Some standard content:
National Standard of the People's Republic of China
Skip-lot sampling inspection procedures by attributes
1 Subject content and scope of application
1.1 Subject content
GB/T 13263-91
This standard specifies a skip-lot procedure that can reduce the number of inspections of a lot. Under this procedure, less than every batch of products is inspected. This procedure is used in conjunction with GB2828 remote inspection sampling procedures by attributes and sampling tables (applicable to inspection of consecutive lots). 1.2 Scope of application
With the consent of the supplier, this standard may be cited in procurement, technical contracts, inspection procedures or other contract documents. The "responsible department" and "inspection agency" should be indicated in the above documents. The inspection agency can be a responsible department or an agency that implements this inspection procedure on behalf of the department. This standard does not apply to the inspection of products involving personal safety. The procedures specified in this standard can be used (but not limited to) for the following inspections: a. Finished products, such as complete machines or parts; components and raw materials; intermediate products and materials: inventory supplies, service items: data or records: management procedures, these procedures are only used for continuous batch series and are not applicable to stand-alone batches. All batches in a continuous batch series are required to have similar quality. Uninspected batches have basically the same quality as the inspected batches. There are the following restrictions when using GB2828: 2: Multiple sampling plans are not used in the skip batch inspection of this standard and the requalification of existing batches after temporary interruption. b. In this The sampling scheme with acceptance number 0 is not used in the skip batch inspection and requalification after temporary interruption of skip batch in this standard. The sampling scheme with relaxed inspection is not used in the skip batch inspection and requalification after temporary interruption of skip batch in this standard. c
Note: If the batch inspection is more effective in use, it can replace the relaxed inspection (see Appendix A). 2 Reference standards
GB2828 Batch inspection Attribute sampling procedures and sampling tables (applicable to the inspection of consecutive batches) GB3358 Statistical terms and symbols
GB10111 Method of random sampling using random number pseudo-elements 3 Terminology
3.1 Remote batch inspection
Batch inspection is the inspection of a series of products submitted to batches, and samples are taken from each batch for inspection. 3.2 Skip batch inspection
Approved by the State Administration of Technical Supervision on November 11, 1991 and implemented on August 1, 1992
GB/T 13263-91
Skip inspection is an acceptance sampling procedure whereby some batches in a series of batches with a certain number of months of sampling meet the specified criteria, and then some batches in the series of batches are accepted without inspection. 3.3 Skip inspection frequency
In skip inspection, batches are randomly selected for inspection at a specified frequency, which is called the skip inspection frequency (e.g., the skip inspection frequency is 1/2. The batches inspected at this rate account for 50% of all submitted batches). 3.4 Basic continuous production
Basic continuous production refers to production at a steady production rate. To ensure the consistency of product batch quality. At least one batch of products shall be submitted within a specified production cycle agreed upon by the supplier and the responsible department. If no production cycle is specified, at least one batch of products shall be submitted every month.
Note: For other technical terms, see CGB2828 and GB3358. 4 Qualification of suppliers and products
4.1 Qualification of suppliers
a. The supplier shall have and implement rules and regulations for controlling product quality. This system shall include that the supplier shall inspect each batch of products it produces and keep records of the inspection results. b. The supplier shall establish a system that can detect and control changes in quality levels and monitor process changes that may have an adverse effect on quality.
c. The supplier's organizational structure should not undergo changes that have a negative impact on product quality. 4.2 Qualification of products
The product should have an unchanged design.
b. Products should be produced in a basically continuous production state within a period agreed upon by the responsible department of the supplier. If no period is specified, six months should be considered as a period. If production is interrupted during the sampling and evaluation period, this period should be calculated from the evaluation and resumption of production.
c. Products should be in a normal or relaxed inspection state at the level of inspection I, II or Kawakawa during the qualification evaluation period. If it is in the tightened inspection state, the product is not eligible for skip batch inspection. d. Within a certain period agreed upon by the supplier and the responsible department, the product quality should be maintained at the AQL or the best level. If no period is specified, a period of 1 month should be taken as a period. e. 10 batches or more are accepted in succession. f. 10 batches or more meet the requirements of Table 1 in succession. g. The last two batches meet the requirements of Table 2 respectively.
If secondary or multiple sampling is used, the above requirements are only valid for the first sample. Note: 1) When the cumulative details of 10 batches fail to meet the requirements of Table 1, more than 10 batches are required, see Article 5.1. 2) Second or multiple sampling is allowed during the qualification appraisal period (status 1). 4.3 Product qualification example
Suppose the products of a capacitor factory meet a, bc and d of Article 4.2. In addition, Assume that the product is inspected at an AQL of 0.65; the total sample size of 10 consecutive acceptance batches is 1400 units: 1 defective product is found in these 10 batches. Assume that 1 defective product is found in each of the samples of the two most recent batches with a sample base of 125 units. According to Article 4.2, the minimum cumulative sample size that allows 4 defective products at an AQL of 0.65 is 1306 units, which meets the requirements of Table 1; according to Table 2, the judgment number of the sample with a maximum of 125 units is 1. The requirements of Table 2 are also met. Therefore: the product is eligible for skip-batch inspection. 5 Skip-batch procedure
Products that meet the relevant qualification requirements in Articles 4.1 and 4.2 can be subject to skip-batch inspection. Figure 1 shows the structure of the skip-batch procedure, which contains three basic states:
a. State 1: Batch-by-batch inspection during qualification; GB/T 13263—91
b. State 2. Skip inspection at a certain skip inspection frequency r. State 3; Batch inspection when skip inspection is interrupted. The product inspection procedure starts from state 1, i.e. batch inspection. When the supplier and the product obtain the qualification for skip inspection, the procedure switches to state 2. The late batch inspection may be temporarily interrupted (see Article 5.5 to enter state 3. In state 3, the product can re-qualify for the existing batch inspection under relatively less stringent conditions and return to state 2 according to the procedure conversion, see Article 5.6). On the other hand, when the procedure is in state 2 or state 3, the product may also be disqualified from skip inspection. At this time, The procedure returns to state 1. If you want to continue skipping batch inspection, the product must meet all the requirements of Sections 4.1 and 4.2 again.
5.1 Determination of initial skip inspection rate
Figure 2 shows the method for determining the initial skip inspection rate. To determine this frequency, data obtained from batch inspections of 10 or more consecutive batches is required. These data include a series of records of the number of product units inspected and the number of technically qualified products or the number of technically qualified products found in each sample. When the cumulative sample size does not reach the minimum cumulative sample size given in Table 1, more than 10 batches of batch inspections are required. The permitted initial inspection frequency is 1/2, 1/3 and 1/4. If the maximum number of batches that can be skipped for inspection is less than 20, an initial skip frequency of 1/2 can be used. If no more than 20 batches are qualified for skip inspection, but one or more batches do not meet the requirements of Table 2, an initial skip frequency of 1/3 can be used. If no more than 20 batches are qualified for skip inspection and all of these batches meet the requirements of Table 2, an initial skip frequency of 1/4 can be used. The responsible department must approve the initial skip frequency used. 5.2 Examples of determining the initial skip frequency
Continuing with the example in Section 4.3, consider three situations. The first situation assumes that the product qualifies for skip inspection in the first 10 batches. The batches range from 1250 to 9500. The sample sizes of these batches are either 125 or 200, and the number of nonconforming products found in each sample is 1 or 0. These 10 batches all meet the requirements of Table 2 at an AQL of 0.65, so the initial inspection frequency is determined to be 1/4. In the second case, it is assumed that the product is qualified for skip inspection in the first 10 batches - but 2 defective products are found in the sample of batch 1 with a sample size of 125, and the requirements of Table 2 are not met, so the initial skip inspection frequency is determined to be 1/3. In the third case, it is assumed that batches 3 and 11 are rejected and the product is qualified for skip inspection in batch 21. The number of batches required for qualification assessment has exceeded 20, so the initial skip inspection frequency is determined to be 1/2. 5.3 Reduction of skip inspection frequency
The permissible skip inspection frequency is 1/2, 1/3, 1/4 and 1/5, of which 1/5 cannot be used as the initial skip inspection frequency. If in state 2, the data of one or more consecutive inspection batches received meet the requirements of Table 1, and the sampling results of each inspection batch meet the requirements of Table 2, then the frequency used at that time can be changed to the next lower rate (for example, from 1/3 to 1/4), and the responsible department must approve the change of skip inspection frequency. Continue with the examples in 4.3 and 5.2. Assume that the first situation mentioned above occurs, and the initial skip inspection frequency is 1/4. Assume that the following 10 consecutive inspection batches are received (after skip inspection), with a cumulative sample size of 1,625 units and a total of 5 unqualified. In Table 1 with an AQL of 0.65, the minimum cumulative sample size for 5 unqualified is 1,508 units, so the requirements of Table 1 are met, and the sampling results of each batch meet Table 2. At this time, the skip inspection frequency can be changed from 1/4 to 1/5. 5.4 Inspection batch selection procedure (State 2)
The inspection batches in state 2 should be randomly selected according to GB10111 "using random number distribution for random sampling method" so that each product batch is determined with the corresponding skip inspection frequency as the probability to determine whether it should be inspected. However, at least one batch should be inspected in a certain cycle agreed upon by the supplier and the responsible department. If no cycle is specified, two months should be taken as a cycle. The average batch record of product batches submitted in state 2 (including state 3) should be the same as the average batch record during the qualification assessment period, and the general inspection level defined by GB2828 is 1, 1, 1 The regular inspection under 11 should be effective. In state 2, it is important that the supplier does not know which batches will be inspected before the product batches are handed over to the inspection agency.
5.5 Batch skipping interruption procedure
GB/T13263-91
When one batch does not meet the requirements of Table 2 or a second sample is required for secondary sampling, the batch skipping inspection should be interrupted and enter state 3. 5.6 Requalification procedure
If the batch skipping inspection is interrupted due to the reasons in Article 5.5, as long as 4 consecutive batches (excluding resubmitted batches) are received in state 3 and the last 2 batches meet the requirements of Table 2, the batch skipping inspection can be resumed. If the batch skipping inspection is interrupted before If the skip inspection frequency is not 1/2, then this frequency should be increased to the next higher level (for example, from 1/4 to 1/3), otherwise, a skip inspection rate of 1/2 should be used. Continue with the examples in 4.3, 5.2 and 5.3. The slower is that the skip inspection frequency is 1/5, and 1 batch is rejected during the skip inspection. Because the rejected batch must not meet Table 2, the batch inspection is interrupted. Now assume that 4 inspection batches are received starting in state 3, and 1 defective product is inspected in each of the last 2 batches with sample sizes of 125, which meets the requirements of Table 2. Therefore, the product can resume skip inspection at a skip inspection frequency of 1/4. 5.7 Disqualification
If one of the following situations occurs, the product will be disqualified Skip batch inspection qualification, return to state 1a. One batch is rejected in state 3:
b. Qualification re-evaluation failed within 10 batches +C. No production activities within the basic cycle agreed upon by the supplier and the responsible department (if no cycle is specified, two months should be regarded as a cycle)
d. The supplier significantly deviates from the written approved quality control procedures and violates the relevant requirements of Articles 4.1 and 4.2; e. The responsible department requires the return of the batch for inspection (for example, receiving a complaint from the purchaser, confirming that the quality is seriously affected, and the program conversion between state 2 and state 3 is frequent in a short period of time). The reason for the joint elimination qualification should be confirmed through documents. Continued 4. 3, 5.2, 5.3 and 5.6. Assuming that the first 3 batches are accepted in state 3, but the 4th batch is rejected, the procedure goes to state 1.
6 Supplier's responsibilities
The supplier shall notify the inspection body of any changes in the production or inspection methods, or any changes in the tools, quantities or materials used to produce the products.
The supplier shall provide the inspection body with a list including the technical specification number, drawing number, contract or order instruction number, shipping location, quantity and purchaser. For those product batches that pass without inspection by the inspection body, the supplier shall record the shipping date and give it to the inspection body together with the shipping mark, indicating that the product was shipped without inspection by the inspection body under the skip batch procedure. 7 Responsibilities of the inspection body and responsible department
The inspection body shall consider various factors such as production, inspection and product failure to determine whether the use of skip batch inspection is more effective than the use of relaxed inspection defined in GB2828. For this aspect, see Appendix A. When it is determined that skip-batch inspection is more cost-effective and the requirements of 4.1 and 4.2 are met, the inspection body shall submit a written report to the responsible department to establish the use of skip-batch inspection for the product. The written report shall include the following information:
Quality history.
b. Production cycle.
A copy of the supplier's current quality control procedures and a brief description of the supplier's ability to implement this procedure. Particular attention should be paid to providing an evaluation of the supplier's inspection methods, ability to test and control various characteristics, d. The date required to perform skip-batch inspection.
e. The required initial skip-batch inspection rate.
The responsible department shall consider the end use and safety status of the product and make a decision on whether the product can be skip-batch inspected. The responsible department shall review the information provided to determine whether the supplier has adequate management of all aspects of product quality. The responsible department shall determine the starting date for skip-batch inspection.
GB/T 13263-.91
The inspection agency shall inspect the supplier's quality assurance system within a certain period agreed upon by the supplier and the responsible department. If there is no clear period, the inspection shall be conducted every six months. Inspections between processes shall be regularly guided by the inspection agency. Table 1: Minimum cumulative sample size for initial skip batch inspection Number of nonconforming items
or nonconforming products
9 B00
11 090
14 850
47602860
17 29011 534
24 430
26 750
16 290
11 176
1 970 1 1 318
3 2142 089
14 117
190124
217 161
266173
2851185
340221
,1When the number of unqualified or non-conforming products exceeds, for each additional adjustment factor, the minimum cumulative sample size with 0 unqualified or non-conforming products is added once. For example, when AQL is 1,0, 22 unqualified or non-conforming products are recorded, and the minimum cumulative sample size is calculated as follows: (2×117)—2 7933027bzxz.net
GB/T13263-91
Table 2 The judgment number of initial or continued skip batch inspection (single batch inspection)
Sample
GB/T 1326391
武盘纪
Figure:
GB/T 1326391
Condition 1: Qualification of the supplier, procedure 4.1ab, c+Qualification of the product, procedure 4.2a, bc, d, e, f, name 10 batches or more are received in succession, the cumulative results meet Table 1, and the latest 2 batches meet Table 2, and the responsible department's approval. Condition 2: 10 batches or more are received in succession, the cumulative results meet Table 1, and each batch meets Table 2; the responsible department's approval. Condition 3\: There is no production activity in the specified period. The supplier violates 4.1 or 4.2 requirements; the responsible department requires to return to the inspection batch by batch.
, 1) One of these events occurs and returns to status 1: Start
10 batches are received in batches 11, meeting the requirements of Table 1
The frequency is 1/2
That is, batch inspection qualification is sufficient
20 batches are qualified
The rate is 1/3
Inspect batch by batch
The following batches
This batch
All meet Table 2
The frequency is 1/day
Figure 2 Determination of initial skip inspection frequency
GB/T13263-91
Appendix A
Factors to be considered when choosing skip inspection or relaxing inspection (supplement)
When choosing to skip batch inspection or relax inspection, three main factors should be considered: ugly. The relationship between the supplier and the buyer.
b The relationship between the fixed cost of inspection and the cost of inspecting a single product. C: The number of qualified decisions of the sampling plan used in batch inspection. The first factor includes a full understanding of skip batch inspection. When choosing skip batch inspection, mutual trust between the two parties is necessary, which is very important because some product batches will be shipped without inspection. If the supplier behaves irresponsibly, it may be very costly for both parties.
The second factor is economic considerations. Fixed costs may include the installation and use fees of test equipment, travel expenses of inspectors, storage and custody fees of product batches, and insurance premiums. If these fixed costs exceed the savings obtained from relaxed inspection, then skip batch inspection should be used.
The third factor is the number of qualified decisions in batch inspection. Since it has been stipulated in Chapter 1 that sampling plans with a qualified decision number of 0 are not used in states 2 and 3 (this is because the statistical characteristics of skip batch inspection are very poor at this time), then when the qualified decision number is 0, relaxed inspection should be used.
Additional Notes:
This standard was jointly drafted by the Electronic Standardization Institute of the Ministry of Machinery and Electronics Industry, the Institute of Systems Science of the Chinese Academy of Sciences, and China Textile University.
The main drafters of this standard are Wang Yan, Feng Yong, Wang Shujie, and Fan Jidong.
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