Automotive sleeves are basically cylindrical parts that are fitted into an engine block for the purpose of either forming a cylinder or for repairing of damaged cylinder bores. The sleeves generally are much harder compared to engine blocks and so are ideal for housing the piston, since the hardness of the sleeves prevents the piston from wearing through the cylinder bore. These sleeves are commonly used in almost all diesel engines and also are an absolute necessity in engine blocks made from aluminum, since aluminum engine blocks are too soft for containing a piston.
Automotive sleeves are also called as automotive liners, with either of the two names being used in different parts of the world. In japan, these are called as automotive liners, while in other parts of the world like the united states or countries in Europe, these are generally called as automotive sleeves. The sleeves are available in a wide assortment of dimensions, finishing options etc. Furthermore, the sleeves can also be customized according to a specific requirement.
Prerequisites for Automotive Sleeves
An ideal automotive sleeve should have the following attributes.
It should be dimensionally accurate
The sleeve must be manufactured to exacting tolerance for proper fitting
It must be able to withstand high level of hoop stress
Should also withstand high thermal stress
An automotive sleeve should be resistant to corrosion and wear
The sleeve should also have optimal porosity
Construction of Automotive Sleeves
The construction of automotive sleeves is done either by centrifugal casting or sand casting process. Centrifugal casting process is used for making small sleeves, while sand casting is ideal for larger automotive sleeves. The inner surface of the sleeves is generally chrome plated to make it smooth, however, recent drawbacks have been found in this design such as this design does not allow the oil to spread out properly, thus affecting lubrication. To rectify the aforementioned drawback, the use of porous chrome honing is gradually being increasingly preferred by sleeve manufacturers.
As for materials used in construction, cast iron alloyed with small quantities of nickel , copper, chromium etc. is preferred. The alloying here is almost always of the order of 5 percent.
Installation of Automotive Sleeves
The automobile's cylinder first must be stripped of all removable parts such as studs, bolts, nuts etc.
After measuring the outside diameter of the sleeve, the cylinder is bored out accordingly.
The cylinder is then heated in a temperature of 400-450 degrees Celsius for an hour.
Afterwards, the sleeve automatically drops easily into the cylinder, with a needle nose type device used for ensuring optimal fit.
The cylinder is then put under a hydraulic press to keep the sleeve from rising while the cylinder cools.
After cooling, the automotive sleeve must be bored out and honed to ensure proper piston clearance.