Talk Composites - The Forum for Advanced Composites

which resin type is the best for my structural casting?

http://www.talkcomposites.com/Topic3975.aspx

By marco guerrini - 12/26/2012 8:39:44 PM

Hello,
I am currently looking into manufacturing a turgo water turbine runner by gravity casting a resin into a mould I have made, to form individual cups which I will then attach to a hub. 

Here is an image of a much smaller version (about 3 times smaller) of the item I wish to cast.
http://www.renewablecomponents.com/hydro.html

I was wondering if you could recommend the type of resin you believe to be most suited to my needs.

The part will be gravity cast in a steel or plastic mould.
The application of the runner will require water resistance.
The shape of the casting is a turgo cup (almost like a very large ice cream scoop) with a short 10cm handle

The runner is essentially an impule turbine constantly being shot with a jet of water to produce a torque. Large water jet will cause approx 400N force on a cup.

Thickness of the cup is around 15-20mm but depends on the strength of the material used.
approx. 200mm long cup
Outdoor use
High strength
low friction surface finish
Structural component subject to cyclic loading
high hardness due to sediment erosion
temperature range during use of -10degC to +35degC
minimize cost
subject to large bending moments and tensile load.
Hopefully will last for around 15 years.

Thank you for your time. Any thoughts on the best resin to use would be invaluable as I have limited experience with resin casting. 

Best wishes
Marco Guerrini 
(University of Bristol student)
By Matt (Staff) - 1/2/2013 8:59:46 AM

Hi Marco,

Thank you for your post.

Your list of requirements for this casting resin is quite long and you might find it difficult to satisfy all of these criteria in a standard 2-part thermoset casting resin. Some if the properties you're after are more like those of a structual thermoformable plastic (injection moulding) and less like those of a typical casting resin. You will need to look into some quite specialist polyurethane vacuum casting resins, the like of which we don't currently supply. You'll need to cast them under vacuum (so in a vacuum casting machine) but if you're a university student I expect you'll have access to such a machine.

I'll PM you with some contact details of some people who might be able to help.

Best regards, Matt