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The UK's most accurate calibration services for length standards

Gauge blocks (slip gauges) are among the most common length standards used in engineering. They are used to calibrate or verify the performance of a wide range of instruments or other standards ranging from micrometers and Vernier callipers to coordinate measuring machines. Before use, these standards must themselves be calibrated according to various national or international specification standards and should then be subject to an ongoing programme of re-calibration, according to the frequency of use and the required accuracy.

By offering the most accurate services in the UK, we can help you reduce your uncertainty, thereby improving process control, reliability and efficiency. We can calibrate: the central length, flatness and variation in length of gauge blocks and the thermal expansion coefficient of long gauge blocks. The majority of these services are accredited by UKAS and internationally recognised under the CIPM Mutual Recognition Arrangement.

NPL’s gauge block calibration service offers the following features:

  • measurements traceable to the national standard for length
  • interferometric calibration of central length
  • interferometric calibration of coefficient of thermal expansion (lengths over 100 mm)
  • verification of measurement face flatness and variation in length (parallelism)
  • best measurement uncertainty at a confidence level of 95 % of nm, where L is the gauge length in millimetres
  • gauges exceeding the tolerances on variation in length and flatness are highlighted on the certificate
  • phase correction of steel, tungsten carbide and ceramic gauge block sets
  • uncertainties ranging from 20 nm (shortest gauges) to 35 nm (100 mm gauges)

NPL can measure the following grades of gauge block:

  • Grades K, 0 of (BS EN) ISO 3650
  • Grades K, 0 of BS 4311 (2007)
  • Grades Calibration, Reference, 00, 0 of BS4311 (1968) and BS 888
  • Grade 1 of (BS EN) ISO 3650 (by mechanical comparison)

Note: other types of gauge blocks can be calibrated on request.

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Contact our Customer Services team on +44 20 8943 7070