Question

Suppose that a process is currently operating at a 3.5-sigma quality level, and it is planned to use improvement projects to move this process to a 6-sigma level? What project improvement rate would be necessary to achieve that new performance in 2 years?

Answer 1

Answer:

$11,373 PPM$

Step-by-step explanation:

The following  formula is used to compute the Proportion of error-free units given the sigma level in Excel.

 The proportion of error-free units = NORMSDIST(Sigma Level - 1.5)

Suppose that a process is currently operating at a 3.5-sigma quality level.

The proportion of error-free units for this process is

                           NORMSDIST(3.5 - 1.5) = 0.977250

Therefore, the rejection rate is equal to

                  $1 - 0.977250 = 0.022750$

or 22750 PPM.

Now, consider a 6-sigma level process.

The proportion of error-free units equals

                     NORMSDIST(6.0 - 1.5) = 0.9999966

and the rejection rate is

                             $1 - 0.9999966 = 3.4 PPM$

Hence, reduction is PPM required per year , that is

                              $\dfrac{22750 - 3.4}{2} = 11,373 PPM$

reduction per year