An Experimental study on grease fluidity in a ball bearing using neutron imaging technology

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

Rolling element bearings with grease lubrication are widely used for axis rotations in motors. Unlike liquid lubricants, the fluidity of semisolid greases in bearings plays an important role in bearing performances. The fluidity is often described as channeling and churning states. The states are well known, however, cannot be seen from outside bearings. Therefore, visualizations of greases in bearings are beneficial to understand the grease fluidity, however, methods for non-destructive observations of the inside of bearings are limited. The neutron imaging technology was applied for non-destructive observation of the grease fluidity inside a ball bearing in this study. The technology is based on a characteristic that neutron passes through heavy elements and interacts to light elements. In other words, neutron can identify lubricants with light elements inside the bearing with heavy elements.