someone says, “maybe the bearings have not been properly lubricated.” Capture the idea and verify the condition of the bearing. If the bearing hasn’t been lubricated properly, include it in your Root Cause Analysis. There are situations where you may want to include all options which we’ll discuss next time. Today, we will only include the conditions that we believe exist. Let’s look at the sprocket and do a thorough Root Cause Analysis (RCA):
Problem Statement: Conveyor stops due to a broken sprocket
5 Why – Sprocket Failure
Why #1: Why did the sprocket break?
Answer: [a] excessive stress [b] wrong sprocket
Why 2a: Why is there excessive stress?
Answer: [1] dirty conveyor [2] worn bearings [3] line speed exceeds conveyor design
Why 2b: Why is the wrong sprocket on the conveyor?
Answer: Correct sprocket was not in stock when replaced last time.
Root Causes & Countermeasures
Why 3a [1]: Why is the conveyor dirty?
Answer: Not on cleaning schedule
Why 3a [2]: Why are there worn bearings?
Answer: Bearings have not been PM’d
Why 3a [3]: Why isn’t the conveyor designed for the actual line speed?
Answer: Conveyor was taken from the bone yard to finish an in-house line modification
Why 3b: Why wasn’t the right sprocket in stock?
Answer: Inaccurate inventory
Why 4a [1]: Why isn’t the conveyor on the cleaning schedule?
Answer: New conveyor was not added to the cleaning schedule
Why 4a [2]: Why haven’t the bearings been PM’d?
Answer: Mechanic didn’t know about these bearings
Why 4a [3]: Why was the conveyor taken from the bone yard?
Answer: Management/Engineering decision to manage the cost of the project
Why 4b: Why wasn’t the inventory accurate?
Answer: [1] parts usage is not consistently documented [2] parts inventory is overdue
Why 5a [1]: Why weren’t the new conveyors added to the cleaning schedule
Answer: Early management failure
Countermeasure: Add sanitation requirements to the project management checklist. Update the sanitation schedule to reflect the new conveyor.
Why 5a [2]: Why didn’t the mechanic know about the bearings?
Answer: [2.1] New mechanic that is unfamiliar with the line changes [2.2] Conveyor section pulled from the bone yard was not added to the PM system
Why 6a [2.1] Why wasn’t the new mechanic familiar?
Answer: See 5a [2.2]
Why 6a [2.2]: Why wasn’t this section of conveyor added to the PM system?
Answer: PM’s had already been updated when the decision was made to use conveyor from the bone yard.
Countermeasure: Modify the post project review procedure. Changes to reflect the need for full analysis of the impact of project changes on Safety, Sanitation, PM’s, etc. Update the PM’s to include the new conveyor.
Why 5b [1]: Why isn’t parts usage documented properly?
Answer: No system when the parts clerk is not on site.
Countermeasure: Implement parts usage form to be used on all shifts. Order sprockets as needed to re-establish minimum quantities.
Why 5b [2]: Why is the parts inventory overdue?
Answer: Overtime production prevented completing as scheduled.
Countermeasure: Schedule parts inventory as soon as possible.
John and his team have invested much more time performing a thorough RCA than if they had just replaced the sprocket. You can see though that the team has been able to identify several root causes that need to be addressed. What would happen if they did not address these root causes? They would likely have another premature sprocket failure. This premature failure would be the result of the same conditions that led to the first failure.
The great John Wooden said, “If you don’t have time to do it right, when will you have time to do it over?” If you don’t have the time to address the root causes now, you will likely be dealing with the same issues again. What issue is your plant facing today that warrants a good 5 Why Root Cause Analysis?
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Lean Leadership 
WOW! – How can one not be amazed by just the shear value of these approaches? I think one approach would be to connect the the answers near the end. How can one solution solve many of the root problems. For instance, engineering/management decision to cut costs. If the managers decided to put quality first, that would have created a differernt outcome for a few of the multiple paths. I hope I am getting it 🙂
Christian, always informative.
I’m always amazed at the solutions you present. I think companies would benefit tremendously from implementing your suggestions.
Isaac,
Thanks for your comments. You are right about connecting the root causes. I have seen situations where one countermeasure will resolve more than one root cause. It’s still important to identify all the root causes if you want to prevent recurrence.
Chris
Great post, Christian.
Seems similar to the failure mode analysis one might perform on a component, but expanded to a system level. I implemented a similar, but less formal approach once, as an adjunct to our predictive maintenance program. It works very well, when followed.
One method I used was to consider the identification of the root problem to be the main issue, with the corrective maintenance being considered secondary (in terms of paperwork only).
It also really helped us to properly identify some costs that can easily creep out of control via our job cost analysis. We radically reduced our spares inventory, while reducing downtime and MTBF. I rebelled a bit, at first, at the additional admin burden, but it paid off, big time!
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The following comment was left by Wagner Santos on LinkedIn (TPM Group):
This article is very good. Congratulations!
I see that we still have great difficulty in applying the 5 Why’s, even in the simplest formats.
Thank you.
The diagram of the complex 5Y root cause, resembles the 5 Why analysis that are done in my facility. That is the approach that decided to take, I was able to visit a Toyota Dist. center early in the year. It was a team lead that led me through the bracketed 5 Why, I adopted it immediately. I had inherently wanted to take this initial stance, but after doing some research and seeing the simple, linear 5 why I thought I was doing it wrong. That is where my initial thought to the previous article stemmed from, I didn’t want other people to fall into the same pitfall that I had, with trying to apply a linear 5Y to a complex problem. This article is good, it more closely resembles what I see day to day.
Thank you, Daniel. I appreciate your insight. Most real life events have multiple root causes. Your trip to the Toyota DC must have been quite a treat. I had the pleasure of going to the Subaru plant in Lafayette, IN a few years ago. They are deep into Lean & TPM. It was amazing.
Thanks again,
Chris
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Posted in a LinkedIn group discussion by Wagner Santos:
This article is very good. Congratulations!
I see that we still have great difficulty in applying the 5 Why’s, even in the simplest formats.
Thank you.
Posted in a LinkedIn group discussion by Paolo Defazio •
Hi christian,
good article. Anyway, I would suggest an application of 4M tools ( fishbone analysis) before 5 whys. In my experience I use 4M to explore “horizontally” a problem. In this way I find all root causes. The I use 5 whys to approach “vertically” each root cause. If u cross these two tools in this way your problem solving capacity grows up.
Posted in a LinedIn group discussion by Andy Maclellan •
Great article Christian and I can agree with Paolo’s idea of using the Ishiwaka diagram as a supporting visual methodology to the 5 Ws . The way that you suggest using the 5ws is excellent for helping to drill down towards the true causes – then you need to be capable and experienced to identify and prioritise the solution(‘s). Keep up the good work and continue to stimulate your audience !
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Hi Christian,
Exellent article and method. If I may add to this, I have found by thinking outside the box so to speak, allows smarter list reduction especially on complex.
The people issue’s are usually presented in a defensive mode due to fear of reprisal.
The question of why, is better presented as “what do you feel were the issues which led to this failure & why. This helps to reduce anxiety and builds trust which often opens the door & gets you to the real issues by the 3rd “Why”.
Material variation & its contribution is often not realised, without understanding the specification, manufacturing capabilities and standard deviation / distribution, the “Why” does not indicate or highlight out of control processes.
SOP’s v OEM recommended operation practice varience’s are often clear violations from the recommended standards / best practice and readily supported by senior management. On top of this, individual preferences come into play which makes a mockery of best practice if not tightly controlled via high standards set and enforced.
I think you get the drift, contemplating evasive comments, poor training and control to specification often underly the real root cause, 5 “Why” should be used to get you into the target area, but to hit bulls-eye you require out of the box thinking to obtain true root cause.
Hi Derek,
Defensiveness is definitely and obstacle to overcome when seeking the root causes or to improve any process. Learning to help others let their guard down is another skill set needed to lead in a Continuos Improvement environment and even more critical when trying to establish a CI culture. Thanks for your insight.
Chris
Mr. Christian,
Thanks for the post. It’s really helpful. For the first time I am reading about the complex method. It’s really a very good job. I am going to start the practice asap.
Thank you again.
Stay Well.
Rana
Rana,
Thank you for reading this blog and for your kind feedback. I hope that these posts are helpful for you. Feel free to ask questions if I can help along the way.
Chris
Great article. I just came across it. This is similar to “Cause Mapping” tool what I have utilized and has been explained by ThinkReliability in this brief 30 minute long YouTube video.
Please take a look at it and provide your comments/questions and suggestions.
http://m.youtube.com/watch?v=12kco9UzwGE&desktop_uri=/watch?v%3D12kco9UzwGE
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