MetrologyMetrology is the science of measurementDimensional metrology is that branch of Metrology which deals with measurement of dimensions of a part or workpiece (lengths, angles, etc.)Dimensional measurements at the required level of accuracy are the essential link between the designers intent and a delivered product.

Aspects of MetrologyReference standard metrologyEngineering Metrology

Basic Measurement DevicesSurface PlatesTest StandsDial GagesMicrometers and VerniersGage Blocks

Dimensional Metrology NeedsLinear measurementsAngular measurementsGeometric form measurementsRoundnessStraightnessCylindricityFlatness, etc

Dimensional Metrology NeedsGeometric relationshipsParallel, perpendicular, etc.Concentric, runout, etc.Controlled surface texture

Communicating Dimensional Metrology NeedsGeometric Dimensioning and Tolerancing (GDT)The language of dimensional metrologyStandard symbols, etc., on part drawings.

Specification of Linear Tolerances

Angular Specifications

Angular Tolerances

Flatness Specification

Flatness Tolerances

Straightness Specification

Straightness Tolerance

Roundness SpecificationRoundness applies to every section

Roundness Tolerances

Surface Profile Without Datums

Line Profile Without Datums

Surface Profile with DatumsProfile of a line with datums is similar

Surface Profile with Datums

Cylindricity Specifications

Cylindricity Tolerances

Surface Texture Specification

Surface Texture

Perpendicularity Specification

Perpendicularity Measurements

Parallelism Specification

Parallelism Measurements

Concentricity Specification

Concentricity Tolerances

Concentricity Measurements

Concentricity Measurements

Circular Runout Specifications

Circular Runout Tolerances

Total Runout Specifications

Total Runout Tolerances

Position Specifications

Position Tolerances

Simulated Datum

Datum Selection