Forged Crankshaft Tech

摘要

Ever wonder how a forged crank is made? Here we take a look at materials, the forging process and hardening methods. A brief overview of how crankshafts are manufactured, including cast, forged and billet cranks. FORGED CRANKSHAFTS. Aftermarket crankshaft manufacturers often employ their own proprietary formulas, but generally speaking, a steel ingot is heated in an oven to about 2,200° F (at which point the steel is very malleable/formable...not yet a liquid, but very easy to move around and shape). The hot ingot is then placed into a forging die and squeezed into the approximate shape of the desired crank profile. This "squeezing" is performed either by a hammering or pressing process. Either way, the goal is to compress the alloy mix not only to precisely fill the die, but also to increase the strength of the alloy by compacting the molecules and aligning and strengthening the grain structure. Basically, the size of the ingot is much larger than the volume required in the die (generally, a crank maker will start with an ingot that weighs about twice as much as the desired final product). During the forging/compacting process, the excess material is forced out of the die at its mating lines. This excess is later sheared off in a trimming die.