Quality control is performed at various stages.

1. Inspection prior to production: Normally, one unit or piece will be produced and, if it passes inspection, production run will proceed.

2. Inspection in-process: The inspections will be made at intervals during the production process.

3. Inspection after production: For many, this is considered as the final inspection and testing stage. A sample or 100% of the finished products will be inspected and tested.

4. Inspection prior to shipping: The orders placed by a customer will be inspected and will not be shipped until the final inspector has cleared them.