Tool Path Modification Approaches to Enhance Machining Geometric Accuracy in 3-Axis and 5-Axis Machining

Abstract

Introduction Precision manufacture of components has become a necessity in the present day manufacturing sectors. The ever-increasing demands of humankind have forced researchers to come up with more improved innovations in technology; achieving higher levels of integration in microprocessors, and creating more versatile and precision multitasking systems being just a few of the major drivers in this area. All these, however, have one rudimentary requirement, namely, the need to use very high precision components. Hence, it can be very safely concluded that the success of each of these industries hinges on the ability to produce such components. Recently, as the tremendous demands for mechanical parts with high geometric and dimensional accuracy increase, an exigency to produce those parts with such accuracy is greatly comprehended by today’s manufacturing industries. To this end, CNC machine tools are the most important means of production for the manufacturing industries. CNC machine tools have been widely applied to a range of applications, for example, in the aerospace industries. With the recent advancement of the machine tools manufacturing technologies including high speed feed drives and high speed spindles, high speed end milling on the CNC machine tools has become constantly popular, and is being performed to manufacture the components with the required contour geometry and dimensional accuracy. However, the geometric accuracy of the machined surface is greatly affected by the numerous errors sources ranging from errors existing in the machine tool system itself to the errors due to the cutting process. Figure 1-1 shows the general error sources that influence the machining geometric accuracy [Kakino et al., 1993]. Broadly, machining geometric errors are caused by two major error sources: motion errors of the machine tool system and errors due to the machining process. The key factors among error sources in the machine tool system that cause deviation of tool tip position relative to workpiece, and hence machining geometric errors are positioning errors and volumetric errors. Here, positioning errors are defined as the linear errors of the positioning mechanism, whose directions are in parallel with the direction of axis movement required for desired positioning. On the other hand, volumetric errors are here defined as error components whose directions are perpendicular to the direction of axis movement.