Quality control is an indispensable part of any manufacturing process to ensure that products meet the required standards before reaching the consumer. Manufacturers rely on various quality control methods, including the Acceptable Quality Limit (AQL) sampling, to achieve this goal. AQL sampling is a statistical method that enables manufacturers to determine whether a batch of products meets the required quality level. In this blog post, we will provide a comprehensive guide on the AQL sampling table, a vital tool in the quality control process.

Before we delve into AQL, let’s understand what is AQL. The Acceptable Quality Level (AQL) refers to the maximum allowable defect rate that is considered tolerable, as established in ISO 2859-1. The AQL provides the limit on the acceptable number of defective components in random sampling quality inspections. Typically, it is expressed as a ratio or percentage, representing the number of defects relative to the total quantity.

What is AQL Sampling Table?

An AQL sampling table is a chart that contains different sampling plans based on the AQL level, lot size, and sample size. It is a tool that helps you decide whether to accept or reject a batch of products based on the number of defects found during the inspection.

Any industry that produces goods or products that need to meet specific quality standards can benefit from the use of AQL sampling tables. By ensuring defects are caught early in manufacturing, companies can improve quality, reduce costs, and maintain a positive reputation with customers. The industries that use AQL tables include, but are not limited to:

• Automotive: The automotive industry is one of the sectors that rely heavily on AQL sampling tables. This is because the industry greatly prioritises quality and safety standards, and any defects can lead to disastrous consequences.
• Manufacturing: Manufacturing companies use AQL sampling tables to ensure their products meet quality standards. Manufacturers can identify defects and adjust their production processes to improve quality by inspecting random samples of finished goods.
• Textiles and apparel: In the textile and apparel industry, AQL sampling tables are commonly used for garments inspection such as holes, stains, or loose threads. This is particularly important in the fashion industry, where high-quality garments are essential to help maintain the brand's reputation and customer loyalty.
• Electronics: Electronics manufacturers rely heavily on AQL sampling tables to ensure their products meet safety standards and work as intended. This is especially important in the aerospace and medical devices industries, where even small defects can have serious consequences.
• Food and beverages: AQL sampling tables are used in the food and beverage quality control to ensure that products meet safety and quality standards. By inspecting random samples of food products, manufacturers can identify contaminants and ensure that the product is safe for consumption.
• Pharmaceuticals: In the pharmaceutical industry, AQL sampling tables ensure that medications are safe and effective. By testing random samples of finished products, manufacturers can identify any defects or inconsistencies in the manufacturing process and take corrective action swiftly.

AQL Methods

There are three types of AQL methods: single, double, and multiple.

Single Sampling Plan: When a lot size is small and the inspection is less critical, a single sampling plan is used. This method involves taking a single sample and inspecting it for defects. The lot is considered acceptable if the number of defects found in the sample is equal to or less than the Acceptable Quality Limit (AQL). However, the lot is rejected if the number of defects found exceeds the AQL.

Double Sampling Plan: The double sampling plan is often utilised when dealing with larger lot sizes or more critical inspections. This method involves taking two samples, with the first sample being inspected. The lot is accepted if the number of defects found in the first sample is less than or equal to the specified AQL. However, a second sample is taken if the number of defects exceeds the AQL. Following the second inspection, the lot is accepted if the total number of defects across both samples is less than or equal to the AQL. If not, the lot is rejected.

Multiple Sampling Plan: In situations where the inspection of a large lot is critical, multiple sampling plans are the preferred method. With this approach, three samples are taken, and if the number of defects found in the samples is within the AQL limits, the lot is deemed acceptable. However, if the number of defects exceeds the AQL, additional samples are taken, and the process is repeated until a conclusive decision can be made. This method ensures that the inspection process is comprehensive and that any defects are accurately identified and remedied. By utilising multiple samples, manufacturers can make informed decisions about the quality of their products and take the necessary corrective actions to maintain the highest level of quality control.

How to Read AQL Table?

The AQL table is typically presented as a quality control chart specifying the acceptable and non-acceptable levels of defects for a given sample size and level. The table provides information on the number of samples to be taken, the maximum number of defects allowed, and the corresponding AQL level. Here are the steps to read an AQL table:

• Identify the AQL level: Determine the maximum allowable percentage of acceptable defective products. Selecting an appropriate AQL level is crucial based on the product's importance and the risks associated with defects.
• Identify the lot size: The lot size refers to the number of products in the batch. Choosing a representative lot size for the entire production run is essential.
• Identify the sample size: The sample size is the number of products selected for inspection. This should be chosen based on the lot size and AQL level.
• Determine Accept or Reject Criteria: After identifying the AQL level, lot size, and sample size, determine the acceptable number of defects in the sample. The lot is accepted if the number of defects found in the sample is equal to or less than the acceptable number of defects. On the other hand, if the number of defects exceeds the acceptable number, the lot is rejected.

How to Determine Defects Using AQL Sampling Table?

To determine whether a batch of products meets the specified quality standard using the AQL sampling table, follow these steps:

1. Determine the sample size and AQL level based on the batch size and necessary confidence level.
2. Draw the specified number of samples from the batch based on the sample size determined in step 1.
3. Inspect each unit in the sample and record the number of defects.
4. Determine whether the number of defects in the sample is within the acceptable limit specified in the AQL table.
5. The batch is accepted if the defects are within the allowable limit. The batch is rejected if the number of defects exceeds the permissible limit.

Conclusion

Now that you kwno what is AQL and it’s importance, it is imperative to hire the right quality control solution experts to ensure quality assurance for your products. At Global Inspection Managing, we understand the importance of quality control in the business. That's why we offer comprehensive inspection and audit services to help enterprises ensure their products' quality. Our experienced and professional auditors are accredited in line with international standards. We use state-of-the-art technology and equipment to provide accurate and reliable results. Our services include AQL sampling, factory audits, and product inspections. Contact us today to learn more about our services and how we can help your business ensure the quality of your products.

AQL sampling table is an essential tool for ensuring the quality of products. By using this statistical sampling method, businesses can identify the acceptable and non-acceptable levels of defects in a batch of products and make informed decisions about whether to accept or reject the batch. Following the correct method and reading the table properly ensures accurate and reliable results.