What is Cylinder Liner? | What are the types of the Cylinder Liner?

The engine is one of the most important parts of the vehicle. It produces power to run the vehicle. The vehicle engine consists of different parts. The cylinder liner is a most important part of the engine. It is also known as a cylinder sleeve. It ensures the smooth running of the piston. This article mainly explains the various aspects of the cylinder liner.

What is a Cylinder Liner?

The cylinder liner is a sleeve placed on the engine block bore to create a cylindrical design. The engine piston moves back and forth in the cylinder liner. It is a vital part of the vehicle that makes up the smooth internal side of the engine.

cylinder liner

Cylinder liners are commonly used on engines with aluminum alloy engine blocks. This is because the aluminum alloy engine block without a liner has poor wear resistance and may warp at high temperatures. Therefore, linear is used for a better surface that can bear high temperatures and pressures.

The life cycle of the cylinder between its re-bores varies according to the following factors:

  • Corrosion
  • Abrasion

The abrasion is highly dependent on the atmospheric conditions and the efficiency of the oil and air filters. Dusty air is very dangerous because it increases cylinder wear.

The corrosive products produced after the combustion of the air-fuel mixture cause cylinder corrosion.

Acidic moisture on the cylinder wall also accelerates corrosion at low temperatures. The cylinder liners increase the service life of the engine cylinder.  

High-quality materials are used for the construction of the liners. You can easily remove and replace the liner.

The cylinder liner must have excellent wear resistance and the capability to hold oil to lubricate the surface between the piston ring and the wall.

Function of Cylinder Liner

The cylinder liner is one of the most important parts of the piston pump or engine. It is an area in which the piston moves. The main function of the cylinder liner is to reduce leakage and provide a smooth sliding surface and space for coolant heat transfer.

function of cylinder liner

The cylinder liner has a cylindrical shape. It is made from a special iron alloy comprising chromium, nickel, manganese, and silicon.

The cylinder liner has the following major functions:

1) Sliding Surface

One of the main functions of the cylinder liner is to provide a sliding surface for the motion of the piston. It acts as the internal wall of the cylinder. It traps the lubricant. The cylinder liner has the following major features:  

  1. Outstanding wear resistance
  2. Less wear on the cylinder liner itself
  3. Low lubricant consumption
  4. Less wear on the opposing piston ring

2) Assist in Transferring Heat

The wet liner transfers heat to the coolant to reduce the engine temperature up to the optimal operating temperature, and the dry liner transfers heat directly to the engine block.

3) Provide Excellent Sealing

The liner has a smooth surface. Therefore, when it makes contact with the piston ring, it provides excellent sealing and lessens the gas leak in compression and exhaust gases.

4) Withstands the Combustion

The cylinder liner has the ability to bear high temperatures and pressures during combustion, so the engine block is not heavily stressed.

5) Protect Wear and Tear

A liner serves as a wear and tear protector to prevent the cylinder block from damage.

Read More: Different types of Engines

Types of Cylinder Liners

The cylinder liner has the following types:

  1. Dry liner
  2. Wet liner
  3. Finned cylinder liner

1) Dry Liner

This type of cylinder liner has a shape like a barrel. It has a flange installed at the top. This flange holds the liner in a similar position to the engine block. These liners don’t have direct contact with the cooling water.

Dry Liner

The socket sits exactly in the cylinder. A precise contact between the socket and block is required for efficient cooling of the cylinder socket.  

In addition, the impact loading, piston thrust, and gas pressure during air-fuel mixture combustion are opposed through the full thickness of the cylinder and socket.

That’s why, the dry liner is thinner. The range of the dry liner wall thickness is from 1.5mm to 3mm and is mainly used to repair worn linings.

2) Wet Liner

In the wet liner, the liner makes contact with the cooling water or coolant. There is a flange on top of the liner that fits into the groove in the cylinder block.

Wet liner

The lower edge of the wet liner is sealed by using a packing ring or sealing ring to prevent cooled water from leaking into the crankcase.

When the wet liner faces the shear, gas pressure, and impact loads, the liner wall thickness increases. Therefore, the wet liner has a greater thickness than the wall thickness of the dry liner.

The wet liner has a wall thickness between 3mm and 6mm. The aluminum is used to coat the external side of the liner. This coating is compulsory to prevent rust.

Wet liners are more cooled than dry liners. It can be easily removed if worn or damaged.

3) Finned Cylinder Liners

The finned cylinder liner has a very similar working to the dry liner, but it has sockets around the outer surface to help with heat dissipation.

Heat and dirt resistant metals are usually utilized in the manufacture of finned liners. These types of liners are mainly designed for air-cooled engines. It is equipped with small fins that suck in the incoming air with great force to cool the cylinder efficiently.

Read More: Working and Function of Engine Cycline Block

Cylinder Liner Construction Material

Cylinder liners are mainly made from cast iron due to its unique characteristics. Cast iron contains graphite contents that serve as a natural lubricant, enhancing its suitability for this purpose.

A centrifugal casting is used for the manufacturing of cylinder liners. In this casting process, the raw material is sourced directly from the blast furnace.

However, the cylinder liner materials must have different characteristics to perform different jobs. Therefore, cast iron is often alloyed with other materials to create a composite material that can better fulfill the requirements of the cylinder liners.

The following are the most common materials alloyed with cast iron to manufacture cylinder liners:

1) Chromium

The incorporation of chromium into cast iron enhances the liner’s wear resistance and hardness. It also improves the corrosion resistance ability of the liner.

2) Silicon

Silicon plays a role in diminishing liner shrinkage and stimulating the overall structure.

3) Nickel

Nickle is used in a very small quantity. It is introduced to enhance the cast iron’s machinability and ensure consistent strength throughout the entirety of the casting.

4) Molybdenum

Molybdenum plays a vital role in increasing the liner strength and wear resistance, offering valuable resistance against excessive pressures and temperatures.

5) Vanadium

Vanadium is added to enhance the liner’s metallic structure. It also helps to reduce fragility and boost hardness.

6) Copper

Copper helps in improving the cast iron’s pearlite structure, reducing friction coefficients, and creating an optimal sliding surface. Additionally, it enhances the liner’s resistance to corrosion.

7) Phosphorus

Phosphorus improves the cast iron’s grain structure.

8) Titanium

Titanium is used because of its reaction with nitrogen, leading to the formation of Titanium nitride, which mitigates the presence of blow holes and minimizes the occurrence of compact graphite structures.

Difference between Dry Liner and Wet Liner

  1. The cylinder block with a dry liner is stronger than the wet liner.
  2. The wet liner wall has more thickness than the dry liner wall.
  3. Wet liners can be trimmed before installation, but dry liners must be trimmed after installation.
  4. The dry liners don’t make direct contact with the coolant but protect the piston from wear and contamination. However, the wet liners make direct contact with the coolant.
  5. Wet liners don’t need to be trimmed accurately on the outside, but dry siding must be trimmed accurately.
  6. The dry liners are installed directly against the block cooling jacket wall. The wet liners don’t need special tools for installation and replacement.
  7. Wet liners have a higher heat transfer rate than dry liners. 
  8. Wet cylinder liners require a leak-proof seal to prevent cooling water from entering the crankcase, but dry cylinder liners do not need a leak-proof seal.
  9. The wet liners make direct contact with the coolant and are therefore adequately cooled, while the dry liner is not in direct contact with the coolant. Therefore, the dry liner has a higher operating temperature than the operating temperature of the wet liner.
  10. The thickness of the wet liner is 3mm to 6mm, while the thickness of the dry liner is 1.5mm to 3mm.

Composition of Different Materials in the Cylinder Liner

Materials Chemical Composition in %
Cast iron2 to 4%
Silicon1.6 to 2.7%
Chromium0.006 to 0.4%
Titanium0.005 to 0.05%
Nickel0.005 to 0.5%
Vanadium0.02 to 0.54%

FAQ Section

What is the function of the cylinder liner?

The main function of the cylinder liner is to reduce leakage and provide a sliding surface for the piston ring.  The engine piston moves inside the liner.

What are the types of the cylinder liners?

The cylinder liners have the following major types:

  1. Dry liner
  2. Finned liner
  3. Wet liner

What is cylinder liner in ship?

The cylinder liner is a cylindrical component installed into the engine block to form a cylinder. It plays a big role to form the interior of the engine.

Read More
  1. Different types of Engines
  2. Types of Internal Combustion Engines
  3. Working and types of Crankshaft 
  4. Function of Engine Valves
  5. Purpose and working of Heat Sink

Leave a Comment