AQL Explained: Setting Acceptable Quality Limits

Why 100% Inspection is Rare

Checking every single unit is expensive and time-consuming. “Sampling” allows you to check a representative portion (e.g., 200 units out of 5,000) to get a statistical probability of the total quality. AQL sets the rules for this sampling.

Reading the AQL Table

The table has two parts:

1. Sample Size Code Letter: Based on your total order quantity (Lot Size) and Inspection Level (usually Level II).

Example: Order of 5,000 units -> Code “L”.

2. Acceptance/Rejection Numbers: Based on the Code “L” and your chosen AQL limit (usually 2.5 for Major defects).

Result: Inspect 200 items. Accept if 10 defects found. Reject if 11 found.

Defining Defects: Critical vs. Major vs. Minor

You must classify defects before inspection.

• Critical (AQL 0): Dangerous or illegal. (e.g., Sharp edge on a toy, mold, needle inside).

Tolerance: 0 allowed. One finding rejects the whole lot.

• Major (AQL 2.5): Functional failure. The customer would return it. (e.g., zipper stuck, electronics dead on arrival).
• Minor (AQL 4.0): Cosmetic issue. The customer might notice but won’t return it. (e.g., tiny scratch, untrimmed thread).

Setting Your Standards (Manufacturer vs. Retailer)

• Standard Consumer Goods: Critical 0 / Major 2.5 / Minor 4.0. (This is the industry default).
• Luxury Goods: Critical 0 / Major 1.0 / Minor 2.5. (Tighter tolerance).
• Industrial Parts: Often custom tolerances based on dimensions, not AQL.

Checklist: Preparing for Inspection

• Defect List: Provide the inspector with a list of “Known Issues” to look for.
• Golden Sample: Does the factory have a signed “Perfect Sample” to compare against?
• Equipment: Does the inspector need special tools (calipers, light box, barcode scanner)?
• Draft Clause: Does your contract state “If inspection fails AQL, factory pays for re-inspection”? [[INTERNAL:drafting-manufacturing-agreements]]

FAQ

Q1: If the lot is rejected, do they throw it all away?

A: No. The factory must “Rework” (fix) the goods. Then you perform a “Re-inspection” (at their expense) to ensure the bad ones are gone.

Q2: Can I choose AQL 1.0 for everything?

A: You can, but the factory will charge you a higher unit price to account for the higher scrap rate and slower production.

Q3: Does the inspector check inside the box?

A: Yes. AQL inspection includes packaging checks (barcode scan, drop test, carton weight).

Key Takeaways

• Be Specific: Don’t say “No Scratches.” Say “Scratch visible at arm’s length = Major Defect.”
• Enforce Consequences: A failed inspection must have a financial penalty (re-work + re-inspection fees).
• Level II: This is the standard inspection level. Use Level I only if budget is tight and risk is low.
• Critical is 0: Never accept unsafe products.