G5등급 질화규소 세라믹 볼 베어링의 표면가공에 적합한ELID연삭 숫돌의 입도 선정

Abstract

Ceramic ball bearings are mainly used in high-speed, high-temperature, and corrosive environments owing to theirlow density, high rigidity, excellent heat resistance, and abrasion resistance. The surface roughness required for G5class ball bearings is 0.014 μm Ra or lower. Electrolytic In-Process Dressing (ELID) grinding has shown excellentperformance in achieving precise shape tolerances and nanoscale surfaces. This study aimed to determine whetherELID grinding can achieve the required surface roughness for ceramic materials used in ball bearings. Ceramicspecimens were prepared through high-temperature and high-pressure sintering at 1700 °C for 2 h using acomposition of Y2O3 and MgO in Si3N4. Experiments were performed using cast-iron bonded diamond wheels withmesh numbers #325, #1200, and #2000. The surface roughness values of the specimens processed with wheels #325,#1200, and #2000 were 0.166, 0.025, and 0.003 μm, respectively. The surface ground with the #2000 wheel satisfiedthe required surface roughness criterion of 0.014 μm Ra or lower in G5 class ball bearings