The 5 Whys Theory - Practical application to improve your service rate
24/06/2024
Reading time: 8 minutes
The "5 Whys" theory originates from Toyota's production system, famous for its innovative approach in the field of automobile manufacturing. This methodology, also known as the "5 Whys Root Cause", was developed as part of the Toyota Production System (TPS) to solve operational problems thoroughly and sustainably.
The genesis of the method dates back to the mid-20th century, when Taiichi Ohno, chief engineer at Toyota, was looking for ways to improve efficiency and quality in production. Faced with recurring problems on the production line, Ohno developed the "5 Whys" technique as a systematic tool to analyze the root causes of issues. The idea was not just to address the obvious symptoms but to delve deeply to understand the underlying roots of the problems.
The functioning of the "5 Whys" relies on an iterative questioning process. When a problem is identified, the first question "Why?" is asked to determine the immediate cause. The answer to this question then becomes the basis for the second question "Why?", and so on, until the root cause is reached. The goal is to repeat this process about five times, hence the name of the method. The "5 Whys" encourage a deep exploration of problems rather than a simple surface resolution.
The practical application of the "5 Whys" occurs in various contexts, ranging from industrial production to project management and daily problem-solving. The method is particularly effective in addressing recurring issues, hardware failures, process errors, and other operational challenges. For example, if a defect is found on a production line, the "5 Whys" will help identify the root causes, such as failures in preventive maintenance or gaps in operator training.
Practical case - Optimization of production organization: A Deep Exploration through the "5 Whys" Theory
As the continuous improvement manager at our factory, I am tackling a major challenge: recurring delays in delivering our products to customers. To address this, I have decided to apply the "5 Whys" methodology to identify the root causes of our site's delays and develop appropriate solutions.
1️⃣ Why do we have delivery delays?
A preliminary analysis of the lead times compared to our production range shows that the production of the work orders (OFs) is generally started ahead of the need. These delivery delays are thus due to excessively long production times relative to the targets. There is particularly high volatility in the lead times at the machining station.
2️⃣ Why are the lead times very heterogeneous at the machining station?
In discussions with the operators, we notice that they struggle to prioritize one work order (OF) over another and tend to take the highest one from the stack. Delving into the operational details, we identify that the lack of priority on the production in progress creates major inefficiencies.
3️⃣ Why don't our operators prioritize the right products?
We then examine why our operators are unable to establish a clear priority on the production in progress. We discover that the absence of a priority concept complicates the operators' tasks, as they lack clear indicators to guide their actions.
4️⃣ Why are products at risk of delay not prioritized?
By posing the third question, "Why," we investigate why products at risk of delay are not adequately prioritized. It becomes evident that many products share the same delivery date, but without clear indications of the projected delay for each, the operators lack visibility on which ones truly require special attention based on what remains to be produced.
5️⃣ Why is there no notion of projected delay for each product?
Our fourth question digs deeper into why no notion of projected delay is integrated into our process. It appears that the lack of tools for calculating projected delay and effective communication with operators creates a major gap in our ability to anticipate and manage potential delays.
✅ Solutions and Implementations
Guided by these discoveries, our action plan is taking shape. We plan to introduce a priority system on the production in progress, establish clear criteria for identifying at-risk products, and implement a tool for calculating the projected delay for each product. Our research has led to a study of a "best-of-breed" scheduling and production management solution.
In this case, the scheduling and production management module from Oplit is a good solution to provide the necessary visibility to operators by making visible:
The projected delay of each work order based on its advancement relative to the range
Simply visualizing fast tracks and urgencies
Having transparency on the production of upstream/downstream stations to anticipate upcoming urgencies and monitor the proper progress of production
⚠️ The limits of this theory
The benefits of the "5 Whys" lie in their ability to identify the underlying causes of problems, prevent recurrences, and promote a culture of continuous improvement. However, it is crucial to recognize the limits of the method, notably its risk of excessive simplification and its dependence on the experience of the individuals involved. It is recommended to complement the "5 Whys" approach with other problem-solving techniques to ensure a comprehensive analysis.
In conclusion, the "5 Whys" theory has emerged as a powerful and systematic approach to solving problems by tracing back to the fundamental causes. Its adoption in various fields attests to its effectiveness, making the "5 Whys" a key method in continuous improvement and proactive management of operational challenges.
