Nowadays, errors during the manufacturing process of high value components are not acceptable in driving industries such as energy and transportation. Sectors such as aerospace, automotive, shipbuilding, nuclear power, large science facilities or wind power need complex and accurate components that demand close measurements and fast feedback into their manufacturing processes. New measuring technologies are already available in machine tools, including integrated touch probes and fast interface capabilities. They provide the possibility to measure the workpiece in-machine during or after its manufacture, maintaining the original setup of the workpiece and avoiding the manufacturing process from being interrupted to transport the workpiece to a measuring position. However, the traceability of the measurement process on a machine tool is not ensured yet and measurement data is still not fully reliable enough for process control or product validation. The scientific objective is to determine the uncertainty on a machine tool measurement and, therefore, convert it into a machine integrated traceable measuring process. For that purpose, an error budget should consider error sources such as the machine tools, components under measurement and the interactions between both of them. This paper reviews all those uncertainty sources, being mainly focused on those related to the machine tool, either on the process of geometric error assessment of the machine or on the technology employed to probe the measurand.

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Touch probes are commonly employed in new machine tools (MTs), and enable machining and measuring processes to occur on the same MT. They offer the potential to measure components, either during or after the machining process, providing traceability of the quality inspection on the MT. Nevertheless, there are several factors that affect measurement accuracy on shop-floor conditions, such as MT geometric errors, temperature variation, probing system, vibrations and dirt. Thus, the traceability of a measurement process on an MT is not guaranteed and measurement results are therefore not sufficiently reliable for self-adapting manufacturing processes. The current state-of-the-art approaches employ a physically calibrated workpiece to realise traceable on-MT measurement according to the ISO 15530-3 technical specification, but it has a significant limitation in that it depends on a physical workpiece to understand the performance of the systematic error contributor (ub). To this end, the aim of this paper is to propose an alternative methodology for on-MT uncertainty assessment without using a calibrated workpiece. The proposed approach is based on a volumetric error mapping of the MT prior to the measurement process, which provides an understanding of how the systematic error contributor (ub) performs. An experimental exercise is performed for a medium-size prismatic component according to the VDI 2617-11 guideline, and the results are compared with the ISO 15530-3 technical specification.

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