NF ISO 3951-2
Sampling procedures for inspection by variables - Part 2 : general specification for single sampling plans indexed by acceptance quality limit (AQL) for lot-by-lot inspection of independent quality characteristics
ISO 3951-2:2013 specifies an acceptance sampling system of single sampling plans for inspection by variables. It is indexed in terms of the acceptance quality limit (AQL) and is of a technical nature, aimed at users who are already familiar with sampling by variables or who have complicated requirements. (A more introductory treatment is given in ISO 3951-1.) The objectives of the methods laid down in ISO 3951-2:2013 are to ensure that lots of an acceptable quality have a high probability of acceptance and that the probability of not accepting inferior lots is as high as practicable. This is achieved by means of the switching rules, which provide the following: automatic protection to the consumer (by means of a switch to tightened inspection or discontinuation of sampling inspection) should a deterioration in quality be detected; an incentive (at the discretion of the responsible authority) to reduce inspection costs (by means of a switch to a smaller sample size) should consistently good quality be achieved. In ISO 3951-2:2013, the acceptability of a lot is either implicitly or explicitly determined from an estimate of the percentage of nonconforming items in the process, based on a random sample of items from the lot. ISO 3951-2:2013 is intended for application to a continuing series of lots of discrete products all supplied by one producer using one production process. If there are different producers or production processes, ISO 3951-2:2013 is applied to each one separately.
ISO 3951-2:2013 specifies an acceptance sampling system of single sampling plans for inspection by variables. It is indexed in terms of the acceptance quality limit (AQL) and is of a technical nature, aimed at users who are already familiar with sampling by variables or who have complicated requirements. (A more introductory treatment is given in ISO 3951-1.)
The objectives of the methods laid down in ISO 3951-2:2013 are to ensure that lots of an acceptable quality have a high probability of acceptance and that the probability of not accepting inferior lots is as high as practicable. This is achieved by means of the switching rules, which provide the following:
- automatic protection to the consumer (by means of a switch to tightened inspection or discontinuation of sampling inspection) should a deterioration in quality be detected;
- an incentive (at the discretion of the responsible authority) to reduce inspection costs (by means of a switch to a smaller sample size) should consistently good quality be achieved.
In ISO 3951-2:2013, the acceptability of a lot is either implicitly or explicitly determined from an estimate of the percentage of nonconforming items in the process, based on a random sample of items from the lot.
ISO 3951-2:2013 is intended for application to a continuing series of lots of discrete products all supplied by one producer using one production process. If there are different producers or production processes, ISO 3951-2:2013 is applied to each one separately.
- Avant-propos
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1
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2 Références normatives
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3 Termes et définitions
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4 Symboles
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5 Limite de qualité acceptable (LQA)
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6 Règles de basculement des contrôles normaux, renforcés et réduits
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7 Relation avec l'ISO 2859-1 et l'ISO 3951-1
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8 Protection du client
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9 Prise en compte de l'incertitude de mesurage
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10 Planification
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11 Choix entre mesures et attributs
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12 Choix entre la méthode-s et la méthode-?
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13 Choix du niveau de contrôle et de la LQA
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14 Choix du plan d'échantillonnage
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15 Opérations préliminaires
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16 Procédures normalisées pour les méthodes- s uni-variées
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17 Procédures de la méthode- s multi-variée normalisée appliquée à des caractéristiques-qualité indépendantes
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18 Procédures de la méthode- ? uni-variée normalisée
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19 Procédures de la méthode-? multi-variée normalisée appliquée à des caractéristiques-qualité indépendantes
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20 Procédures normalisées pour les méthodes- s et ? multi-variées appliquées à des caractéristiques-qualité indépendantes
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21 Procédure lors d'un contrôle continu
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22 Normalité et valeurs aberrantes
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23 Enregistrements
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24 Utilisation des règles de basculement du contrôle
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25 Interruption et reprise du contrôle
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26 Basculement entre la méthode- s et la méthode-?
- Annexe A (normative) Tableau de détermination de la lettre-code d'effectif d'échantillon
- Annexe B (normative) Plans d'échantillonnage simples du formulaire k : méthode- s
- Annexe C (normative) Plans d'échantillonnage simples du formulaire k : méthode-?
- Annexe D (normative) Plans d'échantillonnage simples du formulaire p *: méthode- s
- Annexe E (normative) Plans d'échantillonnage simples du formulaire p *: méthode-?
- Annexe F (normative) Valeurs de f s pour l'écart-type maximal d'échantillon (ETME)
- Annexe G (normative) Valeurs de f ? pour l'écart-type maximal du processus (ETMP)
- Annexe H (normative) Estimation de la proportion de non-conformes d'un processus pour l'effectif d'échantillon 3: méthode- s
- Annexe I (normative) Valeurs de c U pour la limite de contrôle supérieure sur l'écart-type d'échantillon
- Annexe J (normative) Constantes d'acceptabilité supplémentaires pour le basculement vers le contrôle réduit
- Annexe K (normative) Procédures pour l'obtention de s et ?
- Annexe L (normative) Estimation de la proportion de non-conformes d'un processus
- Annexe M (informative) Qualités du risque client
- Annexe N (informative) Risques fournisseur
- Annexe O (informative) Courbes d'efficacité de la méthode-?-
- Annexe P (informative) Prise en compte de l'incertitude de mesurage
- Bibliographie
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