The actual contact surface of the friction clutch is the friction lining. Linings are subjected to severe rubbing during a machine run. There are many factors that decide the material for lining is viable or not. However, the lining material should have certain qualities.
It should have a relatively high and uniform coefficient of friction under all service conditions.
High resistance to wear.
It should withstand a high compressive load.
It should be chemically inert, oil and moisture have no effect on them.
High heat conductivity. It should rapidly dissipate the heat generated.
It should have excellent compatibility with cast iron facing.