<VV> casting aluminum

[John Kepler]

Bottom line, if you were to do this, you would have them cast by a casting  
house.They know all these details. 
 
Just to inject a touch of economic reality into this, and explain a couple
of problems with all of this talk of casting a fan.  

First, a fan impeller is NOT a type of investment casting that is going to
be easy to make....the low mass requires VERY thin web-thicknesses, as well
as extreme dimensional consistency.  These requirements will generate high
reject rates, which will raise cost considerably.  Second, the low-volumes
for an aftermarket part will force anyone contemplating this into the realm
of the "Low-Volume Job-Caster".....the bottom-feeders of the metal
fabrication world!  These guys are great for making belt-buckles and cute
little yard ornaments....but not so good for a critical high-speed/high-load
automotive part that will require precise alloy integrity (which also
implies things like engineering and laboratory support that they usually
don't have!), as well as some pretty good equipment and a high-degree of
casting expertise that is HIGHLY uncommon in that group of firms (I'm being
generous....I've never found ANY low-volume job-caster that could make a
consistently decent product, but I suppose there HAS to be one out there!)

At the end of the day, and in the volumes that are reasonable to
expect.....it'll be easier and cheaper to CNC mill the fan out of billet
than cast it, with one hell of a lot better fan out the door!

John