Grease types application

When the type most suitable for a particular application has been chosen, the question of consistency must be considered. The general tendency over the last two decades has been towards softer grease than formerly used. Two factors have probably contributed to this trend the growth of automatic grease dispensing and the use of more viscous oils in grease making. 

Hence, the hot-dip compounds, or greases smeared cold, are better for assemblies with non-metallic parts masked if necessary. Solvent-containing protectives therefore find greater application in the protection of simple parts or components. The available means of application, the nature of any additional packaging and the economics and scale of the protective treatment are further factors that influence the choice of type of temporary corrosion preventive. 

The smearing types of material are usually lubricating grease compositions, i.e. blends of soaps and lubricating oil, biit may be mixtures containing petrolatum, oil, lanolin or fatty material. They are softer than the hot-dip materials to pOrmit cold application by smearing. 

Thiadiazole derivatives have been found to be useful as additives for lubricating greases and as vulcanization agents <1996CHEC-II(4)307>. No new applications of this type have been reported since the publication of CHEC-11(1996). 

The control of dynamic effects at impact rates up to 1 m/s (in some instances somewhat higher) frequently makes use of mechanical damping in the load transmission by placing a soft pad (elastomer or grease) between the striker tup and the specimen [3,5], Above about 1 m/s inertia effects overshadow the true mechanical response of the specimen. Due to such dynamic effects, the applicability of FBA is limited to loading rates up to about 1 to 2 m/s for bending type fracture specimens. 

By matching base oil type, viscosity, VI, additives, and thickener type (for grease) to the lubrication objectives, the optimum composite performance can result. The primary functions of a lubricant in typical machinery applications include the following ... 

This statement is also applicable to the causes of the most frequent manifestation of damage, namely stains. Statistical analysis of 258 cases of damage by stains resulted in 29 types of cause, each represented in more than seven cases. The most common types of cause gave frequencies in the range from 7-8%. These are, for example, stains caused by mechanical and chemical influences, dyestuffs, grease or oU, silicone and dead or immature cotton. 

Methods of analysis (ASTM D-128, IP 37) are available for the measurement of excessive acidity derived from oxidation. These methods cover conventional grease that consists essentially of petroleum oil and soap. Thus these test methods are applicable to many types but not all grease. The constituents covered by the test series are soap, unsaponifiable matter (base oil), water, free alkalinity, free fatty acid, fat, glycerin, and insoluble. A supplementary test method is also provided and is intended for application to grease that contains thickeners that are essentially insoluble in n-hexane and to grease that cannot be analyzed by conventional methods because of the presence of such constituents as nonpetroleum fluids or nonsoap-type thickeners, or both. These methods may not be applicable to grease analysis when lead, zinc, or aluminum soaps are present or in the presence of some additives such as sodium nitrite. 

Nevertheless, calcium greases of this type are still in use today for less demanding applications and their manufacture is very similar to the processes used over 100 years ago. Calcium soap is produced with a small residual water content which acts as a stabiliser for the soap matrix and thus provides the required structure of the thickener. In some operating conditions, when the temperature is constantly above 50°C, water evaporation may result in the complete breakdown of consistency in the grease and it will revert to a fluid state. 

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