Process Capability Analysis

* Process Capability Analysis

 

: 제조 공정을 안정 상태로 유지한 경우 그 공정이 만들어내는 품질의 달성 능력을 말한다.

[네이버 지식백과] 공정 능력 [process capability, 工程能力, こうていのうりょく] (용어해설)

 

- Cp, Cpk, Cpkm

 

- C.I and Hypothesis testing for Cp

 

* Process Capability Ration : Cp = distance between specification limits / 6*sigma

 

 

 

- 프로세스가 양측 규격인 경우 적용

 

- Cp = 1 means the process are uses up 100% tolerance band with 0.27% (2700ppm) nonconforming units for a normal distribution.

 

- Percentage of the specification band used up by the process

 

  P = (1/Cp) 100%

 

 

* A measure of Actual capability

 

 

- 프로세스가 한쪽 규격이 주어진 경우 적용

 

- If the process is centered, then Cp = Cpk

 

   If not centered, then Cpk < Cp

  

- Cp measures potential capability and Cpk measures actual capability

 

 

* More about Process Capability index

  

 

​- 0 <= Cpkm <= Cp ,

 

- Cp: the first generation process capability ratio

   Cpk : the second generation PCR

   Cpkm : third generation PCR

 

 

* Confidence Interval for PCR

 

 

 

 

* Review of SL, CL and NTL

 

​(Source/ 출처: ISyE512 Lecture slide U of WISC, Prof. Kaibo Liu.)