Grease types selection

Further refinement is desirable concerning the preparation of grease type samples. Otherwise, the state of the art" appears satisfactory. No improvements or modifications of the test apparatus are anticipated presently. Results of this test are used as a basis for selection of materials for use in missile LOX systems. 

Oils in Greases. Essentially the same type of oil is used in compounding a grease as would normally be selected for oil lubrication. Petroleum oils are used in about 99% of the grease produced and commonly are in the SAE 20—30 viscosity range with about 100 130 mm /s viscosity at 40°C. Such oils provide low volatiHty for long life at elevated temperatures (50) together with low torque down to subzero temperatures. 

Once the lubricant type has been selected (base oil, viscosity, and additives), a decision must be made regarding the use of either oil or grease. Here, several more factors come into play. Questions that must be considered include ... 

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. 

Table 19.4 Composition of selected four types of carbon nanotube composites (greases)...

Frequently a situation is encountered where two or more variables must not be allowed to pass specified limits for reasons of economy, efficiency, or safety. If the number of controlled variables exceeds the number of manipulated variables, whichever ones are in most need must logically be selected for control. (This is the case of the squeaky wheel getting the grease.) Automatic selector units are available for this type of service. They are employed in four basic areas of application ... 

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