AS9120B, ISO 9001:2015, AND FAA AC 0056B ACCREDITED

Cylinder Liners and Their Types

Cylinder liners are a common feature within engine blocks, and they are a sort of sleeve that lines the internal walls of a cylinder to safeguard metallic surfaces from wear and tear. As motors operate, pistons will pivot within a cylinder with rapid speed, resulting in a high pressure and temperature environment being formed. With a cast iron cylinder and an optimal liner, the service life of the assembly can be safeguarded from such stressors. In this blog, we will discuss cylinder liners in more detail, allowing you to have a better understanding of their functionality and types.

Cylinder liners will always be a centralized element within a reciprocating engine or pump where the piston is situated. Unlike soft liners that may be used in other applications, the liners of cylinders are constructed from special alloy iron consisting of manganese, nickel, chromium, and silicon that has been centrifugally casted. The innermost wall of the liner will need to accommodate piston rings, so it is designed to be a sliding surface with retained lubrication. Generally, the sliding surface will need to have high anti-galling properties, low wear for the liner and piston ring, as well as low lubricant consumption. As heat is also transmitted to coolants through the liner during combustion, it will need to have ample thermal conductivity. Lastly, liners are also designed to provide compression gas sealing so that exhaust does not escape during combustion.

Across vehicle types, cylinder liners can be categorized as dry, wet, or finned variations. With a dry liner, a barrel shaped assembly will be made with a flange on top, that of which serves to maintain the position of the cylinder block. As the outer surface of the liner always bears against the casting of the cylinder block, it must be accurately machined with a thickness ranging between 1.5 mm and 3 mm. With wet liners, a complete cylinder barrel is created with a flange that can be rested within the groove of the cylinder block. The reason for why these liners are known as wet liners is a result of their direct contact with cooling water. As the final type, finned cylinder liners are made from metals that are heat and impurity resistant, and they feature fins for air cooling. While being unique with the presence of fins, finned cylinder liners are fairly comparable to dry liners.

When deciding between each option, there are a few things that you can consider. For example, if your engine is air cooled, the finned cylinder liner is the best option due to its accommodating design. Meanwhile, the wet liner is known for its ability to reduce piston engine temperatures with ample efficiency with its direct contact with cooling water. By considering your application, requirements, restrictions, and other such factors, you can better make a purchasing decision.

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