# Tool Talk > Machines >  Forging crankshafts GIF

## Jon

Forging crankshafts GIF. Anyone know more about this process? Are the crankshafts being press forged, or just heated and then pressed? Is that considered press forging? More importantly, when he uses the tongs to flip over the crankshaft, is anyone else thinking "rack of ribs"?  :Cool: 



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Previously: turning a giant crankshaft

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dubbby (Apr 20, 2020),

KustomsbyKent (Jun 19, 2017),

richardcrane (Jun 19, 2017),

Seedtick (Jun 19, 2017),

Toolmaker51 (Aug 11, 2018),

Trojan Horse (Jun 21, 2017)

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## Frank S

Jon just like forged steel wrenches the crankshafts start out as nothing more than a billet of metal its composition depending on manufacture's specs which can be simple cast iron to an exotic alloy, in each stage of the process the molecules are being compressed closer and closer together until their density is many times that of the original billet. The tighter the molecules are compacted the stronger the end product. 
There are sometimes several different types of machines used in the forging process the first 2 or 3 may be hammer forges, the final stages more of the press type although their speed may be such that they may appear to be hammer forges as well from the observer's point of view. After tempering One final step would be to reheat to a predetermined temperature these processes were not shown in the video however the in the very last scene where the dies pressed down on the crankshaft one final time this was to straighten the shaft and make sure that it would pass the indicator testing sequence before being sent to the grinders.
Another way to make crankshafts is to use a rolled cylindrical billet then machine away everything that does not look like a crank shaft then place it in a holding fixture put it in an oven for heat treatment then to the grinder this being an extremely expensive process but routinely done when making one off exotic or prototype crankshafts

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greenie (Apr 15, 2021),

Jon (Jun 19, 2017),

KustomsbyKent (Jun 19, 2017),

mcthistle007 (Apr 19, 2021),

Toolmaker51 (Jul 29, 2019),

Trojan Horse (Jun 21, 2017)

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## Frank S

One thing I forgot to mention in the forging process is the oil passages must be bored before the tempering and hardening process

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greenie (Apr 15, 2021),

mcthistle007 (Apr 19, 2021),

Toolmaker51 (Jul 29, 2019),

Trojan Horse (Jun 21, 2017)

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## Toolmaker51

> One thing I forgot to mention in the forging process is the oil passages must be bored before the tempering and hardening process



And that process supposedly begat the split point drill. Up to that time splash oiling was considered a satisfactory option.

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