Form Metrology

AbstractAn intercomparison of high-accuracy roundness measurements has been carried out with the participation of thenational standards laboratories of ten European countries. The circulated artefacts were a hemispherical glass standardand a steel disc. A total of eight roundness profiles were examined, two on the hemisphere and six on the disc. Theeccentricity between external and internal surfaces…

There is an increasing demand for more accurate surface metrology instruments and for techniques which willallow complicated or large parts to be measured i f t situ. This report analyses existing and new multi-orientation andmultiprobe techniques and shows how they can be used to remove systematic and variable errors.

Many methods of measuring the out-of-roundness of nominally circular components or holes have been based,for convenience, upon some form of graphical assessment in which the inspector uses a pair of compasses, a rule and agood measure of subjective judgement. This has changed in recent years with the introduction of methods which can beimplemented in an…

Abstract The minimum zone, minimum circumscribing and maximum inscribing references (here grouped as ‘boundingreferences’) used in the measurement of roundness are investigated. Their behaviour is studied by formulating their definitions mathematically as optimization problems. The advantages of limacon references, both for accuracy under practical measurement conditions and for computational convenience, are investigated and the relationships…