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August 16, 2006
4.1 million by 3.4 defects per million is?
Following some discussion on batteries and the Dell recall, someone took out the calculator and did their sums. Over at Computerworld, Sony spokesman Rick Clancy is reported to have said:
"It's a number you can count on two hands," Clancy said, adding that it is inconsequential "when you look at it by Six Sigma standards." Six Sigma is a measure of engineering quality that ensures a process will not produce more than 3.4 defects per million opportunities."
Now, that doesn't sound like much. But one of my respondents (a former manufacturing manager) whipped out her (mental) calculator and we spoke Six Sigma for a while. 3.4 defects per million? If you sell 4 million batteries, there's at least 13 batteries waiting to explode some where. OhMiGosh! Think of the product liability exposure even when things are doing well, Six Sigmawise. Think of the numbers if there was a genuine weakness in the product or it's manufacturing.
Time to lift the mean, sharpen the bell curve, lose the tail. Or give up Manufacturing and take up Law.
Posted by Anandasim at August 16, 2006 07:36 PM
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Comments
Very true, Ananda, but wouldn't you be annoyed if one of those batteries Sigmaed it's way into oblivion while it was plugged into your machine and maybe sitting on your lap?
Why do we Xray everyone that goes on a jet? I mean, how many million passengers jumped on planes this morning, and how many harboured terrorist thoughts? What are the odds?
We insure against the possibility of small things happening by taking these extra-ordinary measures. If Dell hadn't recalled it's batteries, I'm sure someone somewhere would have posted a scathing blog on how Dell doesn't really care about it's customers etc etc.
Posted by: Newman at August 17, 2006 10:39 AM
Ha! Its true that SixSigma is a measure of engineering quality through the use of a standard approach and process to ensure product design and quality by understanding the qualities of a sum of the parts under defined conditions.
Using any measuring device & engineering system doesn't guarrantee you will reach the desired 3.4dpo. This measure is only apt to the tools and system that you use.
The ability to hit this target depends strictly on the engineering and technical know-how of the company involved.
Marketing decisions, business pressure and design considerations sometimes mean that you accept a lower standard of engineering to produce a product of high quality. Maybe this was the case with Dell's batteries, and maybe even some other laptop battery suppliers.
It might be also of consideration that (I'm assuming) that an exploding fireball of a battery is considered a dpo by Rick Clancy, and not a battery that loses capacity within guarranteed period. This line is known as Upper Specified Limit (USL) in Six Sigma.
SixSigma you'll know 'how' it will behave under the testing conditions. As you could appreciate, testing conditions might not always reflect real life usage and thus a testing condition can be overlooked and may cause a problem.
So, where does the consumer want to place your USL? A battery that doesn't lose capacity over 1-2 years of normal use, or one that catches on fire? I know I want the former and not the latter.
Tim
Posted by: Timmy B ![[TypeKey Profile Page]](http://bleedingedge.com.au/blog/nav-commenters.gif)
at August 17, 2006 01:59 PM