Fiber laser assisted machining of silicon nitride

Laser Assisted Machining (LAM) of ceramics is an important area of manufacturing to improve the material removal rate and provide more geometric features that can be economically added to fully dense blanks over conventional course, intermediate, and fine diamond grinding. The challenges associated with the machinability of these advanced ceramic materials, specifically silicon nitride (Si₃N₄), has lead to laboratory demonstrations with LAM with traditional lasers such as CO₂ and ND:YAG. The advent of high power fiber diode lasers, offers a robust system that is suitable for industrial manufacturing environments. Bulk machining of Si₃N₄ requires the quantification of machining and laser settings that include but are not limited to the management of three dimensional temperature distributions due to surface energy absorption. With this understanding of thermal management, optimal conditions can then be tailored to specific ceramic systems. This work focuses on softening the glassy grain boundary phase of Si₃N₄ to produce a machineable surface without excessive tool wear or damage to the ceramic. This paper discusses improvements to the surface roughness and improved cutting techniques implemented in an industrial setting with the goal of economically machining other advance ceramics for the Energy and Transportation sectors among others.