Visualization of grease fluidity in a ball bearing using neutron imaging technology

Sakai, Kazumi*; Ogata, Rui*; Kimura, Nobuharu*; Matsumoto, Yoshihiro*; Kurita, Keisuke  

Neutron imaging technique was applied to visualize grease fluidity in bearings which determines the bearing torque property. Two types of lithium (Li) greases with different thickeners were used in this study. The Li complex grease was superior in lowering bearing torque related to energy-saving performance. After bearing rotations, neutron radiography and computed tomography measurements of the greases distributed in the bearings were performed. Adhesion of the Li complex grease to bearing balls was quite limited, and most of the grease stayed on cage surfaces between the balls; adhesion of single Li soap grease to bearing balls was remarkable. The neutron radiography with bearing rotations was also conducted to capture the moment of the grease flow. The observation with bearing rotations revealed that single Li soap grease flows gradually not from the beginning of bearing rotations. Based on these results, the lubrication mechanisms will be proposed.