sewing machine parts factory in Dresden, East Germany, 1977.]] Quality control, or QC for short, 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 an emphasis on three aspects (enshrined in standards such as ISO 9001):
- Elements such as controls, job management, defined and well managed processes, performance and integrity criteria, and identification of records
- Competence, such as knowledge, skills, experience, and qualifications
- Soft elements, such as personnel, integrity, confidence, organizational culture, motivation, team spirit, and quality relationships.
History and introductionModern humans are distinguished from other species by their extensive use of tools to control and adapt to their surroundings. Early stone tools such as anvils had no holes and were not designed as interchangeable parts. Mass production established processes for the creation of parts and system with identical dimensions and design, but these processes are not uniform and hence some customers were unsatisfied with the result. Quality control separates the act of testing products to uncover defects from the decision to allow or deny product release, which may be determined by fiscal constraints. For contract work, particularly work awarded by government agencies, quality control issues are among the top reasons for not renewing a contract. The simplest form of quality control was a sketch of the desired item. If the sketch did not match the item, it 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 plug gauges and ring gauges. 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.
Notable approachesThere is a tendency for individual consultants and organizations to name their own unique approaches to quality control—a few of these have ended up in widespread use:
In project managementIn project management, quality control requires the project manager and/or the project team to inspect the accomplished work to ensure its alignment with the project scope. In practice, projects typically have a dedicated quality control team which focuses on this area.
- Analytical quality control
- Corrective and preventative action (CAPA)
- Eight dimensions of quality
- First article inspection (FAI)
- Good Automated Manufacturing Practice (GAMP)
- Good manufacturing practice
- Quality assurance
- Quality management framework
- Standard operating procedure (SOP)