Introduction to AQL chart and
its application in Textile
Inspection
by
Name: Ayan Mukherjee
Dept. : Textile Technology
Roll: 11001422006
Reg. no: 221100110144
Sem: 5th
PC TT 504
Textile Testing II
(Presented for the fulfilment of CA1 Exam)
Govt. College of Engineering & Textile Technology, Serampore, 712201
What is AQL chart ?
Introduction:
Acceptable Quality Limit table refers to the ANSI ASQ Z1.4 table used by QC inspections
professionals for AQL sampling during the inspection. This AQL sampling plan is designed to
help in determining the right sample size for inspection and the acceptable number of
defects. Insight into the dynamics of the AQL table can also enhance your understanding
and the interpretation of inspection results. It is vital for data-driven decision-making.
➢ It is a statistical method to determine the number of defects allowed in a shipment,
yet still acceptable from an overall quality standpoint.
Need for Random Sampling
Whether you own a retail shop, online business, or work as a Quality Control professional,
you will need to evaluate the quality of goods or materials before they are shipped. A 100%
check of products may be possible during or at the end of production if your product is high
value, high risk, or your order is a small quantity. Otherwise, a 100% inspection of the goods
or material is not viable due to restrictions on time and manpower. It may not even be
practical if the inspection includes a destructive test.
AQL application method
The ANSI ASQ Z1.4 AQL consists of 2 tables.
The first table lists all the different sample
size codes (A, B, D...) based on 2 inputs: The
“inspection levels” and the “lot or batch size”.
There are 7 levels, and from the left to the
right, the number of samples to be pulled out
for inspection keeps increasing. There are 3
general inspection levels (G1 to G3) and 4
Special inspection levels (S1 to S4).
Using this table, one can determine the
sample size code which will be used next
step in AQL table 2.
AQL application method (contd..)
The second table lists various sample
sizes (top to bottom - 2 to 2000) and
the acceptance and rejection
numbers against the various AQLs (left
to right - 0.065 to 6.5).
Using this table, one can determine
the maximum number of defective
products one can accept (Ac) in the
lot and the no. of defective products
(Re) that will fail the inspection if
present.
Application of AQL in textile inspection
Despite giving us the idea about sample size and the no. of allowable defects in the sample, AQL can also
be used to detect the severity of the defect.
Critical Defect Major Defects Minor Defects
Critical defects are the most serious defect Less serious than critical defects, major Most importers use AQL standard of 4.0 for
category under the AQL table. Importers defects are usually accepted in limited minor defects, this is the least serious
typically use a 0 tolerance policy for critical quantities. Typically, importers will assign defect category, however, it can still cause
defects (AQL of 0.0) the AQL standard limit. (normally AQL 2.5) the rejection of your order if found in large
quantity.
Example of critical defects: Example of major defects: Example of minor defects:
❖ Mold ❖ Holes or tears on a fabric ❖ Untrimmed threads on a garment or
❖ Broken needle in a garment ❖ Out of tolerance dimensions for plush toy
❖ Rusty items industrial components ❖ Minor color shading
❖ Exposed nails or sharp edges ❖ Missing buttons in clothes ❖ Removable small dust
❖ Hidden dent mark
References
o AQL Calculator | Acceptable Quality Limit | AQL Table | AQL Chart
(tetrainspection.com)
o AQL Acceptable Quality Limit (Step-By-Step Tutorial) | InSpec by BV
(inspec-bv.com)
o Acceptable Quality Level (AQL), Quality control, Sampling plan,
Defect rate, Inspection standards, Statistical process control
(textilecoach.net)
