In our last article, we welcomed Joe Weimer as Quality Director at Wiley Metal. We mentioned that Joe has experience with process improvement and root cause analysis. We briefly explained the definition of each. Here, we want to delve a bit deeper into root cause analysis and how to perform a root cause analysis for your metal fabrication product problem.
Defining “Root Cause”
A root cause is the core issue that is the cause of a product anomaly or issue. It is often deeper than it appears at first glance. On a personal level, for example, if you have back pain you can treat the pain with medication. This, however, just masks the pain, it doesn’t address the root cause of it. To get to the root cause you may need x-rays, chiropractic care or even surgery. Until that root cause is determined and addressed, the problem will likely persist.
The same is true in manufacturing metal fabricated products. If a problem occurs it can be tempting to address the surface issue and perhaps even “budget” for a certain amount of waste. It would be more prudent to get to the root cause or causes. That is the purpose of a root cause analysis.
Performing a Root Cause Analysis
In our previous article, we mentioned the four steps in determining a root cause which includes:
- Gathering data about the issue
- Charting causal factors
- Target the root cause or causes
- Creating solutions to root causes
In a root cause analysis, a brainstorming style process is often used, involving those with a potential impact on the production issue. On a whiteboard or flip chart, a Fishbone Diagram can be helpful in charting potential causes. A Fishbone Diagram starts with a horizontal line with the “tail” of the fishbone at the left and the head to the far right. In between, a series of lines extend diagonally to the left both above and below the horizontal line. These serve as the fishbones.
The problem, anomaly or non-conforming issue is written clearly at the head or to the right of the horizontal line. Starting from the head and working towards the tail (left) the diagonal lines will serve as a place to write potential core issues. The group starts by submitting potential causes and then following up with the “whys” an issue is occurring. Each why is followed up by another.
It may sound amusing, but it is kind of like having a five-year-old who keeps asking “why?” no matter what answer is given to him. Here- however, “Because I said so.” is not an acceptable answer.
Each answer is added to the “bones” of the Fishbone Diagram working toward the tail where, in theory, you will be much closer to the root cause. In fact, there is a “5 Whys” theory that suggests “why?” should be asked five times for each potential cause, although 5 isn’t necessarily the perfect number.
Resolve Anomalies by Finding Permanent Solutions
There are multiple approaches to using root cause analysis, but they all in some form or another, encourage manufacturers to look beyond the obvious or patchwork solutions. The goal is to find permanent, solid solutions to improve processes and resolve anomalies once and for all.
A root cause analysis could determine if there is a high rate of defective parts produced on Line A on the shop floor, for example, that an assembly line is moving too quickly, training needs to be improved, higher quality hires need to be made, or that sales are over-promising on deadlines. It could be that a cutting tool needs to be sharpened more frequently or a better cutting tool needs to be found. The list could go on and on. The more deeply you dig, however, there should be an increasing consensus on the root cause and a plan enacted to cure it.
In our third and final article on the subject, we will explore why business process management can help your manufacturing team adapt to an evolving marketplace.