Functional Properties of Grease

Functional properties of grease:

Advantages of Grease:

(1) Functions as a sealant to minimize leakage and to keep out contaminants. Because of its consistency, grease acts as a sealant to prevent lubricant leakage and also to prevent entrance of corrosive contaminants and foreign materials. It also acts to keep deteriorated seals effective (whereas an oil would simply seep away).

(2) Easier to contain than oil. Oil lubrication can require an expensive system of circulating equipment and complex retention devices. In comparison, grease, by virtue of its rigidity, is easily confined with simplified, less costly retention devices.

(3) Holds solid lubricants in suspension. Finely ground solid lubricants, such as molybdenum disulfide (moly) and graphite, are mixed with grease in high temperature service (over 315C [599 F]) or in extreme high-pressure applications. Grease holds solids in suspension while solids will settle out of oils.

(4) Fluid level does not have to be controlled and monitored.

Notable disadvantages of grease:

(1) Poor cooling. Due to its consistency, grease cannot dissipate heat by convection like a circulating oil.

(2) Resistance to motion. Grease has more resistance to motion at start-up than oil, so it is not appropriate for low torque/high speed operation.

(3) More difficult to handle than oil for dispensing, draining, and refilling. Also, exact amounts of lubricant cannot be as easily metered.