Methods for controlling friction between heterogeneous contact surfaces

A method of conditioning a first, heterogeneous contact surface for operational engagement with a second contact surface, the method comprising:

• performing a smoothing operation on part or all of the first contact surface whilst subjecting said part or all of the first contact surface respectively to a contact pre-stress acting directly on the part or all of the first contact surface on which the smoothing operation is being performed, the contact pre-stress corresponding to a nominal operational contact stress between the first and second contact surfaces.