qualitycontrol

Quality control (QC) is the set of operational techniques and activities used to fulfill quality requirements for a product or service. QC typically involves reviewing processes and outputs to identify defects or deviations from specifications through inspections, measurements, and testing at various stages of production. The aim is to detect problems before final delivery and to verify that outputs meet defined criteria.

Quality assurance (QA) is the broader, process-oriented part of quality management, designed to prevent defects by improving the production process. QC is often described as reactionary to defects and is a component of QA; in practice the two are complementary.

Common QC methods include statistical process control, acceptance sampling, and a range of measurement techniques. Tools such as control charts, sampling plans, and failure mode analysis help determine when to stop production, adjust processes, or reject items. Measurement systems analysis ensures measurement accuracy and comparability across inspectors and instruments.

Quality management frameworks such as ISO 9001, Six Sigma, and Lean emphasize systematic, data-driven approaches to reduce variation and improve quality. Quality costs, including prevention, appraisal, and costs of poor quality, are used to justify investment in QC and related activities. The Plan-Do-Check-Act cycle underpins continual improvement in QC programs.

In practice, QC contributes to product reliability, regulatory compliance, and customer satisfaction by ensuring that outputs consistently meet defined standards and performance criteria across the value chain.