AQL Sampling

Statistical Framework

Standard tables from international normalization bodies dictate the relation between lot size and sample size. Sourcing agreements specify different limits for critical, major, and minor defects in the cell shipment. A critical defect like a metal particle in the jellyroll results in zero tolerance and immediate lot rejection.

Major defects that affect performance are allowed at a low percentage, such as one percent. Minor cosmetic defects hold a higher threshold of four percent. This tiered structure ensures that the factory focuses its quality assurance resources on safety-critical parameters.

Engineers use operating characteristic curves to calculate the consumer risk of accepting a bad lot. The sample size must be adjusted if a supplier shows a history of poor quality.

Testing Execution

Incoming quality control teams extract the required number of samples randomly from different pallets. These units undergo electrical testing and dimensional verification to confirm compliance with the data sheet. The testing environment must be controlled to prevent temperature fluctuations from affecting the results.

If the number of failed units exceeds the acceptance number, the entire lot is quarantined. Sourcing teams use these metrics to track supplier performance over long-term supply agreements. This prevents the shipment of sub-standard batches across international borders.

Sourcing Implications

Procurement teams use these testing reports to release payments to the cell manufacturer. Rejection of a lot triggers a joint investigation into the root cause of the failures. The manufacturer must perform corrective actions before submitting a replacement batch.

This protects the buyer from integrating defective cells into expensive battery packs. It also establishes a transparent commercial mechanism for handling warranty claims and dispute resolution between the supply chain partners, ensuring smooth industrial operations.