AQL and OQL Supplier Audit

AQL and OQL

In the context of audits and quality control for AQL and OQL, AQL (Acceptable Quality Level) and OQL (Outgoing Quality Level) measure product quality and performance during inspection processes. Here’s a detailed explanation of each term:

AQL (Acceptable Quality Level)

• Definition:
  AQL specifies the maximum percentage or proportion of defective items allowed during random sampling in quality inspections. It sets a clear threshold for tolerable defects in a batch.
• Purpose:
  AQL ensures the batch meets predefined quality standards and guides decisions on whether to accept or reject a lot.
• Usage:
  Inspectors use AQL in incoming quality control (IQC) processes to check items before they enter production or distribution.
• Example:
  If the AQL is set at 2.5%, no more than 2.5% of the sampled items can be defective for the batch to pass inspection.

OQL (Outgoing Quality Level)

• Definition:
  OQL indicates the proportion of defective items in a batch after the final quality inspection, just before shipping to customers. It reflects how effectively the inspection and manufacturing process maintained quality.
• Purpose:
  OQL represents the quality of goods delivered to customers and evaluates the reliability of quality assurance systems.
• Usage:
  Inspectors commonly use OQL in final product inspections (FQC) to assess the overall quality before shipment.
• Example:
  An OQL of 1% means only 1% of the outgoing batch is defective.

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Key Differences Between AQL and OQL

Aspect	AQL	OQL
Stage of Use	Incoming quality inspection (IQC)	Outgoing quality inspection (FQC)
Focus	Acceptable defect level for the batch	Defect level of the final shipped product
Perspective	Prevents defective products from entering production	Reflects actual quality delivered to customers
Primary Purpose	Sets a standard for batch acceptance/rejection	Measures final product quality

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Which One is Better – AQL and OQL?

• Depends on Context:
  Neither is inherently “better,” as they serve different purposes.
  • AQL is critical for manufacturers and suppliers to maintain internal quality standards and reduce waste.
  • OQL is essential for maintaining customer satisfaction by ensuring high-quality outgoing products.
• Holistic Approach:
  A robust quality control system uses both AQL and OQL to balance production efficiency with customer satisfaction.