Dimensional Measurements
As well as offering measurement services to customers, the group also undertakes research work necessary to support, maintain and develop these services and standards. This places the group in the unique position of having direct access to national standards and calibration equipment of the highest calibre, as well as having a wide range of expertise high-accuracy dimensional measurement.
The Dimensional group has a wide range of equipment including coordinate measuring machines, surface profilometers, interferometers, scanning probe microscopes as well as bespoke instruments designed and built at NPL. This equipment and expertise are available to customers through the use of measurement and consultancy services.
Dimensional Measurements research
Large-scale metrology refers to measurement of objects or features of perhaps a metre or more in size.
Dimensional Measurements products & services
- NPL has several CMM’s suited for different sizes of components.
- Calibration service for dimensional measurement of artefacts and components.
- Calibration service for dimensional measurement of artefacts and components.
- NPL offers calibration services for both internal and external diameter standards and roundness measurements.
- A three day training course introducing measurement knowledge focusing upon dimensional techniques.
- A four day training course for those who have a good basic understanding of measurement principles gained through the Level 1 training course.
- Calibration of length standards such as gauge blocks, length bars and step gauges.
- Coventry University, with NPL's assistance, has launched the UK's first ever Foundation Degree in Metrology.
- Measurement capabilities provided by the Freeform Centre.
- Efficiency of aero engines, drag reduction for automotive bodies and increased life span of prosthetics are just some examples of the gains potentially achievable with suitable advances in freeform manufacture.
- NPL has three fringe projection systems for the measurement of components and FreeForm surfaces.
- NPL has the UK's most accurate calibration services for the measurement of engineering length standards.
- A high-accuracy calibration service for spheres and hemispheres.
- NPL has increased its micro co-ordinate metrology capabilities in direct response to the extreme demands of quality assurance for the measurement of size, form and position of microsystem parts.
- Laser trackers are polar coordinate measuring systems capable of high accuracy measurements over long distances, for example the system used by NPL can measure 40m distances to within ± 60mm.
- Calibration of thermal expansion coefficient of length bars and long gauge blocks.
- Calibration of length bars and long gauge blocks by interferometry.
- NPL provides a one-stop service for the characterisation of the form and texture of surfaces through an extensive range of facilities.
- NPL provides traceable measurements of surface texture with an expanded uncertainty (95% confidence) of 1.3 nm.
- NPL provides dimensional measurement facilities and standards for industries requiring accurate measurements using non-contact optical instrumentation.
- NPL offers a range of services devoted to supporting non-contact dimensional measurements.
- NPL offers a service to calibrate the form of optical flats up to 300 mm in diameter.
- A two day training course for users of large volume metrology systems.
- NPL offers a range of services in support of accurate ophthalmic measurements including the calibration of customer supplied reference lenses with measurements based on ISO 9342:1996.
- NPL designs and calibrates a range of optical scales and reference patterns for quantitative microscopy, image analysis and non-contact measurement systems.
- Measurement service for tapered screw thread gauges.
- Pitch reference screw measurement.
- NPL has developed a step gauge calibration system which uses laser interferometry to achieve the best accuracy for calibration of step gauges in the UK. Step gauges up to 1500 mm long can be calibrated.
- Laser trackers are polar coordinate measuring system capable of high accuracy measurements over long distances, for example the system used by NPL can measure 40m distances to within ± 60mm.
- NPL provides services for the characterisation of the form and texture of micro or nano-scale surface features using our extensive range of facilities.
- Measurement service for surface texture.
Dimensional Measurements publications
- Good Practice Guides in Dimensional Metrology and related areas are now available.
- Information about the MOY/SCMI specifications for download.
- Interchangeability and quality of fit of nuts, bolts, and other screwed fasteners e.g. threaded pipe joints, require precision in manufacture as monitored by screw gauges. Methods of measurement have been developed continuously at NPL over 70 years and are described in NPL Notes on Screw Gauges.
- In some situations.
- Check plugs and parametric measurements are not mutually exclusive. It is NPL's opinion that for checking master gauges (i.e. not products) both check plugs and parametric measurements have their place.
- To some degree yes. Ideally, the reflectivity of both the reference and test surface should be equal to give maximum contrast fringes.
- There are many good books and in addition NPL produces a range of Good Practice Guides relating to dimensional metrology.
- No. Since 1983 the metre has been re-defined in terms of the speed of light and is realised using laser wavelengths.