The Effect of Composition of a Calcium Sulfonate Complex Grease
on the Key Parameters for Electric Motor Bearing Grease Solongo Wilson Wayne Mackwood Introduction Calcium Sulfonate Complex (CSC) grease continues to grow in popularity as a premium grease for both end users and manufacturers. The 2014 NLGI Annual Survey has indicated that it accounts for almost 2% of the world grease production [1]. It is ideally suited to applications where heat, water, and high loads are present [4]. Several papers have shown that it can be used in a wide range of applications, from wheel bearings, food processing, nuclear power generation, steel mills, to marine equipment, and even wind turbines [2-13].
With Calcium Sulfonate Complex grease becoming more popular in heavy industries, and finding increasing use throughout a plant, its consideration for use in EMB lubrication is a natural next step. This paper will present a first look at several aspects of formulating a high performance CSC grease for electric motor bearings. In particular it will examine the effect of base oil type, base oil viscosity, and thickener content on the performance properties of the grease.
Simply put, an electric motor can be defined as a Background machine that converts electrical energy into mechanical An evaluation of several electric motor bearing energy. Electric motors can make up more than half of manufacturers’ grease recommendations show that any plant’s rotating equipment. In mining, electricallythe most commonly suggested grease thickeners are driven draglines and shovels use electric motors for polyurea, lithium, and lithium complex [15]. There is powering all of the rotating equipment on board. These a distinct absence of calcium sulfonate complex grease motors can be lubricated by oil or grease, depending in these recommendations. This study sought to assess on the orientation or application. In the case of greasethe suitability of CSC grease in EMB applications, lubricated motors, the predominant grease of choice is despite concerns about relatively high thickener contents a polyurea-thickened grease, particularly for factorywhen compared to other greases. In fact, the focus of fill bearings [14]. Lithium Complex grease and even the study was the manufacture of a new low-thickener simple Lithium grease may be recommended and used. content product aimed at fulfilling the requirements Regardless of the type of thickener chosen, however, the of an EMB grease. Fig 1 below shows the evolution of primary functions of an EMB grease would be to reduce the calcium sulfonate grease technology from a simple friction, prevent wear, protect bearings against corrosion, thickener to processes with declining thickener contents. and act as a seal to prevent entry of contaminants. Manufacturers of CSC grease have the option to vary Therefore, key properties to consider when formulating thickener contents from below 20% to over 30% [16would include high temperature life, operation at high 18]. The process described in Patent 5,308,514 (Method speeds, wear protection, and corrosion resistance. C) results in thickener contents more in line with other Extreme pressure performance is not typically considered thickener types [18]. critical. A high percentage of electric motors operate at 3600 rpm, with a few operating at higher speeds of 5000 up to 20000 rpm. - 14 VOLUME 80, NUMBER 1
