1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA
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3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. ISBN 978-0-626-23480-5 SANS 14560:2009Edition 1 ISO 14560:2004Edition 1 SOUTH AFRICAN NATIONAL STANDARD Acceptance sampling procedures by attributes Spec
4、ified quality levels in nonconforming items per million This national standard is the identical implementation of ISO 14560:2004 and is adopted with the permission of the International Organization for Standardization. Published by SABS Standards Division 1 Dr Lategan Road Groenkloof Private Bag X19
5、1 Pretoria 0001Tel: +27 12 428 7911 Fax: +27 12 344 1568 www.sabs.co.za SABS SANS 14560:2009 Edition 1 ISO 14560:2004 Edition 1 Table of changes Change No. Date Scope National foreword This South African standard was approved by National Committee SABS TC 169, Applications of statistical methods, in
6、 accordance with procedures of the SABS Standards Division, in compliance with annex 3 of the WTO/TBT agreement. This SANS document was published in September 2009. Reference numberISO 14560:2004(E)ISO 2004INTERNATIONAL STANDARD ISO14560First edition2004-08-15Corrected version2004-11-01Acceptance sa
7、mpling procedures by attributes Specified quality levels in nonconforming items per million Rgles dchantillonnage par attributs en vue dacceptation Niveaux spcifis de qualit en termes dindividus non conformes pour un million dindividus SANS 14560:2009This s tandard may only be used and printed by ap
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13、4560:2009This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO 14560:2004(E) ISO 2004 All rights reserved iiiContents Page Foreword iv Introduction.v 1 Scope1 2 Normative references1 3 Terms, definitions, symbols and abbreviated terms .1 4 Gene
14、ral principles .2 4.1 Objective 2 4.2 Quality assessment of product2 4.3 Acceptance sampling of a lot.2 5 Estimation of quality levels in nonconforming items per million items3 5.1 Prerequisites3 5.2 Data sources3 5.3 Estimation of pM, the process quality level 3 5.4 Sampling requirements and guidel
15、ines 4 5.5 Examples of estimation of the quality level4 5.6 Reporting results.5 6 Lot acceptance sampling requirements and procedures .6 6.1 Overview.6 6.2 Requirements and guidelines 6 6.3 Lot acceptance procedure7 6.4 Illustrated use of Table 1 7 7 Single sampling plans indexed by LQL in nonconfor
16、ming items per million items 8 Annex A (normative) Data exclusion 12 Annex B (informative) Underlying theory for generating point estimates of quality level in fraction nonconforming 15 Annex C (informative) Statistical theory and calculation of Table 1 .17 Bibliography19 SANS 14560:2009This s tanda
17、rd may only be used and printed by approved subscription and freemailing clients of the SABS .ISO 14560:2004(E) iv ISO 2004 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of pre
18、paring International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in
19、 liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task
20、 of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention
21、 is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 14560 was prepared by Technical Committee ISO/TC 69, Applications of statistical methods, Subcommittee SC
22、5, Acceptance sampling. This corrected version of ISO 14560:2004 incorporates the following correction: in Annex C the maximum consumers risk has been corrected to 21 %. SANS 14560:2009This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO 14560
23、:2004(E) ISO 2004 All rights reserved vIntroduction For processes that produce nonconforming items relatively rarely, it is advantageous to replace traditional methods of estimating and reporting quality levels by more suitable methods. For example, an estimated outgoing quality level reported as 10
24、 nonconforming items per million items carries a more immediately comprehensible message than either 0,00001 nonconforming items per item or 0,001 nonconforming items per 100 items. This International Standard provides alternative methods that use nonconforming items per million items terminology in
25、 estimating and reporting quality levels. This International Standard provides a means by which quality requirements, stated to be no worse than a given number of nonconforming items per million items, can be verified on a lot-by-lot basis. Procedures are also provided for estimation of the process
26、quality level based on evidence from previous audit and/or lot acceptance samples. Additionally, guidance is given for presuming a process quality level so that the verification procedure can be used when prior sample data is inadequate or not available. A key feature of this International Standard
27、is that it provides incentives for suppliers to improve their quality. The lot acceptance portion of this specification requires larger sample sizes when quality declines, smaller sample sizes when quality improves. If a customer specifies the same quality requirements to multiple suppliers of a pro
28、duct, those suppliers with superior quality will require, on average, smaller samples for acceptance sampling. This document is based upon the US Electronic Industries Alliance standards EIA-554 and EIA-555, which it consolidates and reorients to indicate that the procedures are generic and can ther
29、efore also be used in industrial or service applications not generally serviced by EIA. SANS 14560:2009This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .SANS 14560:2009This s tandard may only be used and printed by approved subscription and fre
30、emailing clients of the SABS .INTERNATIONAL STANDARD ISO 14560:2004(E) ISO 2004 All rights reserved 1Acceptance sampling procedures by attributes Specified quality levels in nonconforming items per million 1 Scope This International Standard specifies, for quality levels expressed as nonconforming i
31、tems per million items, procedures for estimating the quality level of a single entity (e.g. a lot) and, when the production process is in statistical control, for estimating the process quality level based on evidence from several samples. Procedures are also specified for using this information wh
32、en selecting a suitable sampling plan so as to verify that the quality level of a given lot does not exceed a stated limiting quality level (LQL). For the case where no prior sample data is available, guidance is given for presuming a process quality level in selecting a plan. 2 Normative references
33、 The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 2859-1, Sampling procedures for inspection b
34、y attributes Part 1: Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot inspection ISO 3534-1, Statistics Vocabulary and symbols Part 1: Probability and general statistical terms ISO 3534-2, Statistics Vocabulary and symbols Part 2: Statistical quality control 3 Terms, definit
35、ions, symbols and abbreviated terms For the purposes of this document, the terms and definitions given in ISO 2859-1, ISO 3534-1 and ISO 3534-2, and the following symbols and abbreviated terms apply. Ac acceptance number, representing the largest number of nonconforming items found in the sample tha
36、t permits the acceptance of the lot, as given in the sampling plan d number of nonconforming items observed dinumber of nonconforming items found in the sample from the ith lot LQL limiting quality level, in nonconforming items per million items (i.e. the actual quality level of a lot that correspon
37、ds to a probability of 21 % or less of lot acceptance for the sampling plan used) LPlower limit to the assessed process quality level for a given LQL and Ac, used for selecting a plan from Table 1 NOTE 1 LPis the lowest actual quality level of a lot for which the probability of lot acceptance is 90
38、% or more for a sampling plan with the given acceptance number, but which is less than 90% for a sampling plan with the next smaller acceptance number for the same LQL. SANS 14560:2009This s tandard may only be used and printed by approved subscription and freemailing clients of the SABS .ISO 14560:
39、2004(E) 2 ISO 2004 All rights reservedm total number of lots that are subjected to inspection n number of items sampled from a lot ninumber of items sampled from the ith lot p quality level in fraction nonconforming items p estimator of p pMquality level in nonconforming items per million items, pM=
40、 p 106Mp estimator of pMP1,Mproducers risk quality level in nonconforming items per million items (i.e. the quality level that corresponds to a probability of lot rejection of 5 %) P2,Mconsumers risk quality level in nonconforming items per million items (i.e. the quality level that corresponds to a
41、 probability of lot acceptance of 10 %) UPupper limit to the assessed process quality level for a given LQL and Ac, used for selecting a plan from Table 1 NOTE 2 UPis the highest actual quality level of a lot for which the probability of lot acceptance is 90 % or more for the sampling plan used. 4 G
42、eneral principles 4.1 Objective The objective of this International Standard is twofold: the quality assessment of product and the acceptance sampling of a lot when quality is high, as indicated by the fact that it is typically expressed in terms of numbers of nonconforming items per million items.
43、4.2 Quality assessment of product It is assumed that the product has been through its manufacture, inspection, test and final acceptance procedures, including procedures for eliminating unrepresentative lots. When sampling from a consecutive series of lots, the assessment procedures in this Internat
44、ional Standard are applicable when a) the production process is in statistical control, and b) the cumulative number of inspected items (audit and/or lot acceptance items) is 400 or more. 4.3 Acceptance sampling of a lot Sampling procedures are provided to verify that the quality is no worse than th
45、e limiting quality level (LQL). An estimate of the process quality level in nonconforming items per million items, based on previous data, is used to select the appropriate sampling plan. Presumption (rather than estimation) of the process quality level is permitted when determining sampling plans f
46、or the first few lots in a series or for isolated lots, unless and until enough data is available to form a valid estimate. It is recommended that estimation of the process quality level commence when the total number of inspected items (audit and/or lot acceptance items) from one or more consecutiv
47、e lots is 400 or more; otherwise, continue to presume the process quality level (see 6.1). The sampling plans in this International Standard are indexed by the LQL and the estimated (or presumed) process quality level. SANS 14560:2009This s tandard may only be used and printed by approved subscripti
48、on and freemailing clients of the SABS .ISO 14560:2004(E) ISO 2004 All rights reserved 3Suppliers are encouraged to not only drive their processes to a state of statistical control, but also to employ continuous improvement techniques to raise the quality of their products. As quality levels improve
49、, suppliers can then benefit from this International Standards provision for reduction in acceptance sample size. Acceptance sampling procedures given in this International Standard can be used when processes have actual nonconforming quality levels of up to 37 606 nonconforming items per million items. However, selecting a small LQL may result in a prohibitively large sample size (see Table 1). For large LQLs, existing sampling plans in other international standards (e.g. ISO 2859-1) may be more appropriate depending u
