When an incident occurs at a production facility, it is important not just to eliminate its consequences, but to understand why it happened.
This is the only way to prevent a recurrence.
One of the most effective tools for this is the "5 Whys" method, developed in the 1930s by Sakichi Toyoda, the founder of Toyota.
🔍 How the method works
The method is based on a simple principle: to get to the root cause, you need to ask the question "Why?" several times.
Usually, five steps are enough to move past superficial factors and see the true cause.
📉 On a diagram, it looks like this:
Problem → Why? → Why? → Why? → Why? → Root cause
The main goal is not to find someone to blame, but to determine which process or system failed.
⚙️ How to apply it
📘 Example
Problem: Equipment stoppage.
Why? A fuse blew.
Why did it blow? The motor overloaded.
Why did it overload? The feed mechanism is jamming.
Why is it jamming? There is no lubrication.
Why is there no lubrication? Checking the lubrication level is not included in the maintenance schedule.
✅ Root cause: Lack of scheduled equipment checks.
Corrective action: Add a lubrication checkpoint to the maintenance plan, assign a responsible person, and set deadlines.
📍 The main rule:
Keep asking "why?" until it becomes clear that the identified cause is truly the root cause.
💡 Why it is important
It helps identify true causes rather than superficial factors.
It builds a systematic approach to safety.
It makes corrective actions deliberate and effective.
It increases reliability and the Safety Culture at the production facility.