Compendium admissions 2023-25
Download 4.08 Mb. View original pdf
|
- Navigate this page:
- Capability Indices
| Sigma level Sigma (with 1.5σ shift) DPMO Percent defective Percentage yield Short- term C pk Long- term C pk 1 −0.5 691,462 69% 31% 0.33 −0.17 2 0.5 308,538 31% 69% 0.67 0.17 3 1.5 66,807 6.7% 93.3% 1.00 0.5 4 2.5 6,210 0.62% 99.38% 1.33 0.83 5 3.5 233 0.023% 99.977% 1.67 1.17 6 4.5 3.4 0.00034% 99.99966% 2.00 1.5 7 5.5 0.019 0.0000019% 99.9999981% 2.33 1.83 Capability Indices Process capability is the ability of the process to meet the requirements set for that process. Capability indices determine process capability concerning variation and proximity to the target. They are used for continuous data and are unitless statistics or metrics. C p • It is the potential capability indicating how well a process could be if it were centered on the target. This is not necessarily its actual performance because it does not consider the location of the process, only the spread. It doesn't consider the closeness of the estimated process mean to the specification limits. • It compares the width of two-sided specification limits to the effective short-term width of the process. • The specification width is the distance between USL and LSL. 81 • To determine the process width, Six Sigma practitioners defined any process’s effective limits as three standard deviation limits from the average. Ina normally distributed population, 99.73% of the variation is within ± s of the Process Average and therefore considered as process width. • C p only compares the width of specification and process therefore, any change of process average isn’t accounted for in C p. Download 4.08 Mb. Share with your friends:
|