The Fishbone Diagram. One of the most versatile tools in the Lean toolbox. It can be summed up as a tool for facilitating a root-cause brainstorming session. Effectively facilitated, a problem-solving session using a Fishbone Diagram (also called the Ishikawa Diagram), can uncover unimaginable realities about your business or production process. It can be argued that this tool (along with other Root Cause Analysis tools such as 5-Why) is the cornerstone of any Lean Manufacturing implementation. What makes this tool so powerful though? And why is its use so widespread? Below I’ve outlined some of the ingredients in the secret sauce of the Fishbone Diagram’s power. If you’re not already applying this tool in your business, you’re already falling behind!
1) Simplicity. Simply stated: simplicity is genius. The learning curve for a Fishbone Diagram itself is literally 5 minutes. It may take a lot more time to learn to be an effective facilitator; but given a strong background in facilitation, this is an easy plug-and-play tool. The key components are: a list of potential sources of problems (usually 4 to 6 items), a well defined problem statement, space to write ideas where everyone in the group can see, and a follow up action list. You’ll also need some process for prioritizing which “potential causes” will be investigated and in what order. The process itself doesn’t fully “solve” the problem; it just gives you a list of likely suspects which is a great place to start. The problem is only truly solved through rigorous trial, observation, adjusting -> wash, rinse, and repeat until you get the result you want. The beauty of simplicity is versatility. I’m convinced that this process can be applied to any problem big or small from machine downtime to world hunger (which, depending on what industry you’re in, could be very related problems).
2) Team Calibration. One of the most impressive things I always get out of Fisbhone sessions is the multitude of issues that different people believe are causing the problem. It seems that the root of the problem in people’s minds depends highly upon your personal perspective, which is shaped by your position in the organization. Furthermore, people often believe the problem is being created by something outside of their immediate control. During these sessions, what is usually discovered is that everyone has some role in what I call “feeding the monster”. Everyone has some behavior/action that is immediately causing or could have taken to fix or avoid the problem. One of the keys to a great Fishbone session is having a cross-functional group of people who are close to the process attend and engage in the session. This might be line operators, mechanics, QA technicians, supervisors, training and admin personnel, and others who support the business system. You also need to create an environment where people are free to contribute ideas without judgement or fear of retribution. Then you need to prioritize, as a team, the most likely root causes that will be acted upon, in which order, by who, and by when. This makes the action list manageable and helps to capture the biggest bangs in improvement up front. This also helps everyone involved to see the problem the same way and decide collectively what exactly will be done about it. The key is to understand that in almost all cases, there are several contributing conditions and triggers that result in a problem. The goal is to eliminate the possibility for that specific problem to reoccur. Then jump to the next problem and eliminate it as well. This is the process of continuous improvement.
3) Unintended overall process improvement. As you fix issues identified during one Fishbone session, you’ll start to see symptoms all over the plant go away, leading to organization-wide process improvement. Case in point: One of the issues that repeatedly showed up in Fishbone sessions with a prior client was that the operator was not fully certified before being released to work independently on the line. Under further investigation, several gaps were identified in the organization’s training execution. We were able to close several gaps in the training program, which contributed to a significant increase in plant-wide efficiency in just one quarter of the year. In essence, just doing the Fishbone analysis on one small part of the manufacturing process led to significant improvement in overall process efficiency and employee morale. This is the beauty of getting to the root of an issue – that same root is usually responsible for multiple weeds. Finally, a well documented Fishbone session can be used for similar issues that occur elsewhere in the plant or in the manufacturing network at large. Its easy to share the document with sister facilities to use as a starting point for their problem-solving process.
The Fishbone Diagram is one of my personal favorite Lean tools because anyone can learn and apply it effectively. If you can manage to get your floor operators walking through an informal Fishbone process as issues occur on the production floor, you have a very solid foundation for a Lean implementation and problem-solving culture. Just make sure your manufacturing support teams, including management, have the capability to support the floor operators as needed in their problem-solving efforts.
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