What is Liner Wear?
Cylinder liner requires adequate lubrication to reduce piston ring friction and wear.The oil film not only acts as a gas seal between the liner and piston rings, but also as a corrosion inhibitor.
If the cylinder lubrication is low the oil forced into the piston ring grooves reduces ultimately it causes the liner wear .And also due to acidic corrosion the wear takes place.
The rate of cylinder sleeve wear varies over the life of liner. It is high during the initial Running-in period after which it should reduce to an almost constant rate for most of the useful life of liner. Finally the wear rate progressively increases as the wear becomes excessive.
RUNNING-IN PERIOD :
It is nothing but the time period where running of engine is by using the newly fitted piston rings and liner after the replacement / renewal done in engine overhaul or running a new engine.
so new piston rings and liner may take certain period to form a perfect gas seal .Until this time the engine is run on low load & less speed to maintain a perfect Micro-seizure taking place this is called as RUNNING-IN PERIOD.
MAXIMUM wear of liner before renewal after the overhaul is usually (0.6-0.8)% of the original bore diameter .
For TWO-STROKE engines normal wear rate is about (0.0250 to 0.050)/1000 running hours.
For FOUR-STROKE engines normal wear rate is about (0.0125 to 0.025)/1000 running hours.