quarta-feira, 5 de setembro de 2012
Quality Tools – The Five Whys
Today I will introduce one more tool on the analysis of causes of problems, the technique of the five whys. This simple methodology was developed in the Toyota Production System also known as Lean Manufacturing and Lean Production also in the 80's, the Toyota car factory. This model and the constant philosophical and technological revolutions have made Toyota a leader in this market segment. The technique is to ask why five times the event of a problem. We present the tool by way of example to facilitate understanding.
A chocolate factory receives many complaints about their final product and quality engineer decides to use the methodology of the 5 whys with your team.
Most complaints say that chocolate is no longer crunchy as before.
Let´s put the five whys in action!
1 - Why chocolate is not crunchy?
Because the product arrives too late and the customer loses their original production.
2 - Why does the product arrives too late to the customer?
Because the carrier can not deliver on time.
3 - Why the carrier does not deliver on time?
Because it performs only one trip a week carrying a large amount of products.
4 - Why it only makes a weekly trip?
For the chocolate factory delivering identified that in once weekly throughout their production, transportation costs would be reduced.
5 - Why did she decided to reduce shipping costs?
To increase profit.
We could go on asking several questions, but we have an important conclusion for this example. The chocolate factory decided to increase its gain by reducing their operating expenses in the case of transport costs. But making that decision, she has (perhaps unknowingly) giving up the quality of their product, because the chocolates now no longer as crisp customers who require this as a requirement of the product. So, an example of corrective action would be more flexible delivery, thus avoiding this problem.
We realize that sometimes makes one question we did not reach the root cause of the problem, we must seek the causes in more detail so that our actions are effective. So I ask: Why should five whys? Actually this is not a rule, is only a guideline to check thoroughly the causes of a problem avoiding the first or second stop why. Go ahead, because the higher the precision, the better the result.
This method in some cases is somewhat limited, as many could be the ramifications of the causes and content, so I suggest you also know the Ishikawa Diagram, famous Fishbone Diagram or Cause and Effect to complement this learning.