PRINTED PAGE UNCONTROLLED STATISTICAL PROCESS CONTROL WC) REFERENCE MANUAL Issued 1992, Second Printing March 1995 (new cover only) Copyright0 1992,O 1995 Chrysler Corporation, Ford Motor Company, and General Motors Corporation PRINTED PAGE UNCONTROLLED Selection Procedure for the Use of the Control Charts Described in This Manual DETERMINE CHARACTERISTIC TO BE CHARTED NONCONFORMlTlES YES CONDUCIVE TO SUBGROUP SAMPLING - e.g., CHEMICAL YES USE CHART FOR INDIVIDUALS: X-MR Note: This chart assumes the meas- urement system has been assessed and is appropriate PRINTED PAGE UNCONTROLLED FOREWORD This Reference Manual was prepared by the quality and supplier assessment staffs at Chrysler, Ford and General Motors, working under the auspices of the Automotive Division of the American Society for Quality Control Supplier Quality Requirements Task Force, in collaboration with the Automotive Industry Action Group. The ASQCIAIAG Task Force charter is to standardize the reference manuals, reporting formats and technical nomenclature used by Chrysler, Ford and General Motors in their respective supplier assessment systems: Supplier Quality Assurance, Total Quality Excellence and Targets for Excellence. Accordingly, this Reference Manual can be used by any supplier to develop information responding to the requirements of either Chrysler’s, Ford’s or General Motors’ supplier assessment systems. Until now, there has been no unified formal approach in the automotive industry on statistical process control. Certain manufacturers provided methods for their suppliers, while others had no specific requirements. In an effort to simplify and minimize variation in supplier quality requirements, Chrysler, Ford, and General Motors agreed to develop and, through AIAG, distribute this manual. The work team responsible for the Manual’s content was led by Leonard A. Brown of General Motors. The manual should be considered an introduction to statistical process control. It is not intended to limit evolution of statistical methods suited to particular processes or commodities nor is it intended to be comprehensive of all SPC techniques. Questions on the use of alternate methods should be referred to your customer’s quality activity. The Task Force gratefully acknowledges: the senior leadership and commitment of Vice Presidents Thomas T. Stallkamp at Chrysler, Clinton D. Lauer at Ford, and Donald A. Pais at General Motors; the technical competence and hard work of their quality and supplier assessment teams; and the invaluable contributions of the Automotive Industry Action Group (under AIAG Executive Director Joseph R. Phelanl in the development, production and distribution of this Reference manual. We also wish to thank the ASQC reading team led by Tripp Martin of Peterson Spring, who reviewed the Manual and in the process made valuable contributions to intent and content. Bruce W. Pince Task Force Coordinator Sandy Corporation Troy, Michigan December, 1991 This Manual is copyrighted by A.I.A.G., all rights reserved, 1991. Additional copies can be ordered from A.I.A.G., and/or permission to copy portions of the Manual for use within supplier organizations may be obtained from A.I.A.G. at (313) 358-3570. PRINTED PAGE UNCONTROLLED ACKNOWLEDGEMENT The joint consensus on the contents of this document was effected through Task Team Subcommittee Members representing General Motors, Ford, and Chrysler, respectively, whose approval signatures appear below, and who gratefully acknowledge the significant contribution of Pete Jessup of the Ford Motor Company, who was responsible for developing the majority of the material found in Chapters I, II, and III, and the Appendix of this document. Harvey Goltzer of the Chrysler Corporation contributed concepts relative to process capability and capabil- ity studies, found in the introduction section of Chapter I. Jack Herman of Du Pont contributed some of the concepts relative to capability and performance indices and the importance of measurement variability, found in portions of Chapters II and IV, respectively. The General Motors Powertrain Division contributed the discussion and examples relative to subgrouping and process overadjustment. The section in Chapter II which provides understanding of process capability and related issues was developed by the General Motors Corporate Statistical Review Committee. This committee also contributed to the development of Chapter IV, Process Measurement Systems Analysis, as well as to some Appendix items. Finally, valuable input to all sections of the manual was provided by ASQC representatives Greg Gruska, Doug Berg, and Tripp Martin. Leonard A. Brown, G.M.Victor W. Lowe, Jr., FordDavid R. Benham, Chrysler December 1991PRINTED PAGE UNCONTROLLED