Marcin Krawczyk

Determination of the uncertainty of the measurements performed by coordinate measuring machines

Abstract Today many different systems are working in accordance with the idea of coordinate measuring techniques. It is possible to use the same measuring software with optical or contact coordinate systems as well as with a 3D scanners. This gives the opportunity to use different measuring systems for the same tasks. Consequently, it is possible to build faster and more efficient techniques for controlling the production. For example: a fast check of car body production with 3D scanner systems and once per shift accurate measurement of the same element with reference Coordinate Measuring Machines. The main purpose of measurements in industry is the assessment of the conformity or nonconformity of the production with the specification. The specification can be written in classical paper documentation or saved in CAD-file. Never-mind how specification is written or saved, the uncertainty of the measurement should be taken into consideration, according to the ISO 14253-1 guideline. In the case of a supplier – to his benefit, by extending the area of conformity and in the case of production control – by reducing the area of conformity. Evaluation of the coordinate measurement accuracy is very complicated task, especially elaborating of one method for all Coordinate Measuring Systems. Until now, majority of methods focus only on the Coordinate Measuring Machines. ISO 15530 family of standards can be noticed in this area, however, many problems still remain unsolved.

The application of spherical standards for the evaluation of the accuracy of mapping shape in computed tomography

Abstract Anatomical structures are characterized by free surfaces, and most are in lobed and pseudo-spherical shapes. The aim of this article is to analyze selected procedures for accuracy assessment of the shape and dimensions of these structures using certified sphere and Ball Bar standards and to propose metrology parameters facilitating comparison of diagnostic devices. The spherical standard of various materials and Ball Bar standards with various distances between spheres centers can be a tool for evaluation of computed tomography metrology applications. Errors in geometry mapping can be identified on the basis of standardized control systems used in coordinate measuring techniques.