Investigation of the cutting mechanisms during ultrasonic assisted machining of fibre reinforced non-oxide ceramics with geometrically defined cutting edge (CMCs)

• Applicant: Professor Dr.-Ing. Thomas Bergs
• Subject Area: Metal-Cutting and Abrasive Manufacturing Engineering
• Term: from 2021 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 457160135

The aim of the research project is to develop an explanatory model for the predominant cutting mechanisms in the ultrasonic-assisted machining of fibre-reinforced non-oxide ceramics. Due to ever stricter environmental regulations and strongly increasing intra-industry competition, the current development program of engine manufacturers focuses primarily on the demand for increased efficiency. One solution is ceramic composite materials that increase the maximum permissible material temperature and thus increase the engine efficiency. At present, there is no basic knowledge about the influence of tool vibration oriented in the cutting direction on the milling process of ceramic composites. In order to be able to determine the influence of a vibration oriented in the cutting direction on important process parameters under milling conditions, the simplification of the real milling operation to an orthogonal cut is used. Due to the good accessibility to the machining zone, the influence of vibration on the machining process can be investigated simply and fundamentally by varying cutting, vibration and tool sizes. The simplified conditions of orthogonal cutting in combination with the good accessibility to the cutting zone allow fundamental investigations regarding the influence of ultrasonic vibration. By using different cutting conditions (cutting speed, cutting depth, fiber orientation) and different tool geometries, the influence of tool vibration (vibration amplitude and vibration frequency) on important process parameters is investigated.At the beginning of the project, the characterization of the ultrasonic system and the used workpiece material is carried out. In the further course, an analytical modelling of the tool kinematics resulting from the vibration superposition takes place. This is implemented for the simple linear orthogonal section, followed by the derivation of characteristic process parameters, which are used to explain the chip formation as well as the predominant cutting mechanisms and the resulting surface quality within the framework of the modelling. In the following work package the tool geometry as well as the cutting and vibration parameters are examined for the machining behaviour and the resulting component quality. Based on the previous work packages, a qualitative description model for chip formation is developed. Based on all the knowledge gained and the given material properties, a heuristic model is finally drawn up, which explains the existing machining mechanisms fundamentally.

• DFG Programme: Research Grants