Hybrid machining represents a possibility for technological progress in production. As a part of hybrid machining processes, ultrasonic-assisted machining is often used to manufacture materials that are difficult to machine since process forces can be significantly reduced and the material removal rate (MRR) can be increased. This paper describes an approach for a model for ultrasonic-assisted drilling with undefined cutting edges. The ultrasonic vibration can theoretically be applied in axial, tangential or radial direction or it can be superimposed. An axial excitation, parallel to the feed direction, is selected in the presented model. Since the drilling is superimposed with a high-frequency vibration, the trajectories of the grains are modified. Therefore, an analytical-kinematic model is established, which is characterised by a periodical contact loss of tool and workpiece. Due to the modified kinematics, process-specific parameters, such as impact velocity or the ratio between vibration and cutting speed, are important, in addition to conventional cutting parameters. Such process parameters are useful to describe dominant material removal mechanisms in ultrasonic-assisted machining. Moreover, two models on tool topography are presented in this paper. Based on an analytical approach, the material removal rate, established by adding up the individual grain removals, is calculated. The quality of the developed models is validated by the standard calculation of the material removal rate by feed rate and tool cross section. The results show, that it must be taken into account that the grains do not hit an even surface. The grain distribution is also an important aspect.

Hybrid machining processes represent a potential approach to meeting the constantly increasing demands on cutting. In ultrasonic-assisted cutting, as a part of hybrid machining, the machining process is superimposed with a high-frequency vibration of small amplitude. This paper presents investigations on the drilling of stone materials, i.e. different granites and marble, in which this process is applied. It could be observed that the resultant forces and torques were reduced, which had already been discovered in investigations of various other materials. The influence of different parameters on the force reduction is shown, which is basically similar to the theoretical reduction of friction by ultrasound for small speed ratios δ, but is considerably increased. This increase must be due to other effects. Besides the force reduction, a reduction of cratering at the drill exit can be observed. Based on the present results, definite conclusions on tool wear cannot be drawn yet.

Ultrasonic assisted milling techniques utilize ultrasonic transducer as vibration source with advantages of low feed force and good surface finish quality. In this paper a project of ultrasonic assisted milling on stones and torsional transducer designed therefore are introduced. With the help of transfer matrix method, a parametric model is investigated and relations among geometrical parameters and final performance of transducer are simulated and discussed. Ansys is employed to fulfill fine improvement of model. Results of those two models are shown to match well.