What is Acceptance Quality Level (AQL)

AQL 2.5 refers to the acceptable level of major defective goods, which is limited to 2.5% of the total order quantity. If the defect level in the batch produced exceeds 2.5%, it indicates that the product quality does not meet the agreed standards.

Level 2 AQL is generally considered the standard, except for cases where the sample size is small. However, Level 1 AQL only requires 40 percent of the inspection level of Level 2 and is suitable for situations where less differentiation is necessary. On the other hand, Level 3 AQL requires 160 percent of the inspection level of Level 2 and is useful for minimizing the risk of accepting a lot with an excessive number of defects.

The ANSI/ASQ Z.14 standard recommends conducting a 100 percent inspection when the AQL sample size is equal to or greater than the lot size. Additionally, it is the responsibility of the supplier to perform a 100 percent inspection before an independent inspector conducts a secondary check on the goods.

The AQL 4% refers to minor defects in a product. These defects may not significantly affect the product’s intended purpose, but they do not meet the specified standards. Despite these defects, some end-users may still purchase the product.

AQL .65 refers to the minimum acceptable level of quality for a specific population or pre-determined sample size. To illustrate, if someone says “AQL is 0.65%,” it implies that they expect the overall defective items in the entire order quantity to be no more than 0.65%, on average, across multiple production runs with that supplier.

To choose your AQL level, it is important to take into account your product and market. For instance, if you are dealing with high-end products, lower AQL levels might be more suitable. Conversely, if you are dealing with lower-end products, higher AQL levels might be more appropriate. Additionally, it is advisable to adjust your inspection levels based on your relationship with the factory.

The quality of a glove product batch is measured by AQL, which sets the maximum number of defects allowed in a random selection. Therefore, a lower AQL indicates higher quality and reduces the probability of defects.

During a regular inspection, the AQL level typically falls between 0.065 and 6.5. The higher the AQL level, the more relaxed the inspection standards. For inspecting consumer products, the AQL level is usually established at 2.5, indicating no tolerance for critical defects, 2.5 for major defects, and 4 for minor defects.

The rejection criteria for a sample size of 315 units with an AQL of 2.5% for major defects and 4% for minor defects are as follows: if there are 15 or more major defects and 22 or more minor defects, the lot will be rejected. This information can be found in Table 1 under the letter M.

The Acceptance Number (c) refers to the maximum number of non-conformances that are allowed within the sample. The Sample Size (n) is the number of samples that need to be inspected. Additionally, single sampling plans have a rejection number (r) that is always one non-conformance more than the acceptance number (c).

Suppose you receive a shipment of 10,000 coffee mugs and decide to use acceptance sampling. You randomly select 28 mugs for inspection, and if the number of defective mugs is 0, 1, or 2, you can accept the entire shipment. However, if the sample contains more than 2 defective mugs, you must reject the entire lot.

AQL sampling involves selecting one or more samples randomly from the shipment and comparing them to a “golden” sample that is considered to be perfect. Generally, AQL sampling adheres to the ISO 2859-1 (or ANSI/ASQ Z1.4) standard for sampling.

AQL, which stands for Acceptable Quality Level, is a statistical sampling technique utilized in quality control to assess whether a batch of products satisfies a specific quality standard. Its primary objective is to guarantee that products meet the anticipated quality level and to avoid the delivery of faulty products.