This academic-industry project is aimed at transferring laser-assisted machining (LAM) of structural ceramics from a laboratory science to commercial practice on the shop floor. During LAM, the ceramic workpiece is spot heated by precisely controlled lasers and then cut with a conventional single point cutting tool. With locally lowered ceramic strength at elevated temperatures, LAM can achieve higher material removal rates, reduced tool wear, and equivalent surface quality, compared to slow and costly diamond grinding. The LAM project team developed a unique multiple laser beam system and explored its capability for machining high strength silicon nitride in a production environment. LAM trials looked at both OD turning of 1" diameter silicon nitride rods with a CBN tool, optimizing LAM processing conditions for material removal rates, surface condition, and tool life. LAM machined rods were characterized for dimensional tolerances, surface roughness, and flexure strength to determine if LAM processing can produce strengths comparable to diamond grinding. The results presented show that the LAM machined samples show some improvement over the as received samples. This preliminary work also shows a correlation between the mean flexure strength and mean R_a, which is that strength increases as R_a decreases. Additional work will test this relationship.
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