Overview of Sampling Plan and AQL Index
In the field of product quality control, sampling plans are a crucial tool. They assist enterprises in evaluating the quality status of products with reasonable cost and efficiency. The AQL (Acceptable Quality Limit) indicator is a key parameter in sampling plans, which defines the quality level at which a product lot is considered to have acceptable quality in sampling inspection.
Detailed analysis of AQL indicators
We have a series of specific AQL index values, namely 0.1, 0.15, 0.25, 0.4, 0.65, 1, 1.5, 2.5 and 4. These values represent different quality acceptance standards. The lower the value, the higher the requirements for product quality. For example, when the AQL is 0.1, the enterprise has the strictest control over product quality, and only a very small number of non - conforming products are allowed to exist; while when the AQL is 4, the tolerance for non - conforming products is relatively higher.
Sampling situations under different batch sizes
The sampling plan will determine the corresponding sample size according to different lot sizes.
1. When the batch size is from 2 to 8: For this relatively small batch size range, it is marked with * under multiple AQL indicators. Here, * means that the entire batch needs to be inspected 100%. This is because the batch size is small, and a comprehensive inspection can more accurately assess the product quality and avoid missing unqualified products.
2. When the batch size is from 9 to 15: Similarly, for some AQL indicators marked with *, a full inspection is required. When the AQL requirements are relatively lenient, the sample size will vary. For example, under certain AQLs, the sample sizes are 13, 8, 5, 3, etc. This indicates that as the AQL indicators change, enterprises can select an appropriate sample size for inspection according to the actual situation.
3. When the batch size is between 16 and 25: As the batch size increases, the sample size is adjusted accordingly. Under some AQL indicators, the sample sizes are 20, 13, 8, 5, and 3. Different sample sizes reflect the decisions made by enterprises to balance inspection costs and quality assurance under different quality requirements.
4. When the batch size is from 26 to 50: The sample size changes further, such as 32, 20, 13, 8, 5, etc. This change is based on the need to ensure a certain level of inspection accuracy while considering the inspection efficiency and cost after the batch size increases.
5. When the batch size is from 51 to 90: The sample sizes include 80, 50, 32, 20, 13, 8, 7, 6, etc. It can be seen that as the batch size increases, the overall sample size also increases, but the increase is not linear. This is to optimize the use of resources while meeting the requirements of quality inspection.
6. When the batch size is from 91 to 150: The sample sizes are 125, 80, 50, 32, 20, 13, 12, 11, 7. Within this batch - size range, enterprises can flexibly select the sample size according to different AQL indicators to achieve the purpose of quality control.
7. When the batch size is from 151 to 280: The sample sizes are, for example, 125, 80, 50, 32, 20, 20, 19, 13, 10. At this time, the determination of the sample size comprehensively considers the batch size, the AQL index and the economy of the inspection.
8. When the batch size is from 281 to 500: The sample sizes are 125, 80, 50, 48, 47, 29, 21, 16, 11. Different combinations of sample sizes meet the inspection requirements under different quality requirements.
9. When the batch size is between 501 and 1200: The sample sizes are 125, 80, 75, 73, 47, 34, 27, 19, and 15. As the batch size increases, the adjustment of the sample size becomes more refined to ensure the effectiveness of quality inspection.
10. When the batch size is from 1201 to 3200: The sample sizes are 125, 120, 116, 73, 53, 42, 35, 23, 18. Enterprises need to arrange the sample sizes more reasonably within this relatively large batch size range to achieve a balance between quality and cost.
11. When the batch size is from 3201 to 10000: The sample sizes are 192, 189, 116, 86, 68, 50, 38, 29, 22. At this time, the determination of the sample size needs to consider the characteristics of large-scale production. It is necessary to ensure quality monitoring without excessively increasing the inspection cost.
12. When the batch size is from 10,001 to 350,000: The sample sizes are 294, 189, 135, 108, 77, 60, 46, 35, 29. Under such a large batch size, the scientific nature and rationality of the sampling plan are particularly important.
13. When the batch size is from 335,001 to 150,000: The sample sizes are 294, 218, 170, 123, 96, 74, 54, 40, and 29. Enterprises need to accurately select the sample size according to the actual production situation and quality requirements.
14. When the batch size is from 150,001 to 500,000: The sample sizes are 345, 270, 200, 156, 119, 90, 64, 40, 29. For ultra - large - scale batches, the formulation of the sampling plan needs to comprehensively consider multiple factors to ensure the stability of product quality.
Features of Plan C = 0
The C = 0 plan mentioned here is a special sampling plan. Here, C represents the allowable number of non-conforming products. C = 0 means that in the sampling inspection, once a non-conforming product is found, the batch of products will be judged as non-conforming. Moreover, the C = 0 plan has no conversion rules for tightened or reduced inspection. This indicates that the plan is relatively strict and fixed. Enterprises need to always maintain a consistent inspection standard when using it and cannot convert to tightened or reduced inspection according to the inspection results. This plan is suitable for occasions where extremely high product quality is required and no non-conforming products are allowed.