Good practices and uncertainty assessment process on AACMM

Abstract

International audienceThis paper presents a methodology of evaluating the performance of Articulated Arm Coordinate Measuring Machines (AACMM) for general acceptance-based on the manufacturer's specifications, and on site-based mainly on the application requirements. The first part of this paper takes stock of ISO 10360-12: 2016 standard, which defines the tests that the AACMM user should perform to validate or not the performance of his machine. The various tests recommended by the standard are analyzed and their practical usefulness is explained. In the second part of the paper, an on-site uncertainty estimation methodology is proposed. The interest of the on-site verification methodology proposed is illustrated by actual tests with different artifacts. Moreover, an Aimess Products patented innovative removable tetrahedral artifact [1], highly adapted for quick on-site verification is presented as well. The advantages and disadvantages of the commonly used length artifacts are discussed. No one of the available AACMM standards addressed the on-site verification topic. The importance of the proposed methodology is to enable the user to assess the uncertainties in the measurement site, which may be actually different from the uncertainties of the AACMM in the optimal environmental conditions, provided by the manufacturer. The aim of the on-site verification tests is not providing an exact estimation of the uncertainty of measurement; it is rather giving an order of magnitude of the uncertainty in the site. The overall aim of these tests is to be able to detect if there are any important issues in the site and to evaluate if we are far from the required tolerance