Grease performance requirements

Grease is used to prolong the life and increase the efficiency of mechanical devices by reducing friction and wear (ASTM D-4170, AST3VID-5707), and there are specific performance requirements (ASTM D-3527, ASTM D-4170, ASTM D-4289, ASTM D-4290, ASTM D-4693). Generally, a fluid lubricant (such as lubricating oil) is difficult to retain at the point of application and must be replenished frequently. On the other hand, a thickened fluid lubricant (grease) is easier to retain at the point of application, and lubrication intervals can be extended. 

Another impetus to expansion of this field was the advent of World War 11 and the development of the atomic bomb. The desired isotope of uranium, in the form of UF was prepared by a gaseous diffusion separation process of the mixed isotopes (see Fluorine). UF is extremely reactive and required contact with inert organic materials as process seals and greases. The wartime Manhattan Project successfully developed a family of stable materials for UF service. These early materials later evolved into the current fluorochemical and fluoropolymer materials industry. A detailed description of the fluorine research performed on the Manhattan Project has been pubUshed (2). 

Consistent performance in today s feed conversion-animal production industries requires consistent feedstuffs. In addition to providing products free of chick edema factors, pesticides, herbicides, polychlorinated biphenyls (PCBs), and other hazardous contaminants, the tallow and grease supplier is expected to deliver products with increasingly consistent fatty acid profiles. This requires appropriate... 

Work Scope Procedures clearly scope the work an individual is expected to perform. They ensure work is executed the way management or engineering requires. If management wants 12 shots of grease pumped into the bearing, allowing 15 sec to elapse between shots, this desire can be clearly documented in the procedures. 

Abstract Grease lubrication is a complex mixture of science and engineering, requires an interdisciplinary approach, and is applied to the majority of bearings worldwide. Grease can be more than a lubricant it is often expected to perform as a seal, corrosion inhibitor, shock absorber and a noise suppressant. It is a viscoelastic plastic solid, therefore, a liquid or solid, dependent upon the applied physical conditions of stress and/or temperature, with a yield value, ao- It has a coarse structure of filaments within a matrix. The suitability of flow properties of a grease for an application is best determined using a controlled stress rheometer for the frequency response of parameters such as yield, a, complex shear modulus, G phase angle, 5, and the complex viscosity, rj. ... 

Contaminants may be of three general types particulates, highly polar (ionic) residues, and nonpolar (grease-Uke) residues. In many production environments, all three types are present and several solvents and cleaning processes may be required to remove them. Both the choice of solvent or cleaning solution and the cleaning process are critical, and several theoretical principles may be followed in their selection. Ultimately, cleaning is more an art than a science, and the procedure chosen should be experimentally verified in each case. Qualitative and quantitative tests can be performed to determine the efficiency of a selected solvent and process. 

Industrial lubricants include metalworking lubricants, industrial greases, industrial lubricants, transformer oils, hydraulic oils, refrigeration oils, turbine oils, compressor oils, rock drill lubricants, paper machine oils, way lubricants, and railway journal box oils. The required additive package for each of these industrial oils is different depending on its specific application. Unlike lubricants used in automotive lubrication, industrial lubricants typically do not use metallic detergents and ashless dispersants as additives to keep metal surfaces clean and prevent insoluble materials from formation of deposits on metal surfaces [23]. However, in recent years the use of overbased detergents to supplement performance of the antiwear additive zinc dialkyl dithiophosphate has been reported [24]. 

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