Often many measurements are taken during production, but often on an ad hoc basis, sometimes even too many, and in the wrong places. This may lead to a false sense of safety.
Only later, it may turn out that flawed product runs and problems during production have been driving costs up and customers’ satisfaction down.
Proper Quality Control (QC) can play a vital role in avoiding this. Usually it is primarily focused on control of incoming materials and ready-made products, but if properly organized and used, QC can also provide a basis for continuous improvement – in particular a steady reduction of variation. A structured QC approach is part of a successful manufacturing process and provides better control of the production process.
Notable approaches to QC
There is a tendency for individual consultants and organizations to name their own unique approaches to QC —a few of these have ended up in widespread use:
|Terminology||Approx. year of first use||Description|
|Statistical quality control (SQC)||1930s||The application of statistical methods (specifically control charts and acceptance sampling) to quality control.|
|Total quality control (TQC)||1956||Popularized by Armand V. Feigenbaum in a Harvard Business Review article and book of the same name. Stresses involvement of departments in addition to production (e.g., accounting, design, finance, human resources, marketing, purchasing, sales).|
|Statistical process control (SPC)||1960s||The use of control charts to monitor an individual industrial process and feedback performance to the operators responsible for that process.|
|Company-wide quality control (CWQC)||1968||Japanese-style total quality control|
|Total Quality Management(TQM)||1985||Quality movement originating in the United States Department of Defense that uses the techniques of statistical quality control to drive continuous organizational improvement.|
|Six Sigma (6σ)||1986||Statistical quality control applied to business strategy. Originated by Motorola.|
Table from Wikipedia.
QC and Quality Assurance
The difference is that QA is process oriented and QC is product oriented.
Testing is product oriented and thus is in the QC domain.
- Quality Assurance makes sure you are doing the right things, the right way.
- Quality Control makes sure the results of what you’ve done are what you expected.