If you think about it, crankshafts are really treated badly. I mean – along with the heat – the forces they must endure are pretty extreme. So I wonder: How they are made?
I guess if I was going to make one myself, I’d use a casting technique. I’d make a mold, pour in the metal, then fine tune the surface and dimensions with machining, followed by case hardening. But it seems like some kind of forging technique might be better. I’m not even sure a cast crank shaft could even stand up the forces at all. Casting produces a more brittle product than forging, and it seems like a brittle crank shaft is not what you want. You don’t want it shattering and pieces going flying in all directions.
On the other hand, crankshafts have such a complicated shape, it seems like it would be close to impossible to bend a rectangular bar of steel into the shape of a crankshaft by pounding on it.
Just curious. Anybody know how crankshafts are made by the auto manufacturers?