with respect to receprocating engines,what causes the liner wear. and what is the role of honning.?

Answer 1

THe constant movement and friction of the piston rings against the walls of the cylinder(or Liner) causes wear over a period of time even with the lubrication of fluids. when you hone the cylinder it removes all scratches and imperfections in the cylinder and helps make it round again. After honing you may need to go to an oversized set of rings or piston.

Answer 2

I believe that deezone13 nailed it for you. I could add that in the 50's new cars had to be driven several hundred miles at low breakin speed to ensure long engine life. Later this was not necessary because the cylinder liners of new cars were honed much better. When you drill a hole in metal it may appear rough under great magnification and honing smoothes out the metal surface. When properly honed, the action of the piston and rings against the cylinder wall when well lubricated actually continues to hone the liner wall. If the liner becomes worn (perhaps from dirty oil or metal chips not removed by the oil filter) the liner may be re-bored and honed again and may require larger piston rings. Some experts still recommend a breakin period for new cars (avoiding top speeds) until oil (olifins?) chemically combine with the moving metal surfaces to help protect them.

Answer 3

honing not honning
honing is done to create pockets on the liner in order to hold the lube oil so as to provide better lubrication for the piston

otherwise all the oil will just slide down and the piston will fail