<VV> RE: Corvair Fan (Kent Sullivan): Material Selection

[Fran & Mary Marchand]

Kent,  My company had a "special" project to replace Delrin, which was 
being eaten by a mild acid.  We went through an extensive (read as 
multi-million $ DoD spending) material selection, design, manufacture 
and test process.  We finally settled on PEEK (polyether-ether-ketone) 
for the part.  PEEK is a very high temperature material, extremely inert 
and very strong.  It comes in many flavors, including fiberglass and 
carbon reinforcements.  Its one drawback is that it is expensive as a 
raw material.  For building a fan, a major cost will be in the mold 
design/manufacture process.  The material cost may be secondary if the 
quantities are fairly low.  PEEK raw material is made by Victrex in the 
UK (http://www.victrex.com), but is widely availble around this country.

Fran

>>If all goes well, we would like to make the production fans out of 
>>something much lighter than aluminum; perhaps a modern plastic. (But it needs to be
>>one that doesn't react with battery acid fumes. We all know the story of 
>>the prototype Delrin fan creating formaldehyde gas!) There will be a
>>price/performance decision to make.
>>    
>>