Hybrid cutting of granite by use of ultrasonic assistance

Hybrid technologies offer an important approach to enhance existing limits of conventional cutting manufacturing processes. Superposition of the infeed with adapted ultrasonic vibrations enables reductions of machining forces. This results in diminished tool wear and longer tool life. Furthermore, an increase of removal rates can be achieved. Successful machining of recalcitrant metal-based materials by ultrasonic assisted systems creates a high potential to gain similar effects in machining of mineral-based materials. This will be studied in this article. The state of the art for the machining of stone uses geometrically undefined cutting edges. This paper focuses on the geometrically defined cutting of granite with additional ultrasonic assistance. Cutting tests at a test station with linear cutting motion are being performed. The ultrasonic frequency is maintained at 20 kHz. Different oscillation amplitudes are applied to influence process forces and the wear of the used carbide metal and polycrystalline diamond cutting segments (PCD). A method to observe the wear is developed by use of a stereomicroscope and a 3D measurement system. This will enable conclusions about the applicability of the geometry of the cutting segments and the process parameters. Due to the significant different wear rates of both cutting materials, the cutting force progression by using PCD tools shows completely different characteristics compared to the machining with carbide metal tools.