Experimental evaluation of tribo-performances of bump foil journal bearing with different materials of foil

Abstract In this paper, the bump foil journal bearing (FJB) is developed with five different foil materials: Inconel X750 (IN-X750), Stainless steel 316 (SS316), Beryllium copper (BC), Spring steel EN42J (SP EN42J) and Phosphor bronze (PB). A complete fabrication process is described in detail, along with the design of fixtures, to develop the bump FJB. This fabrication process includes various machining operations such as milling, rolling, cutting, threading, forming etc. The forming load versus deflection curve is obtained for all the foil materials with the metal forming operation. After fabricating it, the load-deflection test is performed to evaluate the structural characteristics (stiffness, energy dissipation and damping coefficient) of these developed bump FJB. Further, the tribological characteristics of bump FJB such as wear rate and surface roughness are evaluated by the experimental study. Moreover, the interface temperature of bump FJB is also captured by using the thermal imager. This study shows that the metal forming operation is the most challenging step among all the fabrication steps of bump FJB Among all the foil materials, the minimum wear rate and maximum surface roughness of bump FJB are observed for the IN-X750. The maximum spring-back effect in bump FJB is found for the Spring steel EN42J. These results demonstrate that the maximum energy dissipation and stiffness of bump FJB are observed for the Phosphor bronze and Inconel-X750 respectively. In addition, the damping coeffcient of bump FJB is evaluated.