Bore Cylindricity in Finish Cylinder Boring

Abstract

Finish boring is a machining process to achieve the cylinder bore dimensional and geometrical accuracy. The bore cylindricity error sources, including the workpiece thermal expansion and deformation due to cutting and clamping forces, and spindle radial error motion, in finish boring were identified using combined experimental and finite element method (FEM) analysis. Experiments were conducted to measure the workpiece temperature, cutting and clamping forces, spindle error, and bore shape. FEM analysis of the workpiece temperature, thermal expansion, and deformation due to cutting and clamping forces was performed. The coordinate measurement machine (CMM) measurements of the bore after finish boring showed the 5.6 μm cylindricity and a broad spectrum from the second to tenth harmonics. The FEM revealed the effects of workpiece thermal expansion (1.7 μm cylindricity), deformation due to cutting force (0.8 μm cylindricity), and clamping force (1.9 μm cylindricity) on the finished bore and the dominance by the first to third harmonics using the three-jaw fixture. The spindle synchronous radial error motion (3.2 μm cylindricity) was dominated by the fourth and higher order harmonics and matched well with the high (above the fourth) harmonics in CMM measurements (2.9 μm cylindricity). The spindle error was the dominant error source for bore cylindricity in this finish boring study, contributing to about half of the total cylindricity error.