Great answer Bryant. I would add that cold forging is superior because it eliminates voids and provides better grain structure. High quality aircraft castings are typically rated 1/3 lower in strength than comparable forgings for structural analysis.
> Donald Gillies wrote:
> What is melt-forging and is it still used?
> The "Mighty" series of cranks were cold forged. "Melt Forging" is actually a
> marketing name for high pressure casting. The alloy is forced into the mold
> under high pressure (over 10,000 psi) and then cooled quickly with a water
> jacket around the mold. The Hierarchy for crank manufacturing is: Cold
> Forged, Hot Forged, Gravity Cast, Melt Forged.
> What separates all these process is the amount of money needed for tooling &
> the time needed to complete a part. Cold forging requires the highest number
> of dies, Hot forging uses fewer and Gravity casting & melt forging only one
> mold but melt forging is quicker.
> Hope that helps.
> Bryant Bainbridge
> Portland Oregon