Quality Management Glossary

Are you unfamiliar with a technical term in connection with quality management, or do you need a reliable definition? In the TQ glossary on this topic you will find explanations of frequently used terms from our business areas.

Alphabetical list

 A    C    I    P    Q    Z  


The term accreditation (Latin accredere, to believe) is used in various areas to describe the fact that a generally recognised authority certifies the fulfilment of a particular (useful) quality by another. Conformity assessment bodies are organisations that provide the following conformity assessment services: Testing and calibration, inspection, certification of management systems, persons (personal certification in terms of proof of qualification) and products.

A certification body is accredited when an accreditation body formally confirms that the certification body fulfils the conditions set out in e.g. standards DIN EN ISO/IEC 17021, DIN EN ISO/IEC 17024 and DIN EN ISO/IEC 17065 for the performance of assessments of management systems (e.g. quality management or environmental management), products or persons.

A testing or calibration laboratory is accredited if it meets the requirements of the DIN EN ISO/IEC 17025 standard, for example. For this purpose, the laboratory is assessed by assessors of an independent accreditation body which fulfils the DIN EN ISO/IEC 17011 standard and monitored by surveillance assessments at intervals of one to one and a half years. An inspection body is accredited if it meets the requirements of the standard e.g. ISO/IEC 17020 and an accreditation body formally confirms this.

Advance quality planning

Advance quality planning is an essential part of quality management. In order to be able to perform all tasks during the development of new products and processes as well as changes or improvements in a target-oriented and low-risk manner, appropriate quality management guidelines must be observed.
The advance quality planning process covers all steps from development to series production and is intended to ensure that products and purchased parts are available at the right time, in the right place, in the right quantity and quality.



Certification (from Latin "certus" = determined, certain, safe and "facere" = to make, create, manufacture) is a process by means of which compliance with certain requirements is demonstrated.

Certification is a sub-process of conformity assessment. Certifications are often issued for a limited period by independent certification bodies such as DQS, TÜV or DEKRA and the standards are independently or proprietarily controlled.


Integrated quality management system

The Integrated Management System combines methods and instruments for compliance with quality, environmental and occupational safety requirements in a uniform structure. Our integrated QM system meets the requirements, 

  • to the quality management according to DIN EN ISO 9001
  • to the quality management according to DIN EN 9100

in certain areas,

  • to the quality management according to DIN EN 9110
  • in certain areas,
  • to the quality management according to DIN EN ISO 13485
  • in certain areas, with the exception of requirements for sterile and implantable medical devices,
  • to the quality management according to DIN EN ISO/IEC 80079-34
  • in certain areas,
  • to environmental management in accordance with DIN EN ISO 14001
  • to energy management in accordance with DIN EN ISO 50001 at the Delling location
  • The occupational safety management system is based on OHRIS (Occupational Health and Risk Management System).

Process capability

Process capability means how well a process or its result (output) matches the requirement (customer request). With the help of the process capability index Cp, Cpk:

  • the performance of a process can be clearly described,
  • several processes with the same output can easily be compared with each other and
  • Improvements of processes can be shown.

The process capability index Cp compares the tolerance window specified by the customer with the natural dispersion of the process (±3σ).


Quality control loop or PDCA cycle

Quality control loop, also known as PDCA cycle, Demingrad, Demingloop or Shewhart cycle, is an essential basic concept of quality management in the continuous improvement process, in the development of products and services or for error-cause-analysis.

PDCA means Plan-Do-Check-Act (Plan-Exect-Verify-Adjust). The PDCA cycle is easy to use, can be used sensibly in all areas of the company and only has to be adapted to the specific task in the application. Simplicity, fast learnability, good adaptability to the most different tasks and problem definitions are the crucial advantages of the PDCA method. PDCA cycle, Deming circle, Deming wheel or also Shewhart Cycle describes an iterative three- and/or four-phase process for learning and improvement of the US-American physicist Walter Andrew Shewhart.

PDCA stands for the English Plan - Do - Check - Act, which in German is also translated as 'Planen - Tun - Prüfen - Umsetzen' or 'Planen - Umsetzen - Überprüfen - Handeln'. 


Zero-error strategy

The zero error strategy was developed in the early 1960s by the American Philip B. Crosby and describes a fault-free production in which no rejects are to be generated and therefore no reworking is necessary.

This strategy is based on Crosby's assumption that "quality" costs nothing. But it's not a gift." 

It is assumed that not the production of quality costs, but the repair of errors. The aim of the program is therefore to exclude even the smallest defects from any existing production process, i.e. already in the development phase of the product.