OR Define grease under which situation it is used as lubricant?

Semisolid lubricant is a solid to semi-fluid product of dispersion of a thickening agent in a liquid lubricant. The most widely used semisolids lubricants are greases and Vaseline.

The semi solid lubricants are used under working conditions:

• Low speed and high pressure and high temperature upto $80^\circ C$

• In places where the bearing has to be scaled against entry of dirty water, dust and grit.

• Machines where liquid lubricant cannot be maintained in position due to intermittent operations of machine parts such as shaft.

• Machines used in textile mills, paper and food product manufacturing etc., where spilling and spurting of lubricant is harmful to the product.