Quality assurance vs quality control (QA/QC): what is the difference?
The two terms are often confused, including in factories. For an importer, the distinction tells you what to ask of the supplier, and what to check yourself.
Quality assurance (QA) organises manufacturing so that defects do not appear: procedures, training, audits. Quality control (QC) checks the product to detect defects: inspections, tests, AQL sampling. With a Chinese supplier you need both: a factory audit for QA, an inspection of every order for QC.
Two definitions, two goals
ISO 9000, which sets the vocabulary of quality management, distinguishes two notions:
- Quality assurance (QA) aims to provide confidence that quality requirements will be fulfilled. It concerns the organisation: procedures, skills, equipment, control of suppliers.
- Quality control (QC) aims to fulfil those requirements. In practice it checks products: measurements, tests, inspections.
In other words, quality assurance prevents defects and quality control detects them. One looks at the process, the other at the product.
QA and QC at a glance
| Quality assurance (QA) | Quality control (QC) | |
|---|---|---|
| Goal | Stop defects from appearing | Find defects before they reach the customer |
| Concerns | The process and the organisation | The product and the lot |
| When | Before and during production | During and after production |
| Tools | Procedures, quality plan, training, calibration, audits, supplier assessment | Inspections, lab tests, AQL sampling, sorting |
| Result | A system that produces consistently | A lot accepted or rejected |
| At LPI | Initial factory evaluation, technical audit, supplier quality manager | Inspections at every stage, lab testing |
An example: a wooden chair
Take an order of chairs made in China.
- On the quality assurance side, the factory checks the moisture content of the wood on receipt, dries lots above the limit, trains operators in assembly, calibrates its instruments and follows a written control plan. A factory audit checks that all this exists and works.
- On the quality control side, the inspector measures moisture and checks assembly and stability on an AQL sample of the finished order, and a laboratory tests strength under the standard that applies to seating (EN 1728, for example).
If quality assurance is weak, quality control will find defects, order after order. If there is no quality control, nobody will know the system slipped on that particular lot.
What the importer can do on each side
You do not run your supplier’s quality system, but you can assess it and check its output.
Assessing the supplier’s quality assurance
A technical factory audit, based on ISO 9000 principles, examines the factory profile, the quality team, equipment and the quality system: purchasing, design control, storage, incoming inspection, in-process control, testing and continuous improvement. Before a first order, a lighter initial evaluation already checks that the factory has the capacity to meet your requirements.
Controlling the quality of each order
Inspections follow the life of the order: initial production check, during production inspection, final random inspection, container loading supervision. Lab tests prove compliance with standards, which an inspection cannot do. The factory’s quality department also runs its own checks; they do not replace an independent eye, as our guide inspect yourself or outsource explains.
Where to start?
- New supplier: assess the factory before paying the deposit (quality assurance), then inspect each order (quality control). Start by checking the supplier in public registers, for free.
- Established supplier: after several compliant orders in a row, you can space out checks or keep only the final inspection.
- Repeated defects: tightening control is not enough; you have to trace the cause in the factory’s quality system, with an audit and a corrective action plan.
Traceability links the two: it ties each lot to the checks it went through. That is the subject of our guide quality control and traceability. For the big picture, read our complete guide to quality control in China.
Frequently asked questions
What do IQC, IPQC and OQC mean in a Chinese factory?
They are the stages of the factory’s internal quality control. IQC (incoming) checks materials and components on receipt, IPQC (in-process) checks manufacturing on the line, and OQC (outgoing), sometimes called FQC (final), checks finished products before they leave. Ask to see their records during an audit.
Does an ISO 9001 certified factory still need to be inspected?
Yes. The certificate shows that a body has audited the factory’s quality management system, not that your lot complies. Check that it is valid and covers the site and activity that make your product, then inspect your orders as you would with any supplier.
Is quality control part of quality assurance?
In ISO 9000, the two are distinct components of quality management. In practice they feed each other: defects found during control show where the factory’s system needs correcting, and a good system reduces the number of defects found during control.
Assess your supplier, control your orders
A technical factory audit for quality assurance, inspections of every order for control: LPI covers both.