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Glossary

Here you will find explanations of technical terms, abbreviations, names, and concepts related to quality management in a production environment.

37 terms

Annotation: Arbitrary information bound to a specific entity, for example an operator name bound to a particular measurement value, or a drawing number bound to a specific product. Other words with a similar meaning are tracefield and metadata.
CMM: Coordinate Measuring Machine (CMM). A machine that automatically measures multiple measurement points on a part, guided by coordinates from the part's drawing.
Cp: Capability index (Cp, process capability) for a stable process. Indicates how many times the spread fits within the tolerance. A high Cp means small spread and therefore a good process. A guideline is typically Cp > 1.33, corresponding to 4 sigma. Formula: Cp = (USL-LSL)/(6*s) where s = Rbar*d2.
Cpk: Corrected capability index (Cpk, process capability index) for a stable process, corrected to include the centering of the distribution. A high Cpk means small spread and good centering around the target value. Guideline: Cpk > 1.33 (4 sigma). Formula: Cpk = min(USL-Xbar, Xbar-LSL)/(6*s).
Digitalisation: Replacing paper forms, automating manual routines, and eliminating administrative tasks and distribution steps, as well as offering improved information supply and accessibility regardless of time and place.
Capability: See Cp, Cpk, Pp, and Ppk.
Failure Mode and Effect Analysis: See FMEA.
FMEA: Failure Mode and Effect Analysis. A tool used during the product and production development phases with the aim of identifying potential failure modes in good time.
Gage R&R: Gage Repeatability and Reproducibility. The combined estimate of repeatability and reproducibility for a measurement system, and a measure of the measurement system's capability. Repeatability is the variation when one operator measures the same dimension multiple times with the same instrument. Reproducibility is the variation when multiple operators measure the same dimension. Gage R&R is part of MSA.
Industry 4.0: An umbrella term for technologies and concepts within automation, process industrial IT, and manufacturing technologies. Each product in the production chain carries information about where it is going and how, so that the factory can organise itself. The goal is shorter changeover and lead times, fewer errors, and more flexibility.
Quality Assurance: Systematic quality work that assures the quality of the objects being assured. An organisation develops, documents, and follows its processes and uses various tools as support.
Metadata: See Annotation.
MM: See CMM.
MSA: Measurement System Analysis. A method for determining how much the variation within the measurement system contributes to the total variation of the process. MSA includes, among other things, Gage R&R.
Target value: The value aimed for in a process. In a good process, the mean value is at the target value and the spread is small.
Nom: See Nominal value.
Nominal value: The value from which the tolerance limits are specified. If the tolerance interval is 3.0 ± 1.0, the nominal value is 3.0. Should not be confused with target value, although they may coincide.
Pp: Performance index (Pp, process performance) for an unstable process. Indicates how many times the spread fits within the tolerance. Guideline: Pp > 1.67 (5 sigma). Formula: Pp = (USL-LSL)/(6*sigma).
Ppk: Corrected performance index (Ppk, process performance index) for an unstable process, corrected to include the centering of the distribution. Guideline: Ppk > 1.67 (5 sigma). Formula: Ppk = min(USL-Xbar, Xbar-LSL)/(3*sigma).
Process control: See SPC.
Production: A measurable result of some form of manufacturing, of a good or a service.
Production monitoring: Systematic control of the manufacturing process so that production can be carried out according to plan, to facilitate management and provide feedback in the form of production data.
R: Range in a subgroup, i.e. the difference between the largest and smallest value in the subgroup.
Rbar: The mean of the ranges across all subgroups. See R.
Rmax: Upper control limit in the R-chart. See Xbar and R-chart.
sigma: σ, standard deviation. An estimate of how much measurement values are spread from the mean. Used primarily when the measurement values are normally distributed.
SPC: Statistical Process Control. Makes it possible to produce parts according to the zero-defect principle by detecting abnormal variations and wear trends. Uses statistical methods to describe, control, and visualise processes.
SQC: Statistical Quality Control. Statistical methods used to measure, monitor, control, and improve quality.
Statistical Quality Control: See SQC.
OEE: Overall Equipment Effectiveness, a key metric for measuring production efficiency. A: Availability (proportion of planned operating time used for production). P: Performance (proportion of products produced compared to plan). Q: Quality (proportion of what was produced that does not need to be scrapped or reworked). OEE = A*P*Q.
Tracefield: See Annotation.
LSL: Lower Specification Limit, also called the lower tolerance limit. Can be absolute or relative to a nominal value. See also USL.
X: Denotes a single measurement value.
Xbar: The mean of all measurement values or of the measurement values in a subgroup. See X.
Xdbar: The mean of all subgroups' Xbar values. See Xbar.
UCL: Upper Control Limit.
USL: Upper Specification Limit, also called the upper tolerance limit. Can be absolute or relative to a nominal value. See also LSL.