Sequential sampling plans for inspection by variables for percent nonconforming (known STANDARD deviation)
Some standard content:
GB/T 163071996
This standard is equivalent to ISO8423 "Metric sequential sampling test procedure for nonconforming product rate (with known standard deviation)". The difference between this standard and ISO8423 "Metric sequential sampling test procedure for nonconforming product rate (with known standard deviation)" is that the arrangement of ISO8423 "Metric sequential sampling test procedure for nonconforming product rate (with known standard deviation)" has been changed. In the "Scope\ chapter, the situation that the cost is high but the time is short and only applicable to the inspection unit's products is added.
Appendix A, Appendix B and Appendix C of this standard are all standard appendices, and Appendix D of this standard is a suggestive appendix.
This standard is proposed and coordinated by the National Technical Committee for Standardization of Statistical Methods Application. This standard is drafted by the Sampling Inspection Sub-Technical Committee of the National Technical Committee for Standardization of Statistical Methods Application. The drafting units of this standard are: China Institute of Standardization and Information Classification and Coding, Metal Products Research Institute of the Ministry of Metallurgy, Institute of Systems Science of the Chinese Academy of Sciences, Beijing University of Technology,
The main drafters of this standard are: Yu Zhenfan, Liu Wen, Chu Anjing, Ma Yilin, Gu Yejun, Yu Shanqi, Liu Qiong, GB/T16307-1996
ISO Foreword
ISO () is a worldwide federation composed of national standardization groups (ISO member groups). The work of formulating international standards is usually carried out by ISO's technical committees. The committee is completed. If each member group is interested in the standard project established by a technical committee, it has the right to participate in the work of the committee. International organizations (official or unofficial) that maintain contact with ISO can also participate in the relevant work. In terms of technical standardization, ISO maintains a close cooperative relationship with the International Electrotechnical Commission (IEC). The draft international standards formally adopted by the technical committee are submitted to the member groups for voting. The international standard must obtain the consent of at least 75% of the member groups participating in the vote before it can be formally adopted. International Standard ISO8423 was developed by the Acceptance Sampling Inspection Technical Committee of the Application of Statistical Methods of ISO/TC69.
Appendix A, Appendix B and Appendix C of this standard are part of this international standard, and Appendix D is for reference only. 1 Scope
National Standard of the People's Republic of China
Metrological Truncation Sequential Sampling Inspection Procedure and Sampling Table (Applicable to Cases Where the Standard Deviation is Known)
Sequentlal Sampling plans for inspection by yariables for percent nonconforming (known standard deviation)
1.1 This standard specifies the truncated sequential sampling inspection plan and procedure for discrete individuals, GB/T163071996
eqv IS0 8423:1991 Www.bzxZ.net
The truncated sequential sampling plan (hereinafter referred to as the sequential plan) in this standard is applicable to the situation where the number of nonconforming products per hundred units of products is the quality indicator, and the quality characteristics of the inspected products follow the normal distribution and the standard deviation is known. The sampling plan in the standard is indexed by the production risk quality and the user risk quality.
The sequential plan and procedure in Appendix A are based on the acceptable quality level AQL, mainly to match the sampling plan system in GB 6378-86.
This standard provides a sequential evaluation procedure for the inspection results. It can make the probability of acceptance very low when the quality of the product batch provided by the manufacturer does not meet the specified requirements, prompting the manufacturer to provide products with higher quality batches, and at the same time protect the user by setting an upper limit on the probability of acceptance of batches with poor quality.
This standard promotes the method of saving the most sample size under the same inspection accuracy. It is suitable for the inspection of unit products in a short time, the inspection of isolated batches, and the situation of large monthly batches. It is particularly required that the inspection batch size is greater than or equal to 7 times the truncated sample size. Note
When the inspection batch size is less than 7 times the truncated sample size, that is, <7 holes, the sampling plan standard is still used, but at this time the manufacturer's risk and the risk of the H party are smaller than the value determined in the standard 1
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2If the truncated sample size exceeds the inspection batch size, the sequential application plan will use the batch size as the truncated sample size. 1.2 The sampling plan in this standard is designed based on the following conditions being met. ) When the inspection procedure is used for continuous batches, all products in the batch are produced by the same production hall using the same production process. If there are multiple production parties, this standard should be used for each production party separately. b) Only a single quality characteristic of the product is considered, and the value of this quality characteristic can be measured by a continuous scale. If several quality characteristics of the product are important, then this standard is used separately. ) The production is stable, that is, its quality characteristic value follows a normal distribution or approximately follows a normal distribution, and the standard deviation is known. ) The contract or standard stipulates the upper specification limit U, or the lower specification limit, or the two-sided specification limit L of the quality characteristic of the product. If the upper specification limit is specified, when the quality characteristic value measured for an individual is greater than or equal to L, the product is considered to be a non-conforming product; if the lower specification limit L is specified, when the quality characteristic value measured for an individual is greater than or equal to L, the product is considered to be a non-conforming product; if the two-sided specification limit L is specified, when the quality characteristic value measured for an individual is greater than or equal to L+, the product is considered to be a non-conforming product. For the two-sided specification limits, it is also necessary to consider the risk of the tolerance side separately or the risk of the two sides together. It is divided into two situations: separate effective side specification limits or comprehensive two-sided specification limits. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard was published, the versions shown were approved by the State Technical Supervision Bureau on April 26, 1996 and implemented on November 1, 1996
GB/T 16307—1996
as effective. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB2828-87 Sampling procedures and tables for batch inspection by attributes (applicable to inspection of continuous batches) GB 3358.1:93 Statistical terms Part 1 General statistical terms GB3358.293 Statistical terms Part 2 Statistical quality control terms GB 4882-85 Statistical processing and interpretation of data for end-of-life inspection GB6378--86 Sampling inspection procedures and tables for measurement of nonconforming product rate (applicable to inspection of continuous batches) GB8051-87 Sequential sampling inspection procedures and tables for attributes 3 Definitions and symbols
3.1 Definitions
For the formulation of this standard, in addition to the terms and definitions in GB/T3358.1~3358.2-93, the following terms and definitions are also applied.
3.1.1 Unit unit
The basic unit for dividing products for the purpose of sampling inspection. 3.1.2 Sample unit sample unit
The unit product extracted from the batch for inspection. 3.1.3 Variables guality characteristic Quality characteristics of the inspected product that can be measured with a continuous scale: 3.1.4 Variables inspection The process of comparing the observed values of the metric quality characteristics of a unit product with the technical requirements under specified conditions by measurement, test or other methods, and judging whether the unit product is qualified. 3.1.5 Variables sampling inspection The process of randomly selecting some unit products from a batch for metric inspection according to the specified metric sampling plan, and judging whether the batch is accepted based on the sample mean and (or) sample standard deviation. 3.1.6 Sequential sampling inspection Each time, select one or a group of products from the batch, and after inspection, make a decision to accept or reject the batch or inspect another or another group of products according to a certain rule.
3..7 Nonconformity
Non-conformity of a characteristic of a product or process that does not meet the specification. 3.1.8 Noncanforming item Unit product with one or more nonconforming characteristics. 3.1.9 Specification limit The limit value used to determine whether a certain metrological quality characteristic of the unit product will be nonconforming. 3.1.10 Upper specification limit The maximum value of the qualified metrological quality characteristic specified by upper specification limit. 3.1.11 Lower specification limit The minimum value of the qualified metrological quality characteristic specified by lower specification limit. 3.1.12 Single specification limit Single specification limit The specification limit (or acceptable quality level AQL) of the manufacturer's risk quality and the user's risk quality is specified only for the upper or lower specification limit. 3.1. 13 Double specification limit Double specification limit The specification limit of the manufacturer's risk quality and the user's risk quality (or acceptable quality level AQL) is specified for the upper or lower specification limit at the same time
GB/T 16307—1996
The double specification limit of the manufacturer's risk quality and the user's risk quality (or acceptable quality level AQL) is specified for the upper and lower specification limits respectively.
3.1.15 Combined double specification limit Combined double specification limit The double specification limit of the total manufacturer's risk quality and the user's risk quality (or acceptable quality level AQL) is specified for the upper and lower specification limits.
3.1.16 Limiting process standard deviation for combined double specification limits (LPSD) limitingprocess standard deviation for combined double specification limits The limit of the process standard deviation under the condition of specified combined double specification limits. 3.1.17 Maximum process standard deviation for separate double specification limits (MPSD) maximum process standard deviation for separate double specification limits The maximum process standard deviation under the condition of specified separate double specification limits. 3.1.18 Cumulative sample size (neum) cumulativesamplesize The sum of all sample sizes required from the start to the end of sampling inspection when sequential sampling is carried out. 3.1.19 Curtailmentsampleaize The sample size that is specified in advance and that sequential sampling must end when the th unit product is sampled. 3.1.20 Average sample size average sample size When a sampling plan is used to make an acceptance or rejection decision, the average number of samples to be inspected per batch, 3.1.21 The minimum estimate of the quality levelU, the unit product is called a defective product. If the lower specification limit L is specified, when the quality characteristic value of the unit productOr L, the unit product is called a defective product. For the two-sided specification limit, it is also necessary to consider the risk of each side separately or consider the risk of both sides together, which is divided into two cases: discrete two-sided specification limit and comprehensive two-sided specification limit. 6.4 Provision of producer risk quality P4
Producer risk quality should be determined by negotiation between the producer and the user based on the quality requirements in the technical standards and the maximum sample size allowed.
6.5 Provision of user risk quality PR
User risk quality should be determined by negotiation between the producer and the user based on the quality requirements in the technical standards, taking into account the protection of the user and the maximum sample size allowed. 6.6 Retrieve sequential sampling plan parameters
Read Rg and 6.6.1 Example of single-sided specification limit
The minimum withstand voltage of a certain insulator is specified to be 200kV, that is, its single-sided lower specification limit L=200kV. A batch of this insulator was submitted for inspection. The production of the product was stable. Although the withstand voltage characteristics of the products in the batch changed, this value obeyed the normal distribution. According to the records, the standard deviation within the batch was stable, = 1.2kV. It was decided to use a sequential sampling plan that met the following conditions: a) If the defective rate of the submitted batch is 0.5%, the probability of accepting the batch is 0.95b) If the defective rate of the submitted batch is 2.0%, the probability of accepting the batch is 0.10. By setting the production risk point A = 0.5%, a = 0.05 and the user risk point = 2%, t = 0.10, the above requirements can be achieved.
For the one-sided lower specification limit, it can be found from the row where force=0.5 and the column where a2 is located in Table 1 that the required sequential sampling plan has the following parameters: h=4.312, h=5.536, g2.315, #, =496.6.2 Example of two-sided specification limits
6.6.2.1 Example of comprehensive two-sided specification limits
The size specification of a certain mechanical part is 205mm±5mm. The production of this product is stable, and the size of the parts in the batch is somewhat variable. The size value follows a normal distribution. According to the records, the standard deviation within the batch is stable, 0-1.2mm. It is decided to use a comprehensive two-sided specification limit sequential sampling plan with user=0.5%, α-0.05, user-2%, 3~:0.10. From Table 1, it can be retrieved that the parameter of the sampling plan is h. =4.312, =5.536, g=2.315 and =49. 6.6.2.2 Example of discrete two-sided specification limits
GB/T 16307 1996
Normal distribution, according to previous records, the standard deviation α within the batch is stable, 12mV. It is decided to use a variable sequential sampling plan with an upper limit parameter of =0.5%, αU)=0,05, =2%, Q(>=0. 10, upper specification limit = 6000㎡V and a lower limit parameter of p=2.5%, αL)=0.05, can =10%, p(L)=0.10, lower specification limit L=5900mV. Because the quality level of each specification limit must be determined separately, the sequential sampling plan must be used. From Table 1, the parameters of the upper specification limit are -4.312.n1=5.536.g(U>=2.315,m>=49. Similarly, the parameters of the lower specification limit are h)=3.318, h-4. 260.gL)=1. 621,n.)=29.
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