Understanding Acceptable Quality Level (AQL) as per ISO 2859

What is AQL ?

The Acceptable Quality Level (AQL) is a crucial metric in quality control that helps determine the maximum number of defective items that can be accepted in a production batch during random sampling inspections. According to the ISO 2859-1 standard, AQL is defined as the “worst tolerable” quality level. It is usually expressed as a percentage or ratio, indicating the number of defects relative to the total quantity produced. For example, if a batch of 5,000 units has an AQL of 1%, this means that up to 50 defective items (1% of 5,000) can be considered acceptable for that batch.

Importance of AQL

AQL plays a vital role in helping manufacturers and buyers agree on acceptable defect levels for products. It ensures that quality standards are met while balancing the risk of accepting defective products against the cost and effort of inspection. Different industries may have varying AQL standards, with more stringent levels applied to products where defects could pose significant risks, such as in the medical or aerospace industries.

How is AQL Determined?

The AQL methodology is based on the ISO 2859-1 standard, which provides a systematic approach to sampling inspections. This standard ensures precise and reliable quality assessments by defining the acceptable quality levels for different types of defects, such as critical, major, and minor defects.

Critical Defects: These are defects that could cause harm to the user or make the product unsafe. For example, in the electronics manufacturing industry, a critical defect might be a short circuit on a printed circuit board (PCB), which could pose a fire hazard.

Major Defects: These are defects that may affect the product’s performance or reduce its usability, but do not pose a safety risk. For instance, a major defect in an electronic component could be an incorrect resistor value that affects the functionality of a device. .

Minor Defects: These are defects that do not significantly impact the product’s performance or usability and are often related to aesthetics. An example of a minor defect could be a cosmetic scratch on the casing of a consumer electronic device, like a smartphone.

Using the AQL Calculator

To simplify the process of determining the appropriate sample size and acceptance number for your inspections, we have designed an XLS based Calculator . This tool helps you calculate the necessary parameters based on your specific requirements, ensuring that your quality control process is efficient and effective. Users can download this tool and share with others for using in the Industry.