What is Accepted Quality Level (AQL)? Types of AQL Defects and Levels of Quality

Accepted Quality Level (AQL) is a quality control process where a minimum threshold is set which has to be achieved by a batch of manufactured products. If there are more defects than AQL, the batch is completely rejected. AQL sets the standards of manufacturing and quality of a product and it helps companies avoid too many defects in the production of a good.

The quality of goods is usually checked via sampling. A set of standards is set for the batch of products and it may vary from industry to industry. If the batch of products meets the benchmark, they are said to have the AQL while if they fail to achieve the said standard, the entire batch of products is rejected. The quantity in the percentage of rejection is known as rejected quality level.

For example, suppose a certain product has a quality level of 2.5%. It means that 25 products in a batch of 1,000 are acceptable. If 26 products are found to have defects, the entire batch is rejected.

AQL depends on various financial, operational, and business norms. It is also related to risks as human use of products that are risky can lead to the potential harm of the customers. For example, healthcare industry products need to have a low AQL than other products as higher AQL would mean more risks to the health and wellbeing of individuals.

Customers however want a zero-defect product irrespective of the good's use which is sometimes hard to meet by the manufacturer. So, a mutual standard of AQL is set so that both parties can remain in a safe and relieved situation.

Types of AQL Defects

Following are the types of defects in AQL −

  • Critical Defects − These have a zero-defect policy as the goods are meant to be used in risky situations. Healthcare products fall in this category.

  • Major defects − These defects fall in the category where the AQL is set at 2.5%.

  • Minor defects − This category deals with less risky or less harmful products and the rate of AQL in such categories is 4%.

Levels of Quality

Following are the Levels of Quality

  • Accepted Quality Level (AQL) − As mentioned, AQL is the worst possible quality level. The decision of AQL is taken based on requirements and the use of products.

  • Rejected quality level (RQL) − RQL is an unsatisfactory level of quality that leads to the rejection of the products' batches.

  • Indifferent quality level (IQL) − This falls in between AQL and RQL. The amount of quality in this category is determined mutually by buyers and sellers.

Points to Note

  • AQL is the lowest value of defects that is tolerable.

  • If the goods fall in the Rejected Quality level category, the entire batch of sample products is rejected.

  • AQL is relevant to the Six Sigma quality control policy.