Cast versus forged engine pistons - Research Paper Example

Centrifugal casting has been used for the production of cylindrical parts since time immemorial. The two types of machines used to achieve these are broadly classified as horizontal and vertical types. The horizontal ones are named so because they usually rotate around a horizontal axis while the vertical ones rotate around a vertical one. The horizontal machines are typically used to make pistons and other castings that are simple in shape. The vertical machines are best suited for making castings that are not regular in shape (Soares, 22).

The importance of pistons can not be bargained. In a typical engine, pistons are used in order to convert the thermal energy into mechanical energy. Pistons are used to convey the gas forces through the linking rods to the crank shaft. They are also used in order to seal off the combustion part against the possible gas leaks in the crankcase. In addition to preventing leakages, they also help to avert any possible infiltration of oil that might emanate from the crankcase into the combustion part of the system.

Last but not least, pistons are used to release the heat absorbed as a result of the combustion thereby assisting in the function of the cooling oil. The pros and cons As we have observed, aluminium is a preferred material in pistons, whether one is using casting or forging. Aluminium has a high thermal conductivity which makes it a very ideal material for the job. The modern gasoline as well as diesel engines have created a need for the creation of pistons that are lighter in weight but at the same time that have a greater capacity of thermal load.

This has been made possible due to the novel designs through the use of innovative coating technologies. Pistons are usually exposed to very robust conditions. The mechanical load that the pistons have to handle comes from the very high pressure in the combustion part. The pressure typically goes up to 200 bars. Another source of mechanical load is the extreme force of inertia. This is as a result of heightened acceleration of reciprocating motion pistons (Soares, 27). Pistons can either be produced from cast or from forged aluminium alloys.

There are different types of alloys that are used in the casting or forging of pistons. The first type is the standard piston alloy. It is an eutectic Al-12% Si alloy. On average, it has at least one percent each of Cu, Mg and Ni. In order to meet the demands of the current modern engines, there have been special eutectic alloys developed in order to achieve better resistance to extreme conditions. The hypereutectic alloys typically have eighteen and twenty four percent of Si. They come with the advantage of lower thermal expansion but they have the disadvantage of lower strength.

Developers of pistons usually have their own customizations in order to fit the different unique requirements but they are generally based on these underlying principles. Most of the pistons on the market are developed using the gravity die casting technique. One important advantage of casting is that the optimized alloys in conjuction with the controlled environemtn of production make the development of the pistons that are low in weight possible (Soares, 23). Forged pistons however, win over their casted counterparts when it comes to withstanding higher pressure.

The forged