Origin of the lateral return error in a five-axis ultraprecision machine tool and its influence on ball-end milling surface roughness

Precision ball-end milling is widely used in the manufacture of complex microstructures. The purpose of this paper is to explore the origin of the lateral return error in an ultraprecision five-axis machine tool and its influence on a precision ball-end milling surface. First, the origin of the lateral return error of the linear axis is analyzed. Theoretical analysis and experimental results show that the root of the lateral return error is the gap variation between the slider and the guide, which is decided by the eccentric force moment acting on the hydrostatic guideway. The eccentric force moment relies on the external force and motor eccentricity. In general, the larger the eccentric force moment, the more the gap variation, and resultantly the greater the lateral return error. In addition, the lateral return error is inversely proportional to the oil supply pressure. Because the cutting forces are small enough, the cutting parameters, such as feed speed, cutting depth and cutting stepover, have little effect on the error. Secondly, the lateral return error has an important impact on the yield surface roughness, which will significantly increase the surface roughness and reduce the surface quality. Finally, the lateral return error of the hydrostatic guideway can be suppressed by compensating the machining program. The experimental results show that the surface quality of the compensated surface is significantly improved.