Comparative study of the volumetric positioning accuracy of CNC machining centres using the latest laser measurement technology

Machine tool manufacturers are striving to achieve maximum accuracy of their products. Geometric accuracy together with high speed has become the most important parameter of all CNC machine tools. Traditionally only the axial positioning errors have been checked and compensated (if necessary). Nowadays it is not sufficient to control only this type of error. Straightness, squareness and angular errors have to be also taken into account. Furthermore in connection with the increasing capabilities of modern control systems more complex compensations can be performed resulting into an outstanding volumetric accuracy. Reported here are the results of geometric measurements done by means of the latest laser measurement technology. Recently a set of mid-sized CNC machining centers was tested in order to compare the significance of the above-mentioned types of geometric errors. All measurements were done according to the international standards ISO 230-2, ISO 230-6 and by the laser vector method. Finally the effect of a volumetric compensation based on the output of the laser vector method is discussed as a possible action in order to improve the machine tool accuracy.