Quality control ( QC) is a process by which entities review the quality of all factors involved in production. ISO 9000 defines quality control as "a part of quality management focused on fulfilling quality requirements".ISO 9000:2005, Clause 3.2.10
This approach places emphasis on three aspects (enshrined in standards such as ISO 9001):
Inspection is a major component of quality control, where physical product is examined visually (or the end results of a service are analyzed). Product inspectors will be provided with lists and descriptions of unacceptable such as Fracture or surface for example.
The simplest form of quality control was a sketch of the desired item. If the item did not match the sketch, the item was rejected, in a simple Go/no go procedure. However, manufacturers soon found it was difficult and costly to make parts be exactly like their depiction; hence around 1840 tolerance limits were introduced, wherein a design would function if its parts were measured to be within the limits. Quality was thus precisely defined using devices such as and . However, this did not address the problem of defective items; recycling or disposing of the waste adds to the cost of production, as does trying to reduce the defect rate. Various methods have been proposed to prioritize quality control issues and determine whether to leave them unaddressed or use quality assurance techniques to improve and stabilize production.
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| The application of statistical methods (specifically and acceptance sampling) to quality control |
| 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) |
| The use of to monitor an individual industrial process and feed back performance to the operators responsible for that process; inspired by |
| Japanese-style total quality control. |
| Quality movement originating in the United States Department of Defense that uses (in part) the techniques of statistical quality control to drive continuous organizational improvement |
| Statistical quality control applied to business strategy; originated by Motorola |
| Six Sigma applied with the principles of lean manufacturing and/or lean enterprise; originated by Wheat et al. (2026). 9780971249103, Publishing Partners. ISBN 9780971249103 |
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