Evaluation of the measurement uncertainty of the R-Test system enabling the measurement of the rotary axes position of five-axis CNC machine tools

The paper presents the results of the measurement uncertainty of the position of the rotary axes of five-axis CNC milling machines using the R-Test calibration system. The use of the modern system was the basis for obtaining experimental data, enabling the assessment of the uncertainty budget of the measurement system. The estimation was made based on the statistical analysis of the obtained measurements of the position of the rotary axes of CNC machine tools. Each value of the position of the rotary axes and the average value of the deviation of the reference ball center point were determined based on measurements performed in two directions, using 4 measuring radii, 4 feed rates and the full range of table rotation of both machine tools. Assuming the value of the expansion factor at the level of k = 2, the value of the expanded uncertainty U was determined. The standard uncertainties were in the range of 0.0019-0.0035. The standard uncertainty of the system according to the manufacturer’s documentation is 0.004.