What is 5 Why?

5 Why analysis is one of the Six Sigma tool which is very useful tool adapted in most of the industries. The ultimate goal of 5 Why analysis is to dig the real cause of the problem. This methodology was developed by Japanese industrialist and Inventor, Sakichi Toyoda (Founder of Toyota Industries). The 5 Why's was first applied to the motor manufacturing of Toyota Motor Corporation.

Examples of 5 Why's:

Problem: Robotic Arm stopped working

1.   Why robotic arm stopped working?
Because Circuit has overloaded, causing a fuse to blow

2.   Why is the circuit overloaded?
There was insufficient lubrication on the bearing, so they locked up

3.   Why was there insufficient lubrication on the bearing?
The oil pump on the robotic arm is not circulation sufficient oil.

4.   Why is the pump not circulating sufficient oil?
The pump intake clogged with metal shaving.

5.   Why is the intake clogged with metal shaving?
Because there is no filter on the pump.

As showed in above example, the root cause behind the failure of robotic arm was “no filter on the oil pump”. In most cases you will find your solution to the problem by using 5 Why analysis, but if you are still not satisfied with the solution you can continue with more “Why’s”.
After finding the root cause with 5 Why analysis you need to take corrective actions to solve the problem and preventive action to prevent the problem from occurring again in future.

For exercise use the below templates.


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