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• #27033

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I am repeating my question once again, I hope this time I may get some help..

Our customer accepts the goods we supply at AQL 2.5,
now that I am analyzing the situation based upon DPMO,
on an average there are 106 opportunities in an unit to go wrong. Your guess is right, we are doing 100% inspection at the end of assembly line for discrete parameters while sampling inspection for variables.

Because of availability of high opportunities I am getting a larger value for sigma. For example

# inspected = 75
# passed = 60
# failed = 15 (deviations in 15 opportunities)

Total number of opportunities available =106×75
Defects per opportunities = 0.001887
Defects per million opportunities = 4.37

So if I consider that my customer say demands somewhere around 3 sigma, our process is performing at4.37 sigma.

Say from the same kind of a lot our customer picks up 2
deviations he orders for rescreen. This is where I am
puzzled.

On the other hand what seems to me is, 15 failed out of
75 directly gives the process rate as 2.33 sigma, this has more relevance to practical applications which I am currently using.

If I consider the AQL table supplied by the customer on
the basis of accept and reject numbers converted to
opportunities, the expectations come to an average of
5.5 sigma.

This value has a practical relevance to my above said
value of 4.37. Since I am very well aware that we are not up to the mark with customer expectations about quality these were my conclusions, tell me if you agree upon the given details.