Face diagonal positioning and straightness error motions of machining centres according to ISO standards

According to ISO 230-6:2002, diagonal tests can be applied to evaluate the volumetric performance of a machine tool. In the mentioned standard, “positioning errors” of four body diagonals are measured separately and compared with each other. The same can be done for every pair of face diagonals in XY, YZ and ZX planes. The latest revision of ISO 230-1 in 2012 introduced the concept of “diagonal straightness tests” of the linear trajectories made by interpolation of two or three linear axes of a machine tool on its face and body diagonals respectively. In this research work, some positioning and straightness tests are conducted along linear trajectories at different angles (partial face diagonals) in the horizontal XY plane of a vertical machining centre with kinematic chain of [w X’ Y’ b Z (C) t]. To present the results, we introduce two components of face diagonal straightness, not yet covered in current ISO standards. These additions offer a more comprehensive analysis of the results and performance of the machine tool under test. The results of experiments are compared with the predicted results obtained by simulation computed based on the homogeneous transformation matrices (HTM) method in XY plane via error motions of the linear axes and their squareness error.