Material used in engine block casting
In order to meet the above functional requirements the material used for manufacturing the product should contain many properties. They are, the material should contain high strength, modulus of elasticity, wear resistance, ability to withstand vibrations, and corrosion resistance. high strength is mostly concerned in diesel engines because of their high compression ratios compared with petrol engines. In diesel engine its compression ratios are normally 17:1 or greater, but in petrol engine it is nearly 10:1. The material also should have low density to reduce its weight but with higher strength. It should also have a low thermal expansion under high operating temperatures and also a good thermal conductivity to give out the heat in minimum time. When it come to the manufacturing process the material should have good machinability and castability to reduce the time and cost consumed. As if the material is too hard the time and cost for manufacturing increases. When the engine is in running conditions it generates a higher vibration due to the motions in the internal parts like crank shaft and pistons, therefore the material has to be able to absorb the vibration energy with out fracturing.
The Term Paper on Steam Engine High Pressure
The steam engine is a machine used for converting heat energy into mechanical energy, using steam as the conversion medium. When water is boiled into steam its volume increases about 1, 600 times, producing a force that can be used to move a piston back and forth in a cylinder. The piston is attached to a crankshaft that converts the piston's back-and-forth motion into rotary motion for driving ...
Based on the above features the most widely used material are cast iron and aluminum alloys to manufacture the cylinder block. Cast iron alloys are used because they contain good mechanical properties, low cost, and availability compared with other metals. But certain aluminum alloys contain most of the characteristics of cast iron but with low weight. And also aluminum alloy casted engine block gives a good surface finish and high macinability compared with cast iron alloys. As the technology increases the engineers has found new materials such as graphite cast iron which is lighter and stronger than the grey cast iron mentioned above.
Grey cast iron alloys
Grey cast iron is the first and most material used for manufacturing of engine blocks. Though the aluminum alloy also contain many similarities with low weight, it is still used in the manufacturing of diesel engine blocks
because their internal stresses are higher. Grey cast iron contains 2.5 – 4 % of carbon, 1 -3 % of silicon, 0.2 – 1% manganese, 0.02 – 0.25 % of sulfur, and 0.02 – 1 % of phosphorus. It has a excellent damping absorption, good wear and thermal resistance, and it is easily machinable and less cost due to its availability.
Aluminum alloys
Aluminum alloys main feature for its popularity is its low weight, this reduce the weight of the engine as well as in the vehicle. But the main disadvantage is their cost compared with grey cast iron. Aluminum alloy has a good machinability properties compared with grey cast iron. There are two aluminum alloys that are mainly used in manufacturing of engine blocks, they are 319 and A356.
319 aluminum alloy contains 85.8 – 91.5 % of aluminum, 5.5 – 6.5 % of silicon, 3 – 4 % of copper, 0.35% of nickel, 0.25% of titanium, 0.5% of manganese, 1% of iron, 0.1% of magnesium, and 1% of zinc. This alloy has good casting features, corrosion resistance, and good thermal conductivity. Under the heat treatment of T5 process, it generates high strength and rigidity for the engine block.
A356 aluminum alloy contains 91.1 – 93.3 % of aluminum, 6.5 – 7.5 % of silicon, 0.25 – 0.45 % of magnesium, 0.2% of copper, 0.2% of titanium, 0.2% of iron, and 0.1% of zinc. Although the mechanical properties are similar to 319, when it is under the heat treatment process T6 it gains higher strength than 319. But it has lower modulus of elasticity (72.4 GPa) than 319 with modulus of elasticity of 74 GPa.
The Essay on Good Night and Good Luck
Good Night and Good Luck is a movie that tells the story of McCarthyism and the media campaign against it. Edward R. Murrow is described as the protagonist fighting against the evils of this man and his campaign. The greater message of the movie is the use of media. The ethical question posed is, what place does television have in society? At its conception, there was a debate. Was television ...
Compacted graphite cast iron
Compacted graphite cast iron has a higher tensile strength and modulus of elasticity compared with grey cast iron. It is due to the compact graphite found on the microstructure of CGI. Similar to grey cast iron it has a good damping absorption and thermal conduction, but its low machinability has
limited its wide usage.
