A piston ring is an expandable split ring used to provide a seal between the piston an the cylinder wall. Piston rings are commonly made from cast iron. Cast iron retains the integrity of its original shape under heat, load, and other dynamic forces. The piston rings, which are also called as comparison rings are fit closely in the grooves provided in the piston. These rings are worn out before the wearing of the piston and cylinder wall. These rings form an effective seal and at the same time transmit heat from crown to the cylinder walls. Hence keep the temperature within the workable limit. There should be at least two piston rings in each piston of an internal combustion engine. For the higher capacity engines, there are four or even six piston rings have been used. The number of rings is depending upon the capacity and size of the I. C. Engine. In order to achieve the effective seal against lube oil and high-pressure gases leakage, a great pressure must be exerted, by each ring on the cylinder walls.
Piston assembly is a heart of the IC engine. The piston assembly is composed of five basic components which are piston, piston rings, gudgeon pin, connecting rod and bearings. The piston in general is casted out of aluminium alloys and has the responsibility of take all rigorous forces. The piston is connected to crank through connecting rod pivoting around the gudgeon pin. The piston rings are split rings assembled into the grooves on the outer diameter of the piston. The piston rings is a combination of three rings serving specific purpose in running engine. The top most groove ring is known as compression ring or pressure ring which provide sealing above the piston and prevents the gas leakage from the combustion side. The second or intermediate ring act as lubrication control ring and provides enough lubrication to the compression ring and prevent scuffing. The third ring is known as oil ring or oil control ring, these rings controls the amount of lubricating oil passing up or down the cylinder walls. Also, the piston rings act as a medium to transfer heat generated while combustion and provide overall support to the piston in the cylinder.
There are over 1.5 billion on road vehicles around the world which creates substantial aftermarket opportunities for the piston rings manufacturers. Also, over 110 million vehicle are produced annually among which over 70% are equipped with multi cylinder engines. The global automotive market is growth at a pace ranging between 3.5% - 4.5% annually. Growing automotive sales coupled with growth in population and affordability is anticipated to play a key role in the growth of global piston rings market. Also, piston rings are among the essential components which have the direct influence on the vehicle performance, engine power and efficiency, hence required frequent monitoring as they contribute to around 24% over all friction generated in the engine.