Laser-assisted grinding of silicon nitride by picosecond laser

Silicon nitride (Si3N4) is a high demanded structural ceramic with exceptional mechanical, thermal and chemical properties. Poor surface integrity and limited material removal rate due to high tool wear and cutting forces are the main problems of grinding this material. A novel laser-assisted grinding process is developed to overcome the current technological constraints in the grinding of Si3N4. Ultra-short pulsed laser radiations are efficiently applied to create ablation, controlled thermal damages and enhance the material removal rate in the grinding process. Two different laser structures have been produced on gas-pressure-sintered Si3N4 with various laser scan speeds and laser line spans. The high performance of the developed process is shown by experimental results. A substantial reduction in tangential and normal grinding forces and a slightly improved surface roughness have been achieved. The analysis of the surface integrity has shown a damage-free ground surface via laser assistance, where the pattern type of structures had a significant influence on the process results.