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How to run a quality inspection using the AQL procedure

Acceptable Quality Limit (AQL) is a standardized quality control procedure used by brands, manufacturers and 3PLs, to ensure products meet the agreed upon quality standards.

Introduction


The Acceptable Quality Limit (AQL) procedure is defined in depth by the International Organization for Standardization in ISO 2859-1. This guide provides a quick reference to help you run the AQL process yourself.

The theory behind AQL is that by randomly selecting a statistically significant subset of units within a larger lot, you can quickly determine the quality of the entire lot.

The number of units sampled in the AQL process is dependent on which inspection level is used and the total number of units in the lot. For this guide we use AQL 2.5 Inspection Level S4, as it is the standard level prescribed by Lumi for all parties.

Step 1 – Determine your sampling plan


Start by determining how many units will be in your sample batch. The number of sample units depends on the total number of units in the lot. The lot is typically all of the units in a production run.

Once you've determined how many units will be in your sample batch, take note of the maximum number of units with minor, major and critical defects that are acceptable for the lot.

Total units in lot Units in sample batch Maximum units with minor defects Maximum units with major defects Maximum units with critical defects
1,201-3,200 32 2 2 0
3,201 - 10,000 32 2 2 0
10,001 - 35,000 50 3 3 0
35,001 - 150,000 80 5 5 0
150,001 - 500,000 80 5 5 0
500,001 - 1,000,000 125 7 7 0

Step 2 – Randomly select the sample units


To get a representative sample, randomize your selection of units throughout the lot. The units should be picked randomly across the top, middle and bottom of the pallets and bundles you have received. 

Tip: You can use a random number generator to help you randomize which pallets or bundles to pick from. Avoid picking only from the top of the pallets so that you get a true representation of the entire lot.

Step 3 – Inspect each unit in the sample batch


Find the inspection criteria for your product. You can browse quality standards by product, or find them by browsing the Lumi Catalog.

The inspection criteria provides a standardized list of defects to look out for, and what tolerances are permitted.

Examine each of the items in your sample batch. When you see imperfections, make a note of their severity (minor, major, or critical), and the number of units that are affected. 

Take photos of the defective units so that they can be reviewed by the Lumi team and manufacturers for root cause analysis.

Is your product missing quality standards? We consistently review and update our standardize quality criteria. If you ordered a product and the tolerances are not listed, contact your Lumi account manager.

Step 4 – Determine the number of defective units


If the number of units with minor, major or critical defects is below the maximum acceptable for your lot, it passes inspection. Hooray! You're done.

If the number of units with defects exceeds the maximum acceptable for your lot, please report issues within 48 hours. To speed up the process, help us estimate the total number of defective units. Typically defective units within a production run will be found in close proximity to each other. 

Per our terms of service, quality issues must be reported within 48 hours of a shipment’s delivery to be eligible for remake or refund. If your report is not submitted with 48 hours of delivery, it will be assumed that the lot was accepted. If you discover an issue after this period of time, you can still submit a quality report, so that the issue can be prevented in the future.

Step 5 – Report any quality issues


Each reported quality issue directly affects the scoring of our manufacturing partners and keeps our factory network top notch. Here's how to report a quality issue: 

  1. Log in to your Lumi account.
  2. From the Production view, click on the order item that has a quality issue.
  3. At the top right of the order item page, click the blue button to "Report a quality issue".
  4. Fill out the issue report.

Next steps for issue resolution


Manufacturers will typically produce up to 10% more units than the ordered quantity — aka "overs". Overs add some buffer room to account for potential quality issues in your order. Overs are billed after your order has been delivered, which allows us to compensate for any defective units that need to be subtracted from your invoice.

If the number of defective units dips below your order quantity by more than 15%, Lumi will take action in the following way:

  • For critical defects: Lumi will initiate a remake of the items affected to meet the ordered quantity.
  • For minor or major defects: Lumi will review the order, provide a root cause analysis, and a case-by-case correction action plan.

Lumi takes a proactive approach to continuously measuring and improving the quality standards of manufacturing partners in our network. If severe quality issues are found, or a factory exhibits consistently poor quality, this will be reflected in the manufacturer's scorecard and rankings on the platform. If this unusual situation occurs, Lumi will assist you in moving production to a different factory.