The manufacturing of hard and refractory materials such as ceramics, glass or carbide poses particular challenges on tools and machines. The Sauer Limited a company of the DMG Mori Corporation has developed ultrasonic tool holders working in a frequency range from 15 to 60 kHz. The ultrasonic vibrations are superimposing the tool movement in the tool axis especially for the application on special materials. This technique causes a structural weakening in the contact area and facilitates the machining. For these special materials, a force reduction, mainly in drilling into carbide with diamond tools, of up to 30 percent is possible. This made the authors try to expand the application range of this method. To achieve evaluable results, the authors decided to start working with existing processes. This also makes it easier to understand the mechanism of the positive influence of the ultrasonic assistance. It is difficult to compare a grinding process of hard and brittle materials to the drilling of steel as these two operations are different in many ways. In the first case of investigation, the authors use tools with geometrically undefined edges, where as in the second case, the edges are geometrically defined. To get valid results of the tests, it has then been decided to investigate drilling. This manufacturing method anticipates the best results. The main target of the investigation is to reduce the cutting force. It is measured with a force measurement platform underneath the workpiece. Concerning the direction of the ultrasonic assistance, the authors expect lower cutting forces, longer endurance of the tool, a reduction of the burr height and a better surface quality in the drilling process. To verify the frequencies and the amplitudes, an FFT-analysis is performed. This analysis shows the increase of the damping. This raise depends on the infeed rate of the tool and thus reduces the amplitude of the cutting force.
Experimental Analysis of Cutting Force Reduction During Ultrasonic Assisted Turning of Ti6Al4V
