1、_ 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 its applicability and suitability for any particular use, including any patent infringement arising there
2、from, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2014 SAE International All rights reserved. No part of this p
3、ublication 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 SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-497
4、0 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/AS5870AEROSPACESTANDARDAS5870Issued 2010-01 Reaffirmed 2014-10 Thread Inspection
5、Practices RATIONALE AS5870 has been reaffirmed to comply with the SAE five-year review policy. TABLE OF CONTENTS 1. SCOPE 3 2. REFERENCES 3 3. GAGE SELECTION AND USE . 6 4. SINGLE ELEMENT PITCH DIAMETER PRODUCT ACCEPTANCE LIMITS AND GUARDBAND FACTORS 12 5. NOTES 25 APPENDIX A PRODUCT DISTRIBUTIONS A
6、ND CONSUMER RISK . 26 FIGURE 1 MEASUREMENT SYSTEM FLOW CHART . 7 FIGURE 2 EXAMPLE OF A BIASED PRODUCT DISTRIBUTION WITH A BIAS IN THE MEASUREMENT SYSTEM 10 TABLE 1 THREAD GAGING FOR EXTERNAL THREAD PRODUCT 8 TABLE 2 THREAD GAGING FOR INTERNAL THREAD PRODUCT (NOTE 1) . 9 TABLE 3 GUARDBAND FACTORS AND
7、 INSPECTION LIMITS FOR EXTERNAL THREAD UNJ COARSE SERIES PRODUCT 13 TABLE 4 GUARDBAND FACTORS AND INSPECTION LIMITS FOR INTERNAL THREAD UNJ COARSE SERIES PRODUCT 14 TABLE 5 GUARDBAND FACTORS AND INSPECTION LIMITS FOR EXTERNAL THREAD UNJ FINE SERIES PRODUCT . 15 TABLE 6 GUARDBAND FACTORS AND INSPECTI
8、ON LIMITS FOR INTERNAL THREAD UNJ FINE SERIES PRODUCT . 16 TABLE 7 GUARDBAND FACTORS AND INSPECTION LIMITS FOR EXTERNAL THREAD UNJ EXTRA FINE SERIES PRODUCT 17 TABLE 8 GUARDBAND FACTORS AND INSPECTION LIMITS FOR INTERNAL THREAD UNJ EXTRA FINE SERIES PRODUCT 18 TABLE 9 GUARDBAND FACTORS AND INSPECTIO
9、N LIMITS FOR EXTERNAL THREAD UNJ EIGHT THREAD SERIES PRODUCT 19 TABLE 10 GUARDBAND FACTORS AND INSPECTION LIMITS FOR INTERNAL THREAD UNJ EIGHT THREAD SERIES PRODUCT 20 TABLE 11 GUARDBAND FACTORS AND INSPECTION LIMITS FOR EXTERNAL THREAD UNJ TWELVE THREAD SERIES PRODUCT 21 TABLE 12 GUARDBAND FACTORS
10、AND INSPECTION LIMITS FOR INTERNAL THREAD UNJ TWELVE THREAD SERIES PRODUCT 22 TABLE 13 GUARDBAND FACTORS AND INSPECTION LIMITS FOR EXTERNAL THREAD UNJ SIXTEEN THREAD SERIES PRODUCT 23 TABLE 14 GUARDBAND FACTORS AND INSPECTION LIMITS FOR INTERNAL THREAD UNJ SIXTEEN THREAD SERIES PRODUCT 24 SAE INTERN
11、ATIONAL AS5870 2 OF 271. SCOPE This document addresses AS8879 thread inspection issues relating to selection, usage and capability of gages. It addresses the selection of calibrated measurement gages, the need for defined quality metrics, the methodology of determining the appropriate guardband fact
12、ors, and the minimum inspection requirements for single element pitch diameter gages. Users of this document shall apply the information described herein for the evaluation of the capability of their measurements based on the measurement consumer risk. It involves the analysis of the measurement (pr
13、oduct) distribution and biases of both the product and measurement system distributions. It protects the consumer from the worst case distribution results. A whitepaper has been developed to provide supporting documentation and the rationale used in the development of this standard. This whitepaper
14、will be published by the SAE as an Aerospace Information Report (AIR6553). This document recommends the use of ASME B1.2 “Gages and Gaging for Unified Inch Screw Threads” or IFI 301 “Gage Calibration Requirements and Procedures for Thread Gages” as guides for establishing the minimum calibration req
15、uirements for all types of thread gages. 2. REFERENCES 2.1 Applicable Documents The following publications form a part of this document 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 dat
16、e of the purchase order. In the event of conflict between the text of this document and references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained 2.1.1 SAE Publicati
17、ons Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org. AIR6553 Measurement Uncertainty and Consumer Risk AS8879 Screw Threads - UNJ Profile, Inch, Controlled Radius Root with Incre
18、ased Minor Diameter ARP9013 Statistical Product Acceptance Requirements 2.1.2 ASME Publications Available from American Society of Mechanical Engineers, 22 Law Drive, P.O. Box 2900, Fairfield, NJ 07007-2900, Tel: 973-882-1170, www.asme.org. ASME B1 Technical Report “Measurement Uncertainty for 60 de
19、gree Screw Thread Gage Element Measurement Inch and Metric” ASME B1.2 Gages and Gaging for Unified Inch Screw Threads ASME B1.3 Screw Thread Gaging System for Dimensional Acceptability - Inch and Metric Screw Threads (UN, UNR, UNJ, M, and MJ) ASME B89.7.4.1 Measurement Uncertainty and Conformance Te
20、sting: Risk Analysis SAE INTERNATIONAL AS5870 3 OF 272.1.3 FAA Publications Available from Federal Aviation Administration, 800 Independence Avenue, SW, Washington, DC 20591, Tel: 866-835-5322, www.faa.gov. REPORT NO: FAA-IR-01-02 - AVIATION FASTENER AUDIT FINAL REPORT JUNE 13, 2001 Available at: ww
21、w.faa.gov/library/reports/media/FASTENER_AUDIT_REPORT.pdf 2.1.4 Industrial Fastener Institute Publications Available from Industrial Fastener Institute, 6363 Oak Tree Boulevard, Independence, Ohio 44131, Tel: 216-241-1482, www.indfast.org. IFI 301 Gage Calibration Requirements and Procedures for Thr
22、ead Gages 2.2 DEFINITIONS 2.2.1 Average Outgoing Quality Limit (AOQL) Maximum average outgoing quality over all possible values of incoming product quality level for a given acceptance sampling plan. 2.2.2 Average Outgoing Quality (AOQ) The average quality of outgoing product after sampling inspecti
23、on for a given steady value of incoming product quality. 2.2.3 Confidence Interval (CI) The interval of a measurement result that is estimated to contain an associated percentage, as represented by the confidence level, of the distribution of possible measurement results, e.g., 0.0002 inch. 2.2.4 Co
24、nfidence Level (CL) The probability that a measurement result made at the time of its evaluation is within its associated confidence interval. 2.2.5 Consumer Risk (CR) (single measurand) A numerical estimate of the probability that the true value of a measurand (for example: pitch diameter at 68 F)
25、falls outside a given performance specification, but is measured to be within the guardband limit. 2.2.6 Error Ratio (ER) The ratio between the engineering tolerance and the Measurement System Error for a given measurement on the same confidence level basis. 2.2.7 Expanded Error The sum of the measu
26、rand bias and extended uncertainty that bound the values of expected error for a given confidence level. SAE INTERNATIONAL AS5870 4 OF 272.2.8 Expanded Uncertainty The lower and/or upper confidence intervals that bound the expected values of a random variable for a given confidence level. 2.2.9 Guar
27、dband Limit (GBL) Reduced acceptance limit that maintains the target measurement consumer risk NOTE 1: Guardband limit, as defined here, is risk-based and is therefore consistent with the general basis of this standard. NOTE 2: These limits are obtained by multiplying the Guardband Factor (GBF) time
28、s the Product Tolerance. 2.2.10 Initial Reliability Requirement (IRR) The minimum probability of product conformance which the inspection procedure allows. This is an index used in defining reliability-based sampling plans. 2.2.11 Measurement Capability The performance of a measurement system as int
29、ended to define, realize, conserve or reproduce one or more of its obtained measurement values. 2.2.12 Producer Risk (PR) A numerical estimate of the probability that the true value of a measurand (for example: pitch diameter at a known temperature) falls inside a given performance specification, bu
30、t is measured to be outside the guardband limit. 2.2.13 Quality Metric Parameter used to define a sampling requirement, (e.g., AOQL). 2.2.14 Rejectable Quality Level (RQL) The minimum percent defective at which a lot will have 5% or less chance of being accepted when using a sampling plan or another
31、 statistically based monitoring system. 2.2.15 Sigma Model The performance specification divided by the number of standard deviations in the product distribution. 2.2.16 Uncertainty Ratio (UR) The Historical Measurand Expanded Uncertainty of the product divided by the Measurement System Expanded Unc
32、ertainty for a given measurement on the same confidence level basis (for example, both 2 sigma). SAE INTERNATIONAL AS5870 5 OF 273. GAGE SELECTION AND USE 3.1 Requirements 3.1.1 Applicability Thread inspection gages shall be used in accordance with the requirements of this standard to ensure conform
33、ance to customer design documents, contracts and legal or regulatory requirements. As allowed for in ASME B89.7.4.1, and for the purpose of this document, risk-based guardbanding is the chosen basis for ensuring a measurement process is consistent with the required measurement capability. Risk based
34、 guardbands ensure that the maximum acceptable level of consumer risk is not exceeded when determining the guardband factors based on Error or Uncertainty Ratios. ASME B89.7.4.1 establishes the boundaries of the acceptance zone based on consumer risk but does not deal with product or measurement sys
35、tem biases as this document does. Consumer risk, known as the probability of a false accept and formally defined in 2.2.5, can be considered a measure of customer quality risk. Producer risk, known as the probability of a false reject and formally defined in 2.2.12, can be considered a measure of su
36、pplier cost risk. All other factors being equal, consumer risk is inversely related to producer risk as a function of guardband factor. Reducing the guardband factor has the effect of decreasing consumer risk and increasing producer risk. Bilateral evaluations utilize risk-based guardbanding. Attrib
37、ute gage evaluations satisfy the capability requirement by limiting consumer risk through proper design practice and consumer risk calibration methodology. The following flow chart (Figure 1) depicts the measurement system for thread measurements as defined in this document. 3.1.2 Measurement requir
38、ements shall be determined from procurement specifications, engineering definition or tabulated tolerances specified in screw thread definition documents, such as AS8879. 3.1.3 The measurement procedures and gage setting intervals to be used shall be documented. The variable gage used for product co
39、nformity determination shall be set with the set master immediately before initiating inspection of a product lot and verified immediately after product lot inspection. 3.1.4 Gages, setting masters and product to be inspected shall be stabilized under the same environmental conditions. The stabiliza
40、tion period depends on the material and size of the product and gages. 3.2 Selection of Gage(s) This process applies to measurements produced using inspection gages with traceable calibrations. This section defines the process for interpreting an inspection requirement and selecting a capable thread
41、 inspection gage. 3.2.1 Users of this process shall select thread inspection gage(s) with the capability to meet the requirements of this process. AS8879 conformance requirements and ASME B1.3 thread characteristics are referenced in Table 1 for external threads and Table 2 for internal threads. The
42、 use of any gage or inspection device is allowed as long as the gage or inspection device is shown to be capable per the requirements of this document (see 3.3). 3.2.2 Thread measurement gage(s) shall be selected for a given characteristic such that the guardband factors for the determined Error Rat
43、io are based on Table 3 through Table 14 of this document. The formulas used to calculate the values in Tables 3 through 14 are located in Appendix A. SAE INTERNATIONAL AS5870 6 OF 27An Engineering Requirement To Conform Product at an Acceptable Reliability Level The Acceptable Reliability Level Def
44、ines Acceptable Level of Measurement Consumer Risk and Associated Measurement Guardband Factors. If the Consumer Risk, both sampling and measurement, is 1 Minus the Acceptable Reliability Level then the Measurement is Capable. NOTE: Block 1 defines the measurement requirements and the acceptable cap
45、ability of the measurement based on the engineering reliability requirement (Acceptable Risk). Based on the requirement of Block 1, and for the purpose of this document, Block 2 defines the acceptable consumer risk of sampling and the measurement. These, in turn, define the required consumer based g
46、uardband factors. Knowing the consumer based guardbands allows the user to define capable measurements. FIGURE 1 - MEASUREMENT SYSTEM FLOW CHART SAE INTERNATIONAL AS5870 7 OF 273.2.3 If control of lead and flank angle variation is required for threaded product (e.g., Category 2 threads), use of the
47、variable indicating differential method is approved when full form segment gage elements are used (see Table 1, Note 3 and Table 2, Note 4). Lead and flank angle may also be measured by direct methods. TABLE 1 - THREAD GAGING FOR EXTERNAL THREAD PRODUCT Characteristic Category 1 Category 2 Ref. Colu
48、mns Table 1 in ASME B1.3 Major Diameter Major Diameter shall be within specified dimensional requirements J1 or J2 Pitch Diameter Size (Pitch Diameter or Groove Diameter) shall be within the specified dimensional requirements C2 or D2 Note: Unless otherwise specified, for products with thread length
49、 less than 6 pitches (including incomplete threads), NOT GO Functional Diameter Limit Inspection is acceptable. B1 Functional Diameter The Functional Diameter shall be less than or equal to the envelope of perfect form at Maximum Pitch Diameter A1 or A2 Note1 Minor Diameter Minor Diameter shall be within the specified dimensional requirements K1 or K2 Root Radius Root Radius shall be within the specified dimensional requirements L Incom
