GB/T 6378.3-2024Sampling procedures for inspection by variables - Part 3: Double sampling schemes indexed by acceptance quality limit (AQL)for lot-by-lot inspection (English PDF)

Foreword

This document is in accordance with the provisions of GB/T 1.1-2020 "Guidelines for standardization work Part 1: Structure and drafting rules for standardization documents" Drafting.

This document is part 3 of GB/T 6378 "Measurement sampling inspection procedures". GB/T 6378 has been published in the following parts.

--- Part 1: Single sampling for batch inspection of a single quality characteristic and a single AQL indexed by acceptance quality limit (AQL) plan;

--- Part 3: Secondary sampling plan for batch inspection based on acceptance quality limit (AQL);

--- Part 4: Procedure for assessing the claimed quality level of the mean;

--- Part 7: Procedure for assessing the claimed quality level for the nonconforming rate.

This document is modified to adopt ISO 3951-3:2007 "Sampling procedures for measurement - Part 3: Sampling procedures based on acceptance quality limit (AQL)" "Subsampling Plan for Batch Inspection".

The technical differences between this document and ISO 3951-3:2007 and their reasons are as follows.

--- Added the definition of term 3.30 "indistinguishable point". The concept of indistinguishable point is mentioned in the standard, but there is no corresponding term explanation;

--- Changed the normative references in Chapter 2, replacing ISO 3534-1 with undated GB/T 3358.1;

--- Changed "for example. R1" in 8.4 operating characteristic curve to "for example. T1, T2,, R1, R2", which is consistent with the previous sentence the two letters T or R in the table correspond to the actual table;

--- Added the corresponding scheme when the sample size code is L and the receiving quality limit is 0.1 in Table 24, which is missing in the original text;

--- Changed the nature of the appendices in the document, and all normative appendices were adjusted to informative appendices.

The following editorial changes were made to this document.

--- Deleted "as shown in 10d) above" in the selection of method 11, the original text is wrong;

--- Changed "dsigma" in 17.1 Retrieval plan, sampling and preliminary calculation to "sigmamax", the original text is wrong;

--- Changed the value of the mean xL,1 of the first sample lower specification limit in Table 3, "500.79" to "500.81"; the first sample lower specification limit the value of the standard deviation sL,1 of "2.669" is changed to "2.2403", and the value of the lower specification limit quality statistic QL,1=(xL,1-L)/sL,1 is changed to "2.5541" is changed to "2.5934", the value of the mean of the upper specification limit of the first sample xU,1 is changed from "500.25" to "500.27", and the first sample the value of the standard deviation sU,1 of the upper specification limit is changed from "2.4567" to "2.4407", and the quality statistic QU,1 of the upper specification limit is changed from (U-the value of xU,1)/sU,1 "1.9335" was changed to "1.9380", which was wrong in the original text;

--- Changed the calculation of the lower limit of step f in E.5 of Table 6, "wLIntroduction the metrological inspection with the percentage of nonconforming products as the quality indicator in this document includes several modes, the possible combinations of which are more convenient for users.

For complexity.

a) a procedure when the process standard deviation is unknown (method S), or a procedure when the process standard deviation is initially unknown but can be estimated with reasonable accuracy, or Procedure when the process standard deviation is known at the beginning of the test (sigma method);

b) One-sided specification limits, two-sided specification limits for combined, separate or composite controls;

c) normal inspection, stricter inspection or relaxed inspection;

d) k criterion and p* criterion;

e) A single quality characteristic (in the case of a single variable) or multiple independent quality characteristics (in the case of multiple independent variables).

By using this document, simpler procedures can be implemented without understanding complex procedures. The body of this document is limited to a single variable the s-method procedure, sigma-method procedure, and combined s-method and sigma-method procedure for multiple independent variables are listed in Appendix A, Appendix B, Appendix C gives the corresponding terms and diagrams of this document that users need to use in different possible situations of a single variable.

Although Annex D is only relevant to the contents of Chapters 16, 17, 21, 22 and 23, it is in any case, you should read Chapters 1 to 15 and 18 to 20 first.

GB/T 6378 "Measurement Sampling Inspection Procedure" series of standards are basic general standards for measurement sampling inspection, which are divided into the following Seven parts.

--- Part 1: Single sampling for batch inspection of a single quality characteristic and a single AQL retrieved by acceptance quality limit (AQL) Scheme (GB/T 6378.1-2008). It is intended to specify the acceptance sampling system for the measurement single sampling inspection plan, which is based on the acceptance of quality the purpose of the method given in this part of ISO 14001 is to ensure that the actual quality level is better than the acceptance quality limit.

The batch is accepted with a high probability, while ensuring that the batches with actual quality levels worse than the acceptance quality limit are accepted with a low probability.

--- Part 2: General rules for a single sampling plan for batch inspection of independent quality characteristics indexed by acceptance quality limit (AQL) it is intended to give a more general technical treatment of lot-by-lot variable sampling for independent quality characteristics.

In the acceptance sampling system that specifies the measurement secondary sampling inspection plan, the secondary sampling inspection plan in this part is Supplement to GB/T 6378.1.

--- Part 4: Procedure for assessing the claimed quality level of the mean (GB/T 6378.4-2018). Aims to specify the procedure for assessing the claimed quality level of the mean.

The average value of a certain quality characteristic of a body is a quantitative sampling inspection procedure for quality indicators, which is applicable to various forms of quality verification.

This part is the GB/T 6378 series of documents for the assessment procedures of claimed quality levels.

--- Part 5: Sequential sampling plan for metrological inspection based on acceptance quality limit (AQL). Sequential sampling inspection in this part the plan is a supplement to GB/T 6378.1.

--- Part 6: Sampling plan for isolated batch inspection based on limit quality LQ. This sampling system is used for isolated batches (isolated series Batch, isolated batch or single batch) inspection, the transfer rules of GB/T 6378.1 do not apply here. The sampling plan provided in this part as a supplement to GB/T 6378.1 and compatible with GB/T 6378.1.

--- Part 7: Procedure for assessing the claimed quality level of the nonconforming product rate (GB/T 6378.7-2024). This part is for A supplement to GB/T 6378.4, which together with GB/T 6378.4 constitutes the GB/T 6378 series of documents for claiming quality levels.

Assessment procedures.

This document is a supplement to the secondary sampling plan and procedures in GB/T 2828.1.

If this document and GB/T 2828.1 are cited in the contract, inspection instructions or other documents at the same time, they are valid and the provisions specified in them shall prevail.

The responsible department is specified in these documents.

Quantitative Sampling Inspection Procedure Part 3: Retrieval by acceptance quality limit (AQL) Secondary sampling plan for batch inspection

1 Scope

This document specifies the acceptance sampling system for the measurement secondary sampling inspection plan, which uses the percentage of nonconforming products as the quality indicator and the acceptance quality as the standard.

Quantity Limit (AQL) search.

The purpose of the method given in this document is to ensure that batches with actual quality levels better than the acceptance quality limit are accepted with a high probability and to ensure Batches whose actual quality level is inferior to the acceptance quality limit are accepted with low probability. The above purpose is achieved through transfer rules. These rules are.

--- When quality deterioration is found, it is advisable to automatically provide protection to the user by transferring to stricter inspection or suspending sampling inspection;

--- If the quality is consistently good, it may be appropriate, with the agreement of the responsible authority, to reduce the inspection costs by switching to a sampling scheme with a smaller sample size.

Incentivize producers.

Lot acceptability in this document is determined essentially or explicitly by the percentage of process nonconforming items (one or more items randomly selected from each lot in the process).

Two samples to estimate).

This document is intended to be used primarily under the following conditions.

a) The inspection procedures in this document apply to continuous series of batches of discrete individual products, i.e. all products are produced by the same manufacturer and in the same production process.

If there are different manufacturers or production processes, this document shall be applied to each manufacturer or production process separately.

b) Consider a single quality characteristic of the product (for multiple quality characteristics, see Annex A, Annex B and Annex C).

c) Quality characteristics are measured using a continuous scale.

d) The measurement error is negligible (i.e. its standard deviation is no more than 10% of the process standard deviation).

e) The production process is stable (under statistical control) and the quality characteristic values follow a normal distribution or approximately follow a normal distribution.

NOTE. The procedures in this document are not applicable to batches that have been previously screened for nonconforming product.

f) It is management-acceptable that a second sample may be drawn and tested.

g) If the contract or standard specifies an upper specification limit U, a lower specification limit L, or both; if and only if the product being measured A quality characteristic x is considered to be compliant when it satisfies one of the following inequalities.

1) The quality characteristic value x >= L (i.e. not less than the lower specification limit);

2) The quality characteristic value x<=U (i.e. not higher than the upper specification limit);

3) The quality characteristic value L<=x<=U (i.e. the quality characteristic value is between the lower specification limit and the upper specification limit).

Note. Cases 1) and 2) are called one-sided specification limits, and case 3) is called two-sided specification limits.

Discrete control and compound control, as follows.

--- Joint control means that only one total acceptance quality limit AQL is specified for the two-sided specification limits;

--- Separate control means that the acceptance quality limit AQL is specified for each side of the double-sided specification limit;

---Compound control means that a larger AQL is specified for one side of the specification limit, and a larger acceptance quality is specified for both sides of the specification limit Limited to AQL.

2 Normative references

The contents of the following documents constitute essential clauses of this document through normative references in this document.

For referenced documents without a date, only the version corresponding to that date applies to this document; for referenced documents without a date, the latest version (including all amendments) applies to