AQL Inspection Levels for Sports Bra Shipments
Telling a factory to inspect at AQL 2.5 and nothing else is the most common mistake in activewear sourcing. AQL is a statistical tool with defaults that were never written for a garment whose function depends on dimensional accuracy. A bra can pass a standard inspection while carrying a systematic error in underband length that makes an entire size run unwearable. The buyer job is to define the defect list, the measurement points and the switching rules, not just the accept number.
What AQL Measures and What It Does Not
AQL sampling under ISO 2859-1 or ANSI/ASQ Z1.4 is attribute sampling by count of defective units. It gives a statistically defensible accept or reject decision for a lot at a stated quality level. It does not guarantee zero defects: at AQL 2.5 with a 200-piece sample, ten defective pieces are accepted. It also does not detect a systematic fault that affects every unit in the same way, which is exactly what a wrong underband length or a mis-set cutting marker produces. That is why measurement checks on a small fixed sample must run alongside the AQL count.
Choosing Levels for a Support-Critical Garment
Set three levels, not one. Critical defects at 0 tolerance: broken needle fragments, sharp hardware edges, missing needle-detection clearance, and any contamination. Major defects at AQL 2.5 for a standard programme and AQL 1.5 for premium or first orders with a new factory: support failure, band twist, strap length mismatch beyond 5 mm, hook rows misaligned, skip stitches, open seams at the racerback junction, and underband circumference outside tolerance. Minor defects at AQL 4.0: thread tails over 3 mm, slight print misregistration, shade variation within a 4 gray scale rating between panels.
Reading the Sample Size Table Correctly
Use general inspection level II unless there is a reason to do otherwise. For a lot of 3,201 to 10,000 pieces the code letter is L and the sample is 200 pieces; at AQL 2.5 that gives accept 10, reject 11, and at AQL 4.0 accept 14, reject 15. For 1,201 to 3,200 pieces the code is K with 125 pieces, giving accept 7 reject 8 at AQL 2.5. For 10,001 to 35,000 the code is M with 315 pieces, accept 14 reject 15 at AQL 2.5. Cartons must be selected at random across the whole lot, not from the first pallets, and the inspector should record which carton numbers were opened.
Classifying Bra Defects Before the Inspection
Write the defect list and circulate it with the purchase order, because the inspector cannot classify what the buyer has not defined. Support-critical items belong in major or critical: hook tape with fewer than three rows or two columns, hook-and-eye that does not close on all rows, pad pocket opening that lets the pad rotate, cut-out edges that curl or are asymmetric left to right by more than 3 mm, elastic that has lost surface recovery, and any seam that opens when the band is stretched to 130 percent. Train the inspector with photos from the approved pre-production sample.
Add Measurement and Safety Checks Outside the AQL Count
Measure three to five pieces per size, not per lot, for underband relaxed circumference, strap length, cup depth and cut-out geometry, against the approved sample tolerances. These are pass or fail, not statistical. Separately require needle detection or metal detection records for the full lot, because an AQL sample of 200 pieces will never find a broken needle fragment in a 5,000-piece order.
Use Switching Rules Across Repeat Programmes
ISO 2859-1 defines normal, tightened and reduced inspection. Move from normal to tightened after two of five consecutive lots are rejected, stay there until five consecutive lots are accepted, and only then consider reduced inspection with the supplier data to back it. Skipping straight to reduced inspection on a repeat programme is how a stable supplier quietly drifts.
A well-specified inspection costs a few hundred dollars per shipment and is the last line of defence before a container leaves. It works only when the buyer has done the thinking about what counts as a defect.
