The Acceptable Quality Level (AQL) is a widely used quality control standard that provides a balance between full inspection and no inspection. It defines the number of samples to be selected from a lot or consignment for inspection and sets the maximum allowable number of defective items within that sample.

The AQL standard is intended to give manufacturers and consumers confidence in the quality of a product without having to inspect every item. The goal is to ensure that the quality of the product meets specific standards while minimizing inspection costs and time.

How AQL Works:

  • If the lot passes the sampling plan, it can be confidently stated that, with 95% confidence, the quality of the lot is at or better than the AQL (i.e., defective rate < AQL).
  • If the lot fails the sampling plan, it can be confidently stated that, with 95% confidence, the quality of the lot is worse than the AQL.

Sampling Plan Used at Asiapack:

Asiapack follows the Single Sampling Plan Normal Level I standard, which is designed to ensure that no critical defects are accepted. For different defect levels, the following AQLs are applied:

  • Major defects: AQL 2.5
  • Minor defects: AQL 4.0

This is the standard commonly required for consumer products to maintain acceptable quality while ensuring that defects do not affect product usability or safety.

Defect Classifications:

Defects detected during visual inspections are classified into three categories:

  1. Critical Defects:
    • Likely to result in unsafe conditions or violate mandatory regulations.
    • These defects cannot be accepted under any circumstances.
  2. Major Defects:
    • Reduces the usability of the product or causes obvious appearance issues.
    • While these defects may not necessarily make the product unsafe, they are still significant enough to affect the overall product experience.
  3. Minor Defects:
    • These defects do not affect the usability of the product but do exceed the defined quality standards.
    • They are less impactful than major defects but still need to be addressed.

Customer-Specific Defect Classifications:

Customers have the option to specify what qualifies as minor, major, or critical defects within an inspection checklist, which can include inspection criteria and product specifications. This ensures that each customer’s unique requirements and product standards are met.

AQL Table for Sample Calculation:

The AQL table is used to determine the required sample size based on the total shipment quantity. It also indicates the maximum number of defects allowed within that sample size to ensure the shipment passes the inspection.

Acceptable Quality Levels - AQL Level I
Lot size Sample size
Max defects
Major
2.5
Max defects
Minor
4
2 - 90 5 0 0
91 - 150 8 0 1
151 - 280 13 0 1
281 - 500 20 1 2
501 - 1,200 32 2 3
1,201 - 3,200 50 3 5
3,201 - 10,000 80 5 7
10,001 - 35,000 125 7 10
35,001 - 150,000 200 10 14
150,001 - 500,000 315 14 21

 

Samples are randomly drawn from the square root of cartons (√(total number of cartons). i.e. If 100 cartons, you need to select samples from 10 different cartons, and randomly within those cartons. We use the AQL table to calculate the number of sample drawn depending on shipment Quantity.

Example 1
If the lot has 200 pieces, 13 samples should be randomly taken out,
If no more than 1 minor defect found and no Major defect found, LOT ACCEPTED

If more than 1 minor defect found or 1 or more Major defect found, LOT REJECTED

Example 2
If the lot has 5.000 pieces, 80 samples should be randomly taken out,
If no more than 7 minor defects found and no more than 5 Major defects found, LOT ACCEPTED

If more than 7 minor defects found or more than 5 Major defects found, LOT REJECTED