Rings are the basic elements that provide sealing while vacuum, compression, explosion and sweeping processes occur between the crankcase and the combustion chamber. In addition, it undertakes the task of transferring the high temperature caused by combustion to the cylinder and cooling water. The peak ring remains at an average temperature of 315 °C and under the influence of the highest gas pressure and undertakes the highest sealing function, followed by the middle groove ring, which is subjected to lower pressures. Oil rings, on the other hand, ensure that the excess oil remaining on the surface is stripped to the oil pan and a thin lubrication layer remains on the surface. Thus, excessive oil entering and burning of oil in the combustion chamber is prevented.

The number of these rings installed on the piston can vary depending on the engine type, speed and power. The use of 3, 4 and 5-ring engines is common. 

The rings used can have different shape features. In addition, as well as the shape characteristics of the rings, the coating properties may differ. Coating properties of the rings are of high importance in terms of wear and heat transmission properties and therefore lifetime. Chrome, chrome ceramic, phosphate and molybdenum coatings are commonly used.

Piston rings can be produced from different materials to fulfill their duties. These materials are generalized as cast iron and steels. 

Although pistons made of cast iron were used since the 1900s, the use of steel rings has been ongoing since the 1980s. 

As specified, rings are obtained by processing either of cast iron material or steel plates manufactured in precise dimensions.

When steel materials are compared in terms of tensile stress and modulus of elasticity, they have superior structural properties than cast iron materials. In addition, the high fatigue strength and thermal resistance of steels are an important advantage in the field of use. Coating is important in increasing the wear resistance of steel rings and nitride, plasma, cks and chrome coatings are used for this purpose.

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