1、I EIA STANDARD Guideline on the Use and Application of Cpk EIA-738 SEPTEMBER 1997 (Reaffirmed May 2001) ELECTRONIC INDUSTRIES ALLIANCE GOVERNMENT ELECTRONICS GND INFORMATION TECMNOLOGY ASSOCIATION A SECTOR OF Elsctronic Industries Alliance Copyright Government Electronics hence, they may severely un
2、derestimate true process variability. In addition, the appropriateness of the constants d2 and c4 is dependent upon the underlying distribution of the base data being normal, i.e., Gaussian. If this is true, and the process is in, or near, a “state of statistical control“, then these estimators will
3、 give essentially the same results. Copyright Government Electronics however, this does not imply strict rigidity. When knowledge of a process or product increases to the level that procedures for estimating Cpk should be altered, then such changes should be made, documented, and a new base point es
4、tablished. It is important for an organization involved in supplier evaluation via Cpk to realize that the greatest value of Cpk will often not be the actual number obtained. The greatest value of Cpk will most likely be as a discussion topic to initiate dialogue towards stronger and more cooperativ
5、e supplierhstomer relationships. Copyright Government Electronics then the relevant product variance estimate becomes A 4 d = s? - s2 -1 This is certainly not the only way to account for measurement enor; however, it is one rather simple, straightforward approach. Another example of the use of varia
6、nce components in estimating o involves the proper inclusion of among-subgroup variability in the estimate. An estimate of this component of variability can be obtained as where n = the number of observations in each subgroup, and - G i=i = (l/(G-l)X (Z, - X)2 Mean S2 Copyright Government Electronic
7、s Cheng, Smiley W.; and Spiring, Frederick A., “A New Measure of Process Capability: Cpm“. Journal of Oualitv Technology, vol. 20, no. 3, July 1988, pages 162-175. (3) Chou, Owen, and Borrego A., “Lower Confidence Limits on Process Capability Indices“, Journal of Oualitv Technology, Vol. 22, No. 3,
8、July 1990, pp. 223-229. (4) Clements, John A., “Process Capability Calculations for Nonnormal Distributions“. Ouality Promess, September 1989, pages 95-100. (5) Duncan, Acheson J., Oualitv Control and Industrial Statistics, fifth edition. IRWIN, Homewood, Illinois 60430. 1986. (6) Gunter, Berton H.,
9、 “The Use and Abuse of Cpk“. Oualitv Progress. Part 1, January 1989, pages 72-73. Part 2, March 1989, pages 108-109. Part 3, May 1989, pages 79-80. Part 4, July 1989, pages 86-87. Correction, September 1989, page 11. “The Use and Abuse of Cpk Revisited“, January 1991, pages 90-94. (7) Holmes, Donald
10、 “Basic Training Review: A Quality Portfolio Management Chart“. Quality, December 1987, page 67. (8) James, Paul C., “Basic Training Review: Cpk Equivalencies“. Ouality, September 1989, page 75. (9) Kane, Victor E., “Process Capability Indices“. Journal of Oualitv Technolow, vol. 18, no. 1, January
11、 1986, pages 41-52. Corrigenda, vol. 18, no. 4, October 1986, page 265. (10) Kirch, Andrew R., “Some Challenges in the Application of SPC to Complex Manufacturing Processes“. 3M Company. October 23, 1986. (1 1) Mullenix, Paul D., “The Capability of Capability Indices with an Application to Guardband
12、ing in a Test Environment,“ International Test Conference Proceedinns, 1 990, IEEE, pp. 907-915. (12) Pennucci, Nicholas J., “Tech Briefs: Creating a Process Model for SPC“. Machine Desim, January 12, 1989, pages 138-140. Copyright Government Electronics & Information Technology Association Reproduc
13、ed by IHS under license with GEIA Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-h EIA-73 8 Page 14 REFERENCES AND BIBLIOGRAPHY (Cont) (13) Rado, Leonard G., “Enhance Product Development by Using Capability Indexes“. uality Promess, Apd 1989, pages 38-41. (14) Whe
14、eler, Donald J. and Lyday, Richard W., EMP - Evaluating the Measurement Process, second edition. SPC Press, Inc., 5908 Toole Drive, Suite C, Knoxville, Tennessee 37919, 1989. (1 5) “General Requirements for Implementation of Statistical Process Control“, Institute for Interconnecting and Packaging E
15、lectronic Circuits, 73 80 N. Lincoln Ave., Lincolnwood, Illinois 60646, 1990. (16) “Glossary and Tables for Statistical Quality Control“, Third Edition, Amencan Society for Quaiity Control, Statistics Division, 3 10 West Wisconsin Avenue, Suite 500, Milwaukee, Wisconsin 53203, 1996. Copyright Govern
16、ment Electronics & Information Technology Association Reproduced by IHS under license with GEIA Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-Y Document No. EIA Document Improvement Proposal Document Title: If in the review or use of this document, a potential ch
17、ange is made evident for safety, health or technical reasons, please fill in the appropriate information below and mail or FAX to: Signature: Electronic Industries Alliance Technology Strategy & Standards Department - Publications Office 2500 Wilson Blvd. Arlington, VA 2220 1 FAX: (703) 907-7501 Dat
18、e: Submitters Name: Telephone No.: FAX No.: e-mail: Address: Urgency of Change: Immediate: 0 At next revision: 0 Problem Area: a. Clause Number and/or Drawing: b. Recommended Changes: c. Reasonktionale for Recommendation: Additional Remarks: _ Responsible Committee: Chairman: Date comments forwarded to Committee Chairman: Copyright Government Electronics & Information Technology Association Reproduced by IHS under license with GEIA Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-
