Dimensional metrology calibration services

What We Offer

Dimensional and related calibrations are performed at 20 °C. Our dimensional metrology facilities are temperature-controlled clean rooms maintained at 20.00 °C ± 0.05 °C with relative humidity controlled to 40 ± 2%. The dimensional metrology group at the NRC offers calibration services in the fields of:

Optical Frequency and Wavelength standards are maintained by the Frequency and Time group.

Please contact us for quotes, custom and consultation services.

Angle Standards

Calibration of angle standards can be done at the NRC as custom services. Examples of angle standards include:

• Angle gauge blocks
• True Squares
• Polygons

Contact NRC dimensional metrology to discuss calibration requirements and pricing.

Coordinate Metrology

Calibration of reference objects and dimensional measurement of finished parts via coordinate measuring machine (CMM) are available as custom services. Some examples of objects which can be measured:

• Step Gauges
• Ball Bars
• Optical Dot Plates
• Master Parts

The CMM has an effective working volume of 700 mm x 700 mm x 400 mm and has the capability of carrying either a high-precision analogue probe for tactile measurements or a CCD-based video probe for non-contact measurements.

Contact NRC dimensional metrology to discuss calibration requirements and pricing.

Diameter Standards

Plain cylindrical diameter standards (i.e. rings and plugs) in the range 10 mm to 100 mm are calibrated by comparison to reference gauge blocks using a high-precision coordinate measuring machine (CMM). The calibrated diameter is a single 2-point diameter taken at the mid-plane of the gauge and usually aligned with respect to the manufacturers' markings on the top surface of the gauge. The orientation of the diameter to be measured must be confirmed with the NRC dimensional metrology technical contact. For high-quality cylindrical gauges in good condition, the expanded uncertainty is U = Q[0.17, 0.00088L] µm, k = 2.01 where L is in mm (see ^{note 1}). For example, a ring gauge of 50 mm nominal diameter can be calibrated with an associated uncertainty as low as 0.18 µm.

Additional 2-point diameter measurements may be requested and are priced according to the fees listed below.

Cylindrical diameter standards which are outside the range 10 mm to 100 mm may also be calibrated; please contact NRC dimensional metrology to discuss.

Diameter standards which are not cylinders (e.g. ring/disc segment gauges, spheres), may also be calibrated; please contact NRC dimensional metrology to discuss calibration requirements.

End standards (gauge blocks and length bars)

End standards are calibrated using the NRC gauge block interferometer. This type of calibration is done using the method of exact fractions and three laser wavelengths.

Gauges are first inspected to ensure that the end surfaces are flat, parallel, and will wring to a reference optical flat. Gauge blocks up to 100 mm are calibrated in a vertical orientation, wrung to an optical flat. Length bars over 100 mm and up to 1000 mm are calibrated one at a time in a horizontal orientation, supported at their airy points and with a small optical flat wrung to one end.

Gauges of various materials can be calibrated, such as steel, carbides (e.g. Croblox^TM), and ceramics. Typically only the highest grades of gauge blocks are suitable for calibration by interferometry. Calibration uncertainty is commensurate with the quality of the gauges and under optimal conditions is limited to U = Q[25,0.1L] nm at k = 2 for steel gauge blocks, where L is the length of the gauge in mm (see ^{note 1}). For example, for a 100 mm steel gauge block, the NRC can offer uncertainty as low as 27 nm, and for a 500 mm steel length bar, the NRC can offer uncertainty as low as 56 nm.

Lower-grade gauges or those in poorer condition should be referred to an accredited calibration laboratory. The Calibration Laboratory Assessment Service directory may be used to find a suitable service provider.

Roundness Standards

Using a high precision stylus-type roundness instrument, out-of-roundness of artifacts with a circular cross section (spheres, hemispheres, rings and plugs) can be calibrated with uncertainties as low as U = 4.8 nm at k = 2.02 (see ^{note 1}). This high accuracy calibration is performed using an error separation technique. The uncertainty of the calibration depends on the quality of the artifact, so this technique is recommended for high quality artifacts only.