Measurement Uncertainty of Blade Surface by Coordinates Measuring Machines in Rotation and Parallel Sampling Modes

This paper aims to investigate the measurement uncertainty of blade surface by coordinates measuring machines (CMMs) in different sampling modes. Two different sampling methods for the blade surface, which are the parallel mode and the rotation mode, are studied to examine their measurement uncertainty. The fundamental principles and operational processes of the two modes are presented and discussed. The measurements were performed on a twisted-face blade, and data processing was also conducted to fit the cross-section profile both of the base surface and back surface separately. Then the measurement uncertainties of two sampling methods were evaluated on different parts of the blade surface in terms of the surface profile's curvature and twist rate. It is found that the measurement of blade surface by CMMs shows much uncertainty for both of the sampling modes because of the complexity of the blade surface. The back surface's measurement uncertainty is larger than that of the base surface. The measurement uncertainty of cross-section profiles on the top blade surface is larger than that of the bottom blade surface. In addition, the difference between the measurement uncertainties of two sampling methods is small, especially for the base blade surface. The research means that both sampling methods can be a practical application choice for the measurement of blade surface by CMMs.