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This paper proposes a quick and efficient methodology of uncertainty estimation on measurement results provided by an articulated arm coordinate measuring machine (AACMM). The methodology is highly adapted to industrial applications—a frequent use of these devices—but can also be performed in laboratories. The study stems from an actual need among coordinate measuring arm users to estimate the uncertainty associated with their equipment in specific conditions on the shop floor. It is important to mention that no simple and quick test exists currently to estimate the measurement uncertainty of results obtained with an AACMM in the conditions of the measurement site. In fact, the guidelines and studies addressing measuring machines propose protocols to verify performance or to evaluate uncertainties associated with measurement results, but these protocols are laboratory-type tests (carried out after purchase, re-calibration, etc) and usually take hours to complete.

In order to verify the performance of articulated arm coordinate measuring machines, the standards/guidelines that address this topic require the use of different length artefacts. For instance, the volumetric test of ISO 10360-12:2016 requires measuring five calibrated lengths in seven directions (three horizontal, three diagonal and one vertical). If a ball bar is used to perform the test with each sphere measured with five points, then the test requires measuring 1050 points (7 directions × 5 lengths × 2 spheres × 5 points × 3 repetitions).The aim of this paper is to optimize this type of test and adapt it to industrial environments, in terms of ergonomics and time of measurement. For this purpose, two solutions merging the concept of segmented ball bars with the concept of kinematic seats are proposed. The first solution involves using a passive self-centering probe and a regular segmented ball bar (with joining spheres). The second novel solution involves replacing the joining spheres of the ball bar by spherical mounts containing kinematic seat inserts and a regular spherical probe. The kinematic seats in both solutions are designed in a way to optimize their rigidity, machinability and their uncertainty of measurement. Both proposed solutions reduce considerably the time of measurement. In addition, it will be demonstrated in the paper that the first solution presents the advantage of decreasing the uncertainty of measurement whilst the second solution might increase it lightly, compared to a regular ball bar measured with a regular spherical probe.

If the problems related to the parts and measurement strategy of Coordinate Measuring Machines (CMMs) are not taken into consideration, temperature variations become the main source of measurement uncertainties. Indeed, they may cause variations in geometry as well as reference point drift. The effect of drift is sometimes minimized by CMM users and is not well quantified in general. The aim of this paper is to present a physical method to determine the evolution of CMM geometry and drift which is based directly on CMM temperature variations and construction parameters, i.e. the position of the axes measurement scales and reference points of each axis. The method is applied to a Zeiss CMM Contura G2. The consequences of these CMM evolutions are simulated in the measurement of a sphere generated by a Renishaw Machine Checking Gauge. The proposed method falls within the framework of an uncertainty assessment methodology performed by multi-level Monte Carlo simulation, where the first level corresponds to the characterization of the CMM evolution.

Composite materials are increasingly used in 3D metrology devices. Their use is justified by their interesting mechanical properties including their low density and good rigidity but especially their low coefficient of thermal expansion. In fact, in order to improve production efficiency, companies nowadays integrate more and more control equipment directly in situ. These are then subject to thermal variations. The use of composite materials is an interesting approach. However, in some cases, the lack of knowledge of their coefficient of thermal expansion and their behavior might increase measurement uncertainties. The objective is to study the thermal behavior of a carbon tube alone and the same tube with aluminium fixing elements at its extremities, in order to determine the coefficients of expansion of the carbon alone and to quantify the influence of the fixation with aluminium elements. This experiment makes it possible to directly compensate the dimensional variations of the metrological structure depending on the temperature variations and thus to limit measurement uncertainties. The thermal expansion coefficients of the carbon tube and its assembly are determined by measuring relative variations in height with a ZERODUR® reference bar. The whole is positioned in a climatic chamber. *