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The forging process begins with a steel ingot that’s heated to approximately 2,400 degrees F, to the point of creating an almost Jell-O-type consistency. (photo courtesy Pacific Forge)
With the near-molten steel placed in a forging die, a hammer press slams the die with about 240,000 lbs. in not one but multiple steps. (photo courtesy Pacific Forge)
Once the hammering process is complete, the raw forging is ready to be extracted from the die. (photo courtesy Pacific Forge)
A claw removes the raw forging from the lower die half. (photo courtesy Pacific Forge)
The claw picks the crank up at the area where excess steel has oozed out from between the die halves. This is then trimmed off in a shearing operation. ( photo courtesy Pacific Forge)
Raw forgings ready for machining. (photo courtesy Pacific Forge)
After tempering, the cranks are finish-machined. (photo courtesy Scat)
Tempering (heating and cool down) is handled in a controlled furnace. (photo courtesy Bryant)
Some cranks are also treated to a cryogenic-tempering for added strength. (photo courtesy Bryant)
Surface-hardening, such as ion-nitriding, is done by exposing the cranks to an ammonia/nitrogen mix, where nitrogen reacts with the surface, creating a hardened surface. Hardening depth is controlled and dictated by the specific manufacturer. (photo courtesy Bryant)
Here a finished crankshaft is inspected for profile using a sophisticated profilometer. (photo courtesy Bryant)
Stress-testing confirms the crank’s metallurgical strength. (photo courtesy Bryant)
Billet cranks begin with forged round bar stock. photo courtesy Bryant
Finished forged cranks ready for inspection. (photo courtesy Bryant)
A finished forged crankshaft is a thing of beauty. This example has been gun-drilled for weight reduction. (photo courtesy Scat)
This thermal image shows a batch of forged cranks being nitrided. The process creates surface hardening throughout the entire surface of the crank, not in isolated areas, such as would occur with induction-hardening. (photo courtesy Scat)
A forged crank being precision CNC finish-machined at Lunati’s manufacturing facility. (photo courtesy Lunati)
A forged crank being finish-ground. (photo courtesy Lunati)
A finished forged crank from Lunati. (photo courtesy Lunati)
Tags: CRANKSHAFT, FORGINGS
