Since the cylinder liner should have very high strength, it is mostly made up of grey cast iron.
How to manufacture a cylinder liner?
By centrifugal casting. The grey iron is headted in the induction furnace and the molten metal is taken to the centrifugal machine.
A mold is rotated continuously about its axis at high speed as the molten metal is poured causing the metal to distribute itself evenly around the die.
Since the impurities are lighter than iron, they are forced to the bore surface, due to the centrifugal force and later, they are removed by the machining.