Precision parts made from a wide variety of brittle materials have broad applications in healthcare, biomedical, energy, photonics, and automotive industries. A big challenge with high speed machining of brittle materials is to achieve high surface quality. A major problem encountered in machining these materials is random crack propagation into the workpiece, resulting in surface/subsurface cracks and thus strength degradation of the machined parts. Existing techniques rely on polishing, a very slow and costly process, to achieve high surface quality. This award supports fundamental research to provide needed knowledge for the development of a novel machining process to overcome this main limitation. The new process will enable high efficiency machining of brittle materials without compromising part quality. The results from this research will generate economic and societal benefits for the U.S. This research involves several disciplines including manufacturing, laser and optics, fracture mechanics, and biomaterials. The multi-disciplinary nature will help enlist underrepresented groups to conduct research and thus positively impact engineering education.
The objectives of this research are twofold. First, the relationship between femtosecond laser parameters (e.g., pulse energy, spot size, number of pulses) and microcrack geometry (e.g., crack length, crack orientation, crack gap) will be established. This objective will be achieved by performing laser micromachining experiments to generate seed cracks inside the workpiece material. Knowledge gained from this research will be used to inject seed cracks into the cutting zone of a workpiece. Second, the relationship between process parameters (e.g., machining conditions, tool geometry, crack geometry) and part quality (e.g., surface/subsurface damage, surface roughness) will be determined. This objective will be accomplished by conducting machining experiments, assisted by numerical modeling, and assessing part quality using surface profilometery, optical microscopy, scanning electron microscopy, and three-dimensional optical profilometry. This basic research will advance the knowledge base in machining brittle materials and enable new process developments based on controlled crack propagation.
