Indian Journal of Science and Technology

Abstract

This paper is about the mechanical properties and shape of the automobile piston in the engine. Currently downsizing of the engine is attractive field for the research which benefitted in the reduction of fuel consumption and emission pollutants from the engine. While on the other side various pressure boosters attached with the engine piston-cylinder to maintain the output power at the bar/more than the bar. These attachments cause to produce high stresses and displacement vectors in the piston-cylinder and the gas forces generated during the combustion cause to produce thermal stresses on the face of the piston which sometime may leads to the failure of piston material. To withstand all these problems the material must be strong enough. Al-Si alloy is the main alloy material to manufacturing the piston because of low co-efficient of thermal expansion, minimum weight, high hardness and strength and good wear resistance properties. In result; Shallow depth Combustion Chamber (SCC) is most suitable for low speed while Omega Combustion Chamber (OCC) is preferred for high speed, but both combustion chamber produce high amount of NOx. Maximum suitable percentage is of Si is up to 12% to 19%. While centrifugal casting is most right method to manufacture the piston and heat treatment at 540°C for 8 h and aging at 190°C for 8 h is correctly choice to achieve optimum mechanical properties by heat treatment. The ingredient material of the Al-Si alloy, the casting techniques and heat treatment techniques directly affects the mechanical properties of the piston in downsizing engine. A very careful observation is required during the manufacturing of automobile piston to achieve desired mechanical properties.
Keywords: Alloying Elements, Casting Techniques, Hypereutectic Al-Si Piston alloy, Mechanical Properties, Shape of the Piston