May 27, 2020 Doug Koehler
The Importance of Root-Cause Analysis
Every day we encounter problems in our daily lives, from leaky faucets at home, to assembly components at work that don’t fit. What do they all have in common? There is always a root cause as to why they occurred. The leaky faucet may be from a 30-year-old O-ring that’s no longer soft enough to work correctly. Or if it’s a two-week-old faucet, it may have been a handyman who used a wrench that was too big and destroyed the threads.
Sometimes the root cause of a problem seems obvious, when in reality it’s not. When the wrong bolt is ordered for a new assembly, the cause might be linked to the buyer ordering the part who is less experienced in their job. When the buyer then learns that the bolt they ordered doesn’t fit, they’ll make sure the correct bolt is ordered the next time. End of problem. But what happens when the same wrong bolt gets ordered multiple times by different buyers? Maybe the root cause is not the buyers ordering the parts, maybe there’s something else wrong hidden within the process.
Often the way we structure our processes leads to a higher potential for error. When we verify the process and methods used, we can help to eliminate opportunities for error. In the example above, since multiple people have now made the same mistake, it looks like our original assumption for the root cause may have been a mistake. We may have treated the symptom of the problem, but we never did a root-cause analysis to find the true origin of the issue. This causes the issue to quickly resurface and the error is repeated, costing us more precious time, money and frustration.
To obtain the true benefit of root-cause analysis, the time and resources need to be applied to truly determine the point of origin of the events that created the problem. Let’s go back to those wrong bolts that keep getting ordered. When the cross-functional team gets together, they brainstorm where the error could be coming from. As they step through the ordering process together, it’s discovered on the drawing that there isn’t a part number for the bolt. Only a description: “1/2” x 4” Grade 8 Bolt.” The buyers had been ordering “1/2”-13 x 4” Grade 8” bolts most of the time; unfortunately, the bolts needed to have fine threads (1/2”-20) not the standard course threads (1/2”-13).
So, what might have been the potential root cause for this problem? Additional analysis, testing and verification would have to occur for us to be certain, but based on the information gathered so far, the details required to order the correct part every time were not put on the drawing. An incomplete description and the lack of the correct part number might have been the root cause to why the wrong 1/2” bolts were being ordered.
The fictitious problem described above was rather simplistic, but if you’re on the production floor dealing with the wrong bolts every other day, it can be a troubling, costly problem. There are many tools and methods that can be used to help find the root cause of a problem; the brainstorming method above is one of those techniques. A few of the more structured methods are the application of 5 Whys, change analysis, barrier analysis, Ishikawa diagrams (fishbone diagram), scatter diagrams and Pareto charts.
If you solve the problem without finding the root cause, you may not be solving the real problem. Are you just treating the symptoms? Or are you eliminating the true source of the problem by using root-cause analysis? I encourage you to investigate these simple yet powerful tools to enable your team to find and resolve the true source of your problems.