Compensation of CMM geometrical errors using Laser Tracer – the pilot experiment at a CMM manufacturer

Market requires products with increasingly high levels of accuracy, therefore it arises from the quality department the need to measure them with more performing Coordinate Measuring Machines (CMMs). These machines commit errors in carrying out the measurements, because of micro-irregularities of their structure and geometry. Therefore, after the production of a CMM, a procedure called geometrical compensation is carried out: it consists in measuring such imperfections and transforming them into a Compensation Map to be downloaded into the CMM controller. In order to maintain a high-performance level, an accurate error model is necessary to appropriately compensate the data acquired by the machine. The availability of novel technologies also impacted the process of CMM compensation. Among them, the Laser Tracer (LT) enabled to improve the process, by reducing the overall time necessary for map estimation without negative effects on the uncertainty of the measurements. The main goal of the thesis is to study the feasibility of integrating the LT technology into a compensation process. To this purpose, use cases have been provided by the Grugliasco plant of Hexagon Metrology. The technology has been applied on different machine families, including a horizontal-arm. The outcome of this new approach has been compared with the actual method used in the plant, both online and offline through a Matlab simulator appropriately developed. Promising results have been found.