Car crankshafts - are they forged or cnc cut?

Keep hearing one and another - have to decide for a customer(dont worry, its for a hobby project and a miniature motor of 0.5 CC.).

Does forging add that much more stiffness?

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Most modern, high-production automotive crankshafts are cast nodular iron. A process called fillet rolling made the use of nodular iron very reliable in the 1970's. Hot-forged crankshafts are seeing a comeback as higher cylinder pressures, rpm's in modern engines are making forgings attractive again. High-performance and diesel applications have always been forged. Modern forgings utilizing near net shapes with CNC produced forging tools designed with flow-simulation software have minimized the machining stock and optimized performance of the finished component. As engines become smaller, lighter and HP per unit weight goes up, it is critical that the rotating and reciprocating mass be reduced to their minimum. Pound for pound the hot forging still represents the best choice for the engine running gear - the crank and rods in particular.

 
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Some cranks are CNC cut. Note that they are cut from a high strength alloy billet, and not from commonly manufactured iron.

 
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Forging tends to align the grains of the metal, creating a stronger overall component. Forged parts by comparison are denser as well. (pretty pricey too)
Once a crank is formed, the journals are then cut and ground.

 
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machining is done only on mating surfaces.

 
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Most auto cranks are cast then CNC cut.

Miniature hobby motor cranks are usually CNC cut from billet.

 
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