1、 AEROSPACE RECOMMENDED PRACTICE Statistical Product Acceptance Requirements Using Process Control Methods SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and i
2、ts applicability and suitability for any particular use, including any patent infringement arising therefrom, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comme
3、nts and suggestions. Copyright 2005 SAE International All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of S
4、AE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA) Fax: 724-776-0790 Email: custsvcsae.org SAE WEB ADDRESS: http:/www.sae.org Issued 2005-10 ARP9013/3 FOREWORD To assure customer satisfaction, aerospace industry organizations shall produce, and c
5、ontinually improve, safe, reliable products that meet or exceed customer and regulatory authority requirements. The globalization of the aerospace industry, and the resulting diversity of regional/national requirements and expectations, has complicated this objective. End-product organizations face
6、the challenge of assuring the quality of, and integrating, product purchased from suppliers throughout the world and at all levels within the supply chain. Aerospace suppliers and processors face the challenge of delivering product to multiple customers having varying quality expectations and requir
7、ements. The aerospace industry established the International Aerospace Quality Group (IAQG) for the purpose of achieving significant improvements in quality and safety, and reductions in cost, throughout the value stream. This organization includes representation from aerospace companies in the Amer
8、icas, Asia/Pacific, and Europe. This recommended practice has been prepared by the Americas Aerospace Quality Group (AAQG). This document standardizes, to the greatest extent possible, the requirements on product acceptance using process control and monitoring techniques in the aerospace industry. S
9、AE ARP9013/3 - 2 - TABLE OF CONTENTS FOREWORD.1 1. SCOPE 3 1.1 Purpose3 1.2 Field of Application.3 2. REFERENCES.3 2.1 Applicable Documents .3 2.2 Definitions 4 3. REQUIREMENTS 4 3.1 Data4 3.2 General Conditions 4 3.3 Statistical Stability and Process Control.5 3.4 Capability .6 3.5 Process Monitori
10、ng Frequency 8 3.6 Recall System 8 3.7 Limiting Measurement and Recording Errors.8 3.8 Evaluating Effects of Corrective Actions 8 3.9 Correlation Studies and Experimentation.8 APPENDIX A GUIDELINES AND RECOMMENDATIONS FOR SUCCESSFUL IMPLEMENTATION9 APPENDIX B CONFIDENCE INTERVALS AROUND CPK FOR A NO
11、RMALLY DISTRIBUTED PROCESS.12 SAE ARP9013/3 - 3 - 1. SCOPE: 1.1 Purpose: ARP9013/3 recommended practice specifies a product acceptance system using process control methods. Its purpose is to assure conformance for specified characteristics. Use of process control techniques for product acceptance re
12、quires maintaining process stability and capability. A stable and capable process is the best assurance of conforming hardware for the customer. There can be lower inspection costs associated with a process control acceptance approach. 1.2 Field of Application: These methods can be used for product
13、acceptance when the process is well understood and stability is monitored. The rules provided herein ensure protection for the customer in the event that a deterioration in process stability or capability occur; and an incentive to reduce inspection costs by means of process controls to consistently
14、 achieve good quality. 2. REFERENCES: 2.1 Applicable Documents: The following publications form a part of this recommended practice to the extent specified herein. The latest issue of SAE publications shall apply. The applicable issue of other publications shall be the issue in effect on the date of
15、 the purchase order. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. 2.1.1 SAE Publications: Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (
16、outside USA), www.sae.org. ARP9013 Statistical Product Acceptance Requirements AS9100 Quality Systems - Aerospace - Model for Quality Assurance in Design, Development, Production, Installation and Servicing AS9103 Variation Management of Key Characteristics 2.1.2 ANSI/ASQC Publications: Available fr
17、om the American Society for Quality (ASQ), 600 North Plankinton Avenue, Milwaukee, WI 53203, Tel: 800-248-1946 or 414-272-8575, www.asq.org. ANSI/ASQC B1 Guide for Quality Control Charts ANSI/ASQC B2 Control Chart Method of Analyzing Data ANSI/ASQC B3 Control Chart Method of Controlling Quality Duri
18、ng Production SAE ARP9013/3 - 4 - 2.2 Definitions: See ARP9013 paragraph 2.3. 3. REQUIREMENTS: Applicable requirements defined in ARP9013 shall be followed when using this specification. This ARP9013/3 recommended practice provides additional requirements for accepting products based on process cont
19、rols. Where statistical process control (SPC) tools are used to meet these requirements, all requirements of ANSI/ASQC B1 (Guide for Quality Control Charts), B2 (Control Chart Method of Analyzing Data) and B3 (Control Chart Method of Controlling Quality During Production) shall be satisfied. 3.1 Dat
20、a: Some regulatory agencies require that data of a quantitative nature shall be available that is sufficiently correlated with the acceptance criteria. If attribute data is allowed, the data shall show sufficient ability to predict the acceptability of affected characteristics. See Appendix A for gu
21、idance. 3.2 General Conditions: The following shall be in place at the organizations process site: 3.2.1 Measurement Systems: See ARP9013 paragraph 3.6. 3.2.2 Training Program: Training shall be required as stated in ARP9013 paragraph 3.1. Additional training for process control techniques shall ass
22、ure the operators understanding of (a) the use and interpretation of all relevant process control tools; and (b) the appropriate and timely corrective action required when any process control requirement is violated. 3.2.3 Process Control Points: Material and product control between process control
23、points, shall be adequate to maintain conformance of the characteristics specified as process control characteristics. The organization shall be responsible for conformance of all characteristics between the last process control point and shipping to the customer. 3.2.4 Process Control Acceptance Pl
24、ans and Records: Requirements for statistical product acceptance plans and records shall apply, see ARP9013 paragraph 3.8. See AS9103 for further recommendations. 3.2.5 Unbiased Sampling: See ARP9013 paragraph 3.4. SAE ARP9013/3 - 5 - 3.2.6 Time or Production Ordered Sequence: Any samples used for p
25、rocess control purposes shall be recorded and maintained in time or production sequence. See Appendix A for guidance. 3.2.7 Data Retention Plan Defined: See ARP9013 paragraph 3.8. 3.2.8 Internal Audits: See ARP9013 paragraph 3.10. 3.3 Statistical Stability and Process Control: 3.3.1 Product shall be
26、 accepted on the basis of process control only when one or more of the following has been satisfied: a. SPC control charts with established control limits based on n subgroups, where n is typically at least 20 subgroups of data. See Appendix A for guidance. b. Tool stops or other variation restricti
27、ng mechanisms, control of process settings such as “bought off CNC programs,” standard processes, and/or mistake-proofing devices shall satisfy independent review as being adequate and consistent with the applicable quality parameter. See Appendix A for guidance. c. Process parameter controls shall
28、satisfy independent review as being adequate and be consistent with the applicable quality parameter. See Appendix A for guidance. 3.3.2 The controls of 3.3.1 shall assure the ongoing stability in both process central tendency and variability. Measurable evidence shall demonstrate that these control
29、s are effective. 3.3.3 When option 3.3.1.a is used, appropriate control limits and rules shall be in place to separate common cause from special cause variation. Such limits shall be based on variability inherent to the process, and not influenced by product requirements such as engineering toleranc
30、es. See Figure 1. See Appendix A for guidance. Control limits or other process stability criteria shall be based on process measurements taken under one of the following conditions: When the process is operating under stable conditions including sources of variation inherent in routine production. U
31、nder conditions shown in 3.3.3.a with variation uncharacteristic of routine production (e.g., process set-up, outliers) removed from the calculations. SAE ARP9013/3 - 6 - FIGURE 1 - Typical Control Chart Depicting Control Limits and Warning Zones 3.3.3 (Continued): NOTE: For cases where the process
32、capability exceeds product requirements, control limits may be set wider than three-sigma. However, when using SPC to accept product it shall be demonstrated that controlling to these wider limits does not allow acceptance of non-conforming product. 3.3.4 When one point falls beyond Zone A (see Figu
33、re 1), special causes of variation shall be investigated. The out-of-control point shall be annotated on the control chart, and any corrective action recorded. If after thorough investigation of the process no special cause of variation can be found, the process may be treated as having had a false
34、alarm. Out of control points shall not be designated as false alarms more frequently than can be explained through random chance. See Appendix A for guidance on the level of investigations. 3.3.5 If the process gives evidence of violating statistical stability, product acceptance by process control
35、methods shall be suspended and an alternative method of product verification shall be employed until stability is revalidated. 3.3.6 Stability measures, such as control limits, limits on first/last piece, etc., shall be re-evaluated whenever identified changes are made to the process. When such limi
36、ts are modified, the associated capability measure shall also be recalculated. 3.4 Capability: A measure of process capability shall only be valid for data taken when the process shows adequate statistical stability. 3.4.1 If not otherwise specified by engineering drawings, specifications, or other
37、design documentation, the data shall provide 90% confidence that the process capability is within the engineering tolerance. See Table 1. If only one specification limit exists, the data shall provide 90% confidence that the process capability is on the acceptable side of that limit. Statistically v
38、alid capability measures (Cpk, Ppk, etc.) shall be used. Capability calculations shall include all data used in demonstrating statistical stability (see 3.3.1). SAE ARP9013/3 - 7 - 3.4.2 If the characteristic is not capable, the organization shall identify and control sources of variation in the pro
39、cesses that are correlated with the characteristic and take corrective action. These investigation findings and corrective actions shall be documented. If the process does not meet minimum capability requirements, an approved acceptance sampling plan or 100% inspection shall be enacted until the cau
40、se has been identified and capability revalidated. TABLE 1 - True Cpk Requirements 90% probability that true Cpk equals or exceeds: Number of measurements taken 1.00 1.10 1.20 1.30 1.40 1.50 1.60 1.70 1.80 1.90 2.00 250 1.07 1.17 1.28 1.42 1.49 1.60 1.70 1.81 1.91 2.02 2.13 200 1.08 1.18 1.29 1.43 1
41、.50 1.61 1.72 1.82 1.93 2.04 2.14 150 1.09 1.20 1.30 1.44 1.52 1.63 1.74 1.84 1.95 2.06 2.17 125 1.10 1.21 1.32 1.45 1.53 1.64 1.75 1.86 1.97 2.08 2.18 100 1.11 1.22 1.33 1.47 1.55 1.66 1.77 1.88 1.99 2.10 2.21 90 1.12 1.23 1.34 1.48 1.56 1.67 1.78 1.89 2.00 2.11 2.22 80 1.13 1.24 1.35 1.49 1.57 1.6
42、8 1.79 1.90 2.02 2.13 2.24 70 1.14 1.25 1.36 1.50 1.58 1.70 1.81 1.92 2.03 2.14 2.26 60 1.15 1.26 1.38 1.52 1.60 1.71 1.83 1.94 2.06 2.17 2.28 50 1.17 1.28 1.40 1.54 1.63 1.74 1.85 1.97 2.08 2.20 2.31 46 1.18 1.29 1.41 1.55 1.64 1.75 1.87 1.98 2.10 2.21 2.33 42 1.19 1.30 1.42 1.56 1.65 1.77 1.88 2.0
43、0 2.12 2.23 2.35 38 1.20 1.31 1.43 1.58 1.67 1.78 1.90 2.02 2.14 2.25 2.37 34 1.21 1.33 1.45 1.60 1.68 1.80 1.92 2.04 2.16 2.28 2.40 30 1.23 1.35 1.47 1.62 1.71 1.83 1.95 2.07 2.19 2.31 2.43 28 1.24 1.36 1.48 1.63 1.72 1.84 1.97 2.09 2.21 2.33 2.45 26 1.25 1.37 1.49 1.65 1.74 1.86 1.98 2.11 2.23 2.3
44、5 2.47 24 1.26 1.39 1.51 1.66 1.76 1.88 2.00 2.13 2.25 2.38 2.50 22 1.28 1.40 1.53 1.68 1.78 1.90 2.03 2.15 2.28 2.40 2.53 20 1.30 1.42 1.55 1.71 1.80 1.93 2.06 2.18 2.31 2.44 2.57 The values in the body of the table are the calculated Cpk values required to be 90% confident that the actual Cpk is g
45、reater than or equal to the Cpk value at the top of the respective column. The values listed in the column titled “Number of measurements taken“ are the actual number of measured characteristic values, not necessarily the number of plot points. Table calculations assume measurements are normally dis
46、tributed. See Appendix B for further guidance on use of this table. SAE ARP9013/3 - 8 - 3.5 Process Monitoring Frequency: The process monitoring frequency shall be often enough so that at least one observation is taken before affected products leave the immediate process area. The “immediate process
47、 area” shall be restricted to the property of the subject organization. The process monitoring frequency shall also be able to detect any process shifts or trends in a manner timely enough to recover all untested or unmeasured product produced since the previous in-control point. This frequency shal
48、l be documented in the applicable Process Control Acceptance Plan. 3.6 Recall System: The organization shall have the ability to retrieve all products, including any untested or unmeasured products that are deemed suspect. Traceability of the products shall be tied to the process control system, tha
49、t is, points that are unstable shall be included in the quality record associated with products manufactured while the process was unstable. 3.7 Limiting Measurement and Recording Errors: See AS9100 and ARP9013 for requirements. See Appendix A for guidance. 3.8 Evaluating Effects of Corrective Actions: Corrective actions shall be evaluated to determine the effect on the characteristics being accepted by the process control plan. A process control plan shall avoid tampering, that is, changing a process without statistically valid indications of a process shift. 3.9 Correlation S
