標準號：ISO 3951-3-2007
中文標準名稱：計量檢驗的抽樣程序.第3部分:按接收質量限(AQL)檢索的逐批檢驗二次抽樣計劃
英文標準名稱：Sampling procedures for inspection by variables - Part 3: Double sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot inspection
標準類型：A41
發布日期：1999/12/31 12:00:00
實施日期：1999/12/31 12:00:00
中國標準分類號：A41
國際標準分類號：03.120.30
適用范圍：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;