rotating graphite disc electrode to draw up, or alternatively the sample cup will be picked up during rotation. Thus, an alternative protocol will be required to allow for elemental analysis of the grease, such as those listed in Figure 4-1. The intention of this study is to perform a repeatability study, in order to determine the correlation between the grease elemental analyses results obtained from the four RDE-AES protocols, across the most common categories of lubricant grease found in rolling element bearing applications with the comparison of data encompassing repeatability or variation, recovery and additional protocol criteria of concern as given in Section 4.4.1. These parameters will illustrate the potential advantages and limitations between the protocols investigated. The ultimate goal is for simultaneous multi-elemental analysis of grease through RDE-AES for condition monitoring that can permit the detection of elements likely to be encountered in typical applications, including wear metals, lubricant additives, thickeners and contaminants. In order to be conducted precisely, and because the composition of lubricant greases are so varied as shown in Chapter 2, the study encompassed four greases. The selection was based on the most common grease type by thickener classification, encompassing the two main classes of grease; soap and non-soap grease. The grease selection used in the study can be seen in Table 4-1. Table 4-1: Grease Selection for RDE-AES Appraisal
Lithium
G4
Bentonite Clay
Highly refined mineral oil
Mineral Oil
59
2
Soap
2
0/00
NonSoap
Mallueas
G3
Soap
Rockman
oil
Starplex
Complex
Renolit
Highly refined mineral
2
Product
Lithium- Calcium
Soap
OHG
oil
Grade
MP2
G2
Highly refined mineral
NGLI
EP 2
Lithium-Complex
Class
LX EP 2
G1
Base Oil
Name
Thickener
Red
ID