Dry friction occurs in an un-lubricated journal bearing.
Grey cast iron
In Grey cast iron materials no cutting oil is used when drilling.
when cutting steel with hand hacksaw, cutting oil is used .
Carry away the heat produced in bearing
Prevent metal-to-metal contact and reduce friction
Prevent entry of foreign material i.e dust, dirt etc. in the bearing
Provide a cushion to a load and shocks
No change in viscosity due to variation in temperature
Reduces friction between machine parts
Takes up the surface pressure between sliding parts
Becomes thicker after prolonged use