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UKAS (NAMAS) Accredited Capability
Precision measurement of a 3 line calibration glass
The Talyrond 73 UHPR is the most accurate
roundness instrument available
Roundess
The glass hemisphere
is a high precision standard used to both calibrate and evaluate the performance
of roundness measuring instruments.
By
using exclusive measuring techniques, the UKAS (NAMAS) laboratory calibrates the
hemisphere to a resolution of 1 nanometre, with an uncertainty of measurement
of 5 nanometres.
The
resulting certificate includes a polar plot of the profile of the measured plane,
which allows the user to accurately ascertain any departures from roundness by
comparing the calibrated plot against that obtained on their Talyrond system.
Assessment of the accuracy of a straightness and cylindricity measuring instrument can be verified by means of a precision cylinder, which will have been calibrated using a mechanical reversal technique such that the pure error in the straightness of the cylinder is plotted . The result obtained on the users system can then be compared the calibrated profile on the UKAS (NAMAS) certificate.
For more details, contact Pat Kilbane on +44 (0) 116 246 3104 or e-mail calibration@taylor-hobson.com
The UKAS (NAMAS) laboratory is able to measure all of the parameters associated with surface texture, including German and French derivatives.
Roughness standards are calibrated to an uncertainty of Ra which is the lowest currently available from any laboratory accredited by UKAS.
A tungsten carbide sphere is used to calibrate the Form Talysurf Series range of instruments. It's radius, roundness/sphericity and surface texture are each calibrated to provide a high precision multi-purpose standard.
The ball may be used to calibrate the instrument, or as a "confidence gauge", to ensure its accuracy is maintained.
The laboratory is currently accredited for the calibration of spheres, plugs, rings, and length bars. Temperature corrected measuring techniques are used in conjunction with sophisticated control software to achieve uncertainties down to ± 0.5mm
The basic methods employed for angle measurement are either the accurate division of a circle, by using a high precision index table, or the generation of a known angle by means of a precision sine bar (angle generator) or indexing head (rotary table) .
The precision index table is used in conjunction with an autocollimator for the calibration of a polygon. Any errors found in the polygon are tabulated on the UKAS (NAMAS) certificate. By taking these errors into account during its use, a higher accuracy of measurement can be achieved.
A small angle generator jointly designed by Taylor Hobson and NPL is used in conjunction with traceably calibrated gauge blocks for the calibration of an autocollimator. Both progressive and periodic errors are measured and certified. Knowledge of these errors enables more precise use of the instrument by the operator.
Block levels, clinometers and electronic levels are calibrated by use of sophisticated sine lever techniques. For example, a Talyvel 4 electronic level is calibrated using a Taylor Hobson small angle generator. The user benefits from the ability to compensate for known errors when using the instrument.
The line of sight and displacement errors of a Micro Alignment Telescope are assessed by viewing into fixed focus and variable focus collimators . Deviations are recorded on the UKAS (NAMAS) certificate, providing the means for more accurate measurement. Micrometer and focussing accuracies are also verified using traceably calibrated scales and artifacts.
Calibration
