What is the difference between QA and QC?
QA asks "are we doing the work the right way?" and QC asks "is this output right?". ISO 9000 treats both as parts of quality management: QA gives confidence that requirements will be met, and QC checks that they have been met.
| Quality assurance (QA) | Quality control (QC) | |
|---|---|---|
| Focus | The process | The product or service |
| Purpose | Prevent defects | Detect defects |
| Timing | Before and during the work | During and after the work |
| Typical activities | Standard work, procedures, training, process audits, supplier approval | Inspection, testing, measurement, sampling |
| Who | Everyone who runs or manages the process | Inspectors, operators doing self-checks, lab |
| Output | A capable, followed process | Accept, reject or rework decisions |
What are examples of quality assurance?
- Written standard work and work instructions for each critical step
- Layered process audits that check the standard is being followed
- Operator training and sign-off before working unsupervised
- Supplier approval and incoming material specifications
- Error-proofing (poka-yoke) so the defect cannot be made
What are examples of quality control?
- First article inspection at the start of a run or after a changeover
- In-process checks against a control plan, often on a control chart
- Final inspection and testing before dispatch
- Laboratory testing of samples against a specification
How do QA and QC work together?
QC produces the evidence; QA acts on it. When an inspection finds a defect, the product is contained and a non-conformance is raised. The repeat pattern is then traced to root cause, the process or standard is corrected, and the change is verified. Without that loop, QC only sorts good from bad and the same defects keep returning. Without QC, QA has no data to show whether the process really works.
Where QA/QC fits in daily management
The quickest way to close the loop is to put quality on the same board as safety and delivery. Failed checks, first pass yield and open non-conformances are reviewed every shift, and anything that repeats moves into structured problem solving.