ISO 3951-3-2007 计量检验的抽样程序.第3部分:按接收质量限(AQL)检索的逐批检验二次抽样计划

标准号：ISO 3951-3-2007
中文标准名称：计量检验的抽样程序.第3部分:按接收质量限(AQL)检索的逐批检验二次抽样计划
英文标准名称：Sampling procedures for inspection by variables - Part 3: Double sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot inspection
标准类型：A41
发布日期：1999/12/31 12:00:00
实施日期：1999/12/31 12:00:00
中国标准分类号：A41
国际标准分类号：03.120.30
适用范围：This part of ISO 3951 specifies an acceptance sampling system of double sampling schemes for inspection byvariables for percent nonconforming. It is indexed in terms of the acceptance quality limit (AQL).The objectives of the methods laid down in this part of ISO 3951 are to ensure that lots of acceptable qualityhave a high probability of acceptance and that the probability of non-accepting inferior lots is as high aspracticable. This is achieved by means of the switching rules, which provide⎯ automatic protection to the consumer (by means of a switch to tightened inspection or discontinuation ofsampling inspection) should a deterioration in quality be detected, and⎯ an incentive (at the discretion of the responsible authority) to reduce inspection costs (by means of aswitch to a smaller sample size) should consistently good quality be achieved.In this part of ISO 3951, the acceptability of a lot is implicitly or explicitly determined from an estimate of thepercentage of nonconforming items in the process, based on either one or two random samples of items fromthe lot.This part of ISO 3951 is primarily designed for use under the following conditions:a) where the inspection procedure is to be applied to a continuing series of lots of discrete products allsupplied by one producer using one production process; if there are different producers or productionprocesses, apply this part of ISO 3951 to each one separately;b) where the items of product have a single quality characteristic (for multiple quality characteristics, seeinformative Annexes A, B and C);c) where the quality characteristic is measurable on a continuous scale;d) where the measurement error is negligible (i.e. with a standard deviation of no more than 10 % of thecorresponding process standard deviation);e) where production is stable (under statistical control) and the quality characteristic is distributed, at least toa close approximation, according to a normal distribution;CAUTION — The procedures in this part of ISO 3951 are not suitable for application to lots that havebeen screened previously for nonconforming items.f) where the possibility of having to select and inspect a second sample is administratively acceptable;