Crankshaft is also known as crank.It is the important part of an engine to convert the up and down motion of the pistons into horizontal rotation.It is usually made by cast iron or forged steel.The material of forged steel is usually used in high loading situations,such as diesel or turbocharged engines.Petrol passanges cars are either used cast iron or drilled into the crank shaft to distribute lubricant to the main and rod journals. It must endure the force from the connecting rods and converts it into rotary motion which is output through the crankshaft and drives the various parts of the engine to work.Shaft necks whirligig with high speed under high pressure,therefore, the crankshaft must be strong and rigid enough, and the surface of the journal should be wear-resistant, uniform and well balanced.