Vertical machining center accuracy characterization using laser interferometer: Part 2. Angular errors

This paper presents the results of accuracy characterization of a vertical machining center (VMC) in the form of angular errors and temperature variation using a low powered He–Ne (Renishaw®) laser calibration system along with environmental controller unit. The machine investigated is Cincinnati Milacron Sabre 750 3-axes VMC with Acramatic 2100 CNC open architecture controller. During angular error measurements, pitch and yaw errors of the X-, Y- and Z-axes were obtained. The accuracy of the VMC is characterized in the form of geometric and thermal errors as a function of machine tool nominal axis position, temperature distribution and environmental effect (air temperature, air pressure and relative humidity). The measured temperatures in conjunction with the geometric models are used to predict machine tool geometric and thermal errors. Results show that axis drive motors are the major heat sources. X-, Y- and Z-axes pitch errors are all sinusoidal in nature with an approximate wavelength of 4 in. X-axis pitch and Y-axis yaw errors are highest angular errors of the VMC.