No abstract

In this paper, the wear performance of hybrid radial bearing (PEEK-PTFE and alumina ball) was investigated. For effective operation of equipment in clean energy facilities environment, the PEEK-PTFE hybrid bearings was developed. Radial PEEK-PTFE hybrid bearings were produced by machining and their rolling contact fatigue (RCF) behavior under non-lubricated condition was carried out. PEEK accumulation layer with PTFE and graphite appeared on the bearing's inner ring under 600-3000 rpm rotation speed. Due to the self-lubrication of PEEK layer, the wear loss of hybrid bearing cycles was lower than in the case of neat PEEK radial bearing. Moreover, It was found that the thin PEEK layer protected the raceway from the friction heat and wear.

The production of bearings is focusing on polymers, such as polyether ether ketone (PEEK), a tough semi-crystalline thermoplastic polymer with excellent mechanical properties and polytetrafluoroethylene (PTFE), a material with low friction coefficient. The purpose of this study was to establish the properties of hybrid PEEK races – PTFE retainer bearings. Rolling contact fatigue tests were performed in order to investigate the wear properties of such components and the relation between load and rotation speed. It is concluded that by using a PTFE retainer, no wear occurs under thrust load ranging from 200N to 800N at 300rpm.

Radial ball bearings made of metal, ceramics and plastics are commonly used as important components in various types of industrial machinery. Due to the latest markets demands for elements capable of withstanding e.g. corrosive environment, metallic bearings are being gradually replaced by components produced from high performance engineering plastic polymers. In order to investigate the failure mechanism of polymer bearings and further improve their performance in practical applications in an underwater environment, in this research crack propagation in Poly-ether-ether-ketone (PEEK) was studied by rolling contact fatigue (RCF) testing under water. Crack propagation in the inner ring raceway surface and subsurface areas of PEEK bearings after testing was observed by a laser confocal microscope. Cracks and flaking failure were found on the bearing raceway surface. From the RCF tests results, it was found that the detected cracks could be divided into three groups: Main Surface Cracks, Semi-circular Cracks and Main Subsurface Cracks. It is concluded that flaking occurs on the inner ring raceway due to the fusion of semi-circular cracks and a main subsurface crack.

Polyetheretherketone (PEEK) is a tough semi-crystalline thermoplastic polymer with excellent mechanical properties. While abilities of polyphenylenesulfide (PPS) are similar to PEEK, former material cost was lower than later. Polytetrafluoroethylene (PTFE) is well known because of its low friction coefficient and self lubrication ability. The objective of this study is to observe the friction coefficient of hybrid bearings, PTFE retainer sandwiched with PPS-races or PEEK-races. Rolling contact fatigue tests were performed and in situ friction forces wear measured. It is concluded that the PTFE retainer reduced friction coefficient.