5 why why analysis

5 Why-Why analysis is also popularly known as 5-Why problem solving tool. It’s a simple and effective problem-solving tool that is used widely in many industries.

The principal of 5 why why analysis is very simple, by asking ‘why’ five times a problem investigator can discover the real root cause of the problem.

Who developed the 5 why why analysis tool?

5 Why problem-solving developed in 1930 by Sakichi Toyoda, the Japanese industrialist and founder of the Toyota industries.

How to use the 5 why why analysis / problem solving tool?

Define the problem: The first step of using 5-Why is to define the problem with a clear description by considering the following factors,

• What went wrong?
• Where the problem/defect observed?
• When the problem recorded/observed?
• Who reported the problem/defect?

Team formation: This is a very important step for the selection of the right team member for problem-solving. It’s better to select team members who are familiar with the problem Subject matter experts can add lots of value to the problem-solving process. For example, an operator who daily handles machines, production processes, can add more accurate information in the problem-solving process.

Brainstorming: It’s better to conduct a brainstorming session on-shop floor or the place where the problem/defect arose. Conducting 5-Why analysis at a spot/station will help to discover a real root cause of the problem. The first question may look simple to ask, but it’s challenging to gain the right answer. First question it-self quick off brainstorming process. Team members co-relates problem statement with a different scenario and find out a first cause (answer) of the first question. Subsequently, remaining 4 Why question helps to find out a root cause of the problem.

Corrective Action: After the brainstorming session, the next step is determining corrective action to resolve each root cause identified in the 5-WHY analysis. Corrective action of each root cause carefully evaluated. It’s better to gain team members’ suggestions, input to build a better and effective corrective action.

Problem Statement: 100kg of batter rejected in the food industry after detecting the oil contamination (at one of the batter mixing machine) during a mandatory first batch production approval at the food lab.

1st WHY: Why batter is contaminated?
Cause (Answer): Small quantity of oil drained from batter mixing machine shaft during batter mixing process?
2nd WHY: Why oil drained from batter mixing machine shaft?
Cause (Answer): Batter machine shaft seal was damaged.
3rd WHY: Why shaft seal was damaged?
Cause (Answer): Shaft seal was affected due to non-food grade oil usage for lubrication.
4th WHY: Why non-food grade oil used for lubrication?
Cause (Answer): Machine maintenance operator was not aware of food-grade oil usage for lubrication.
5th WHY: Why operator was not aware of food-grade oil usage for lubrication?
Cause (Answer): Batter mixing machine maintenance plan does not specify food-grade oil usage for lubrication.

In this way, 5-Why analysis can be conducted to solve the problem. Corrective action for this problem would be,

1. Usage of food-grade oil for lubrication
2. A maintenance plan should specify the type of food-grade oil and it’s a quantity.
3. Operator training for usage of food-grade oil for lubrication of food contact machinery.

Refer following 5Why Analysis Template

When to use 5 why why analysis?

5-Why/why-why analysis is more useful and suitable for solving a simple problem. The 5-why tool is not a practical tool to solve a complex and critical problem. 5 Why analysis problem-solving tool is very effective to solve a simple problem. For complex problem-solving fish-bone diagram is the best option.

Along with 5 why-why additional open and close-ended questions can be included to discover the root cause.

Please do watch a small video tutorial about Quality control (7QC) tools.

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