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My Friend Bob’s Yield Challenges

I have spoken about Quality philosophies previously and have stated how important it is to apply the correct methodology and to not become a slave to any.

In this article, I am going to introduce you to my friend Bob and how the use of the essentials of Six Sigma helped him many years ago.

My friend Bob and I worked for a major Corporation in the 1990s. Bob was assigned the task of improving the quality of the core product we were making as the yield was so poor our ability to predict shipments was terrible and affecting sales.

Every day, Bob diligently analysed every defect that contributed to failures seen in the factory and determined what was the reason for each defect. Since our yields were so bad there were hundreds of defects so focussing his efforts on defects that contributed most to the percentage failure made complete sense. This was our introduction to the Pareto chart.

Bob diligently put pragmatic corrective actions in place.

Every month Bob had to present his findings, actions, and results to one of the corporate VPs.

It was usually in the form of a Pareto chart (Of the form below) and the associated corrective actions with assigned responsible persons and expected dates.

The VP that we presented to listened to what Bob had to say and indicated that if he has solved specific issues (Let’ use Spelling errors and Missing Description Tag as examples) then in the next presentation the yield should have risen by about 25%. So if the first time yield was 80% one would expect it to be 85%. This was simple mathematics and seemed quite logical.

So over the following four weeks, Bob continued down the same path and at the section of the meeting with the VP he presented the yields. Week after week, despite all the efforts and many corrective actions, the yield was exactly the same.

Clearly, there was something happening that Bob and the rest of us did not understand.  

Extra help was required, and it came in the form of experts from the USA as well as rolling out six sigma training to every engineer.

I had not understood statistics particularly well at school or University but thankfully our trainer did not get into complex mathematics but focussed on what methods to use. They were often supplemented with stories to reinforce the point. He introduced us to the following:

Trend and Pareto charts, averages, standard deviations, Cp & Cpk, Red Xs and Pink Ys

With these we could achieve almost anything and in the specific case with my friend Bob, using these few tools we ultimately were able to significantly improve the first time yield.

Sadly we were never able to improve the yield to the level we wanted to. We had learned that the despite all of the efforts we could make the overall design was not capable of being manufactured to that yield. It was said to have a poor Cpk.

Future designs iteratively did allow us to remove many of the issues and gradually improve the product.

Ultimately this was a significant contributor to our ability to design products for the future.

It is true that as an employee of a large corporation 25 years ago, we had access to many resources that SMEs can only dream of.

Design and manufacture are constantly evolving, there are always issues. Adopting systematic good practices such as those described as well as calling on people like Bob and I who have walked this path who can help.

Additionally, tools that were only accessible to a few rich companies in the past are just as relevant today as they were 25 years ago but now are often commoditised, cheap or even free.

We are in a time where even modestly funded SMEs can adopt best practices and compete with the largest corporations.

In following articles I will introduce to you, as was introduced to Bob and I these different methodologies in some details that

If you would like to know more please contact me via my website, facebook or LinkedIn.

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