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Size tolerancing revisited: A basic notion and its evolution in standards

Published

Author(s)

Vijay Srinivasan, Edward P. Morse

Abstract

Size is a fundamental descriptor of objects – it allows us to quantify 'how big' objects are, and to compare and classify objects based on this notion. In the world of ISO GPS (Geometrical Product Specification and Verification), size is defined much more narrowly: it is restricted to features of size, and the methods of inducing size values from an actual workpiece are strictly controlled. The release of ISO 14405-1:2010 has introduced a rich new set of size specification modifiers, which includes two-point and spherical local sizes, least squares, maximum inscribed and minimum circumscribed associations, as well as calculated diameters (inferred from the circumference, area, or volume of the feature of interest). Further modifiers allow the specification of statistics of local size measurements, such as maximum, minimum, range, average, and others. This paper will present ‘size’ as a fundamental engineering notion from several viewpoints and trace its evolution in engineering drawings. It will then discuss the implications of the use of the recently-standardized size modifiers in engineering design, and investigate the issues that may arise in the application and interpretation of these extensions to size. [Reprints and permissions: sagepub.co.uk/journalsPermissions.nav; DOI: 10.1177/0954405412470418; pib.sagepub.com]
Citation
Proceedings of the Institution of Mechanical Engineers Part B-Journal of Engineering Manufacture
Volume
227
Issue
5

Keywords

standardization, ISO, GPS, size tolerances, design intent

Citation

Srinivasan, V. and Morse, E. (2013), Size tolerancing revisited: A basic notion and its evolution in standards, Proceedings of the Institution of Mechanical Engineers Part B-Journal of Engineering Manufacture, [online], https://doi.org/10.1177/0954405412470418 (Accessed February 28, 2024)
Created May 13, 2013, Updated January 27, 2020