What Does AQL 2.5 Mean in Quality Inspection? | AQL Standard

If you conduct product inspections, you must have come across the term AQL and AQL 2.5.

Acceptance Quality Limit is typically abbreviated by AQL. It is the worst tolerable quality level. It represents the maximum number of defective units in a shipment that can be accepted. If the number exceeds the tolerable limit, the whole shipment will be rejected. Importers commonly set different AQLs given the type of products and level of faultiness such as critical, major, and minor defects.

Why Is Acceptance Quality Limit Important?

It is an important tool in performing sampling inspection. The inspection team can use the AQL standard to decide the follow-

  •  The number of units to be inspected in a given sample, and
  •  The number of defective units that will cause a “fail” result.

The AQL Chart: How it Works

The AQL chart determines how many units you should inspect and how many defects you can accept during the pre-shipment inspection.

How to use AQL Table? Please check here to determine the sample size

What does AQL 2.5 mean?

AQL 2.5 is a common criterion while we talk about shipment inspection and status of the shipment inspection.

AQL 2.5” is a special application of the ISO 2859-1 standard. AQL 2.5 is a quality tool during pre-shipment inspection to measure the quality of items. Other normative bodies like ANSI (American National Standards Institute) have also defined AQL 2.5 almost similar way.

ISO2589-1:1999 Sampling Procedures For Inspection By Attributes — Part 1: Sampling Schemes Indexed By Acceptance Quality Limit (AQL) For Lot-By-Lot Inspection

Since acceptance quality limit (AQL) symbolizes the acceptable mean of defective items of the entire sample in either percentage or ratio. Consequently, AQL 2.5 actually mean 2.5% defective rate of a particular shipment or sample is acceptable.

Defects classification and Acceptance Quality Limit (AQL)

All kinds of defects are broadly classified into three major categories such as critical, major and minor defect.

Fitting AQL 2.5, you are going to accept goods at a rate of 2.5% defects regardless of the type of fault. It is obvious that the degree of the repercussion of any defectiveness varies from product to product. 0.5% critical defects may bring about a significant loss than that of 2.5% minor defects.

There are some defects which lead product to deteriorate its functionality to a great extent, whereas some other defects can be ignorable and do not affect its performance. That’s why every buyer should classify its defects based on its level of impact on overall product performance. Upon identifying this, the buyer should fix the AQL according to the type of defect.

Following figures are commonly seen in the quality control industry-

  •  AQL 0 for critical defects,
  •  AQL 2.5 for major defects
  •  AQL 4.0 for minor defects

Check more about the 3 Defect Classification in Product Inspection and Examples of Quality Defects in Different Products

How does AQL 2.5 Standard Help Ensure Good Quality Inspections?

AQL 2.5 is an important tool for buyer or inspection services provider to determine how to conduct inspections. It determines the required sample size to be inspected and the number of rejected units to be accepted during quality inspection.

Though you can use general Inspection Levels in most cases, inspecting a large number of units is not feasible quite often. As a result, you have to incorporate a suitable inspection method like AQL 2.5

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Author: AQI Service as a professional quality control service company in China specialized in providing a complete range of quality inspection and testing certification services in China & Asia for global importers, buyers, retailers, and sellers.

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