Why IC Engines are made of cast iron"?

Answer 1

You shoild specify about which part you are talking. There are different parts in an IC Engine. Some of them are: Crank, Connecting Rod, Gudgeon pin, Flywheel, Combustion Chamber or Cylinder Block, Valves, Piston rod, stuffing box, Cross-head assembly, Spark plug and Carburetter (in SI), Fuel pumps, Injection system, Engine Body, etc. Different parts are made of different materials, not all parts are made of CI. Also there are different manufacturing processes for different parts e.g. crank is produced by drop forging, cylinder block by casting, etc. Be more specific with your question to get better answers in future.

However, you may note that while machining CI no lubricant is required as the Graphite flakes act as solid lubricant. Also, CI is easier to cast than Steel.

Answer 2

It is easier to pour molten metal into a cast to make an engine block than to start with a large block of steel and machine it from scratch. It is said that the best way to sculpt a huge elephant is to start with a very large piece of marble and remove everything that does not look like an elephant. This may work well for one-of-a-kind objects but in mass production the engine block casting already looks like an engine block and merely needs machining where perfectly flat surfaces are required.

Answer 3

As psbhoumik says, only some parts are made of C.I
Cylinder liners and piston rings are made of C.I as graphite flakes in the cast iron act as a lubricant and prevents the seizing of the liner and piston. It is difficult to generate a thick film of lubricating oil in the liner due to high temperature existing inside.
Again, it is easier to cast complex structure with C.I than with steel. So the cylinder block and sometimes the crank-case too is made of cast iron.

Answer 4

1) it has great corrosion resistance than pure iron or steel.you can why we can go for BRASS, but it costlier than the cast iron.
2) It has a melting point in the range of 1420–1470 K. which is good to withstand temperature build in the engine.
3)Available in a wide range of mechanical/physical properties, i.e. tensile strength from 20 KSI to over 200 KSI, hardness from 120 to about 300 Brinell in standard grades and up to about 600 Brinell in special abrasion resistant grades
4)Good strength to weight ratio
5)Typically lower cost than competing materials and relatively low cost per unit of strength than other materials
6)Lower density and higher thermal conductivity than steels at comparable tensile strength levels
7)Excellent machinability, allowing for high speeds and feeds and reduced (minimal) energy due to the presence of free graphite
8)Many iron castings can be used without heat treatment (as-cast) but, when needed, can be heat treated to enhance overall properties or localized properties such as surface hardness
9)Excellent damping capacity, especially in Gray Irons
10)Chemical analysis can be modified to provide improved special properties such as corrosion resistance, oxidation resistance, wear or abrasion resistance, etc.
11)Rapid transition from design to finished product
12)Flexibility in design and ability to optimize appearance for sales appeal
13) Possibility of casting intricate shapes as well as very thin to very thick section sizes
14) Reduced tendency toward residual stresses and warpage than some competitive materials

Answer 5

Impossible to say except I would expect the majority to be of cast iron.