Asking why to find the real answers to production problems
Brad Cairns is the senior principal at The Center for Lean Learning as well as running a woodworking business called Best Damn Doors in St. Thomas, Ontario, Canada, where he puts lean thinking into action every day. You can reach Brad at 519-494-2883 or [email protected].
I don’t think it’s possible to be responsible for any business department or work cell and not have the question “why” come up at least a few times a day.  
Why did that machine break?
Why won’t people listen to me?
Why aren’t we making more?
Why do we get so many defects?
That list could go on forever. You’re likely reading this and several of your WHY questions are popping to mind.
Manufacturing is probably the wildest roller coaster I’ve ever been on. It’s one of the most complex environments I can think of. 
You’re responsible for procuring raw goods, transforming them into the finished product through many processes, which all have to go right and be sequenced properly. 
Then you’re finished goods often must be transported and coordinated with another group of skilled people to install them to the exact specifications of your discerning customers. 
Compare that to a strict buy-sell model, in which you buy a product already made, and when you sell it, you buy more. Naturally I probably oversimplified that business, but I think you get my drift.
It’s no wonder that every manufacturing day brings a barrage of new problems throughout the entire organization. I’ve yet to talk to any manufacturer who said, “Yeah, last week was perfect. Absolutely nothing went wrong.”

Plenty of problems to solve

I think we can all agree manufacturing provides us the joy of an uninterrupted stream of problems to solve. Let’s first visit the word “problem.” 
I believe we use this word too haphazardly because we all know there’s the thing that you’re facing and below the surface, there’s the core problem. Therefore, I’d like to use some different verbiage, and the initial problem should be more accurately described as an “undesirable effect” of the yet to be discovered core problem. 
When we run around saying this is a problem and that is a problem, I believe we are doing ourselves a significant disservice because that phrasing alone suggests if we solve the thing we are talking about, the issue will be gone. However, if we have not addressed the core problem, then it won’t be very long before another undesirable effect arises.
Fortunately for us, some manufacturing greats who came before us have created powerful and simple tools to help us solve these problems. A lot of the time, I think we don’t solve our core problems because the process of doing so seems too simple. Remember lean thinking is just that, simple. I love the saying, “Smart people can’t believe it’s this simple.”

Asking why five times

When you want to know why something is going wrong, and you know you’re just dealing with an undesirable effect, you just need to keep asking why. Popularized by Toyota in their early days, the Five Why analysis seems simple, yet it is staggeringly effective.
Now I said, “seems simple.” That’s because as you work through the first two or three why’s, even a child could do it. 
However, the closer you get to the core problem the more difficult answering why gets. I promise, by the time you get to the fourth or fifth why, it will require all your brain power to answer the question. Let’s face it, if it were easy, you would’ve already solved the problem.
Here is a popular example of a Five Why from Taiichi Ohno, founder of the Toyota Production System. Ohno, who created the Five Why technique, used this example to teach this method:
“Why did the robot stop?”
The circuit has overloaded, causing a fuse to blow. 
Why is the circuit overloaded?”
There was insufficient lubrication on the bearings, so they locked up.
“Why was there insufficient lubrication on the bearings?”
The oil pump on the robot is not circulating sufficient oil. 
“Why is the pump not circulating sufficient oil?”
The pump intake is clogged with metal shavings. 
“Why is the intake clogged with metal shavings?”
Because there is no filter on the pump.
In the above example, most people would be treating the symptom, likely because it would seem easier and faster to replace the fuse. We tend to do the Five Why method only when we are forced to. The fuse would have just blown again due to the bearings, but I’d bet my bottom dollar most of us would have changed the bearings and fired up the machine again. If the failure happened monthly, we might even start to stock the bearing in our maintenance department. 
But as Ohno demonstrates, the real solution was still deeper. And the wonderful irony is the root cause fix was much more cost effective than repeatedly replacing bearings!

Three Five Why pitfalls to avoid

1.) A major sticking point of an effective Five Why analysis is that there is no “right” answers. There is only your intuition to guide you. When I facilitate a Five Why analysis, after each why, I read the problem statement and the answer out loud and ask one simple question: “Do I believe this to be true?” Then, if it seems true, I follow up with: “If we do this one thing, will the defect be gone forever and never happen again?” Most of the time, you find yourself admitting that probably you should keep digging just a bit further. 
2.) Often you will find there are a few possible answers to choose from. Don’t get stopped because of a fork in the road. Go down one until you either find the root cause or a dead end. Then go back and go down the other. You may even find they are both plausible, in which case I would revert back to whichever one I can do right now, for free (or cheap).
3.) Follow up. All too often no one is actually in charge of finding out if the solution you put in place actually worked, and to what extent. 
Is the project case closed and it’s time to celebrate, or does it need to be revisited with a possible second run-through due to new information or insights? 
If we could train all our people to ask the Five Why’s each time they encounter a problem, our laundry list of daily issues would see a significant reduction and allow us to get back to focusing on what matters: our customers! 

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About the author
Brad Cairns | President/Owner/C-Level

Brad Cairns is the senior principal at Quantum Lean and is dedicated to improving the woodworking industry in North America using lean methods. He also owns Best Damn Doors, a cabinet door manufacturing business in St. Thomas, Ontario. You can reach Brad at 519-494-2883 or [email protected].