Mechanical roughing of cylinder bores in light metal crankcases

The increasing demand on vehicles with reduced fuel consumption and emission is the reason why aluminum is frequently used as material for crankcases in the automotive industry. Eutectic aluminum alloys, however, have the disadvantage that they cannot be used for the cylinder bore surface due to their tribological qualities. A method to increase the wear resistance is to coat the surface by using a thermal spray process. In this case a coating material e.g. a steel wire is melted. The molten particles solidify at the boring surface so that a wear resistant coating of the cylinder bore is produced. In order to guarantee that the coating adheres to the aluminum, it is necessary to roughen the surface. This paper describes a method of roughing the surface of the cylinder bores of light metal crankcases by using a modified fine boring process.