Anyone out there know of any dissolvable core materials other than the Advanced Ceramic Research materials: Aquapour & Aquacore? I’ve tried both of these but they are too fragile for our use. We even sent our molds to ACR for them to try to make it work at their facility in Tucson, but struck out. We are making pump impellers and would like to make a one piece closed impeller with the internal water passages created with a dissolvable core.
I wonder if alum. foundry core sand would work for you???
There is a process that uses sand, liquid sodium silicate & carbon dioxide gas. It is water soluble but I don’t know how environmentally friendly the sand slurry is when it is washed out. I haven’t tried it yet but thanks for reminding me. The core will have to be well sealed (probably several coats of pva) so the resin doesn’t penetrate the sand and so the surface is as smooth as possible. Do you know of anyone who has used this method in composites?
What are you trying to make the impeller out of? There are ways to make a core disappear, but really need to know what you are making the impeller out of.
Try Ti International, Their web site is under construction but you can contact
them at:
TI International Ltd.
2260 Commonwealth Ave.
N. Chicago, IL USA 60064
Phone: (847) 689-0233
Fax: (847) 689-0238
Email: jo@tiinternational.com
Web Site: www.tiinternational.com
Sales Contact: J.A. Krotz, jo@tiinternational.com
Engineering Contact: Scott Templeman, scott@tiinternational.com
They make cores out of nitriding salts that are dissolvable with hot water.
I found them after I was unable to make ACR stuff work as well, very cost
effective too.
Cheers
Jim
Scooter & Jim, thanks both for the replies.
Scooter: the impeller will be made from vinyl ester resin, filler and glass reinforcement.
Jim: Thanks for the Ti International info, I’ll definitely look into it. I had searched for ‘salts’ but couldn’t turn anything up. Right now I’m testing the method I mentioned above with sand & liquid sodium silicate. This will work but there are some features I would like to reproduce more precisely than the sand gives resolution for. If I may ask: what are you making?
If you are using the foundry sand, get the fineset grit you can. You will need to post cure/cook to get the foundry sand to break and fall out after the part is made.
TEST, TEST…and you will get it!
Keep us informed of your progress!
If you can keep the temperature down, try using wax. Make a mold to form the wax into the shape you need.
Geppetto,
We had to make some CF prepreg ducts that needed to be one peice
and finished on the inside. They have salts that can be used to cure
350º F prepreg on. The surface finish of the salt is like that of a good
plaster finish. We had the mandrels cast in epoxy/glass tools that we
made here. The tools for the casting need to be able to take some heat
since the salt is melted to make the casting. they sell the raw material if
you want to do it yourself. But I would suggest letting them make the
mandrels for you, at least in the begining. They will come to you released
and ready to go. If your parts have a hi tolerance you will want to be careful
with calculating for the CTE of everything in the chain. But Ti can help with all of that.
Sorry about the vageness of what we made but there is a bit of confidentiality to it.
I hope this helps
Cheers
Jim
Scooter,
I did try wax but our crossections in the core are too thick for wax only (we get sink areas). It’s possible I could try a surface wax coating by pouring in molten wax into the core mold then rotating the mold all around to coat the inside surface, then fill in behind with another filler (also dissolvable) to support the wax. It will be down on the list of methods to try, I’d like to find something a little less labor intensive. Thanks, keep the ideas coming!
Do you have a pic of the impellar? Does it have to be made with VER? Have you looked into cast urethane?
Scooter,
We can use other resins however we want to eventually produce in VE resin for the chemical resistance. Regardless of the resin used, I haven’t found the core material that works for us. Attached is a photo of a generic closed impeller (ditto Jim’s ‘confidentiality’ comments-can’t show the impeller I’m working on), the water passages that the core will form curve in two planes: from front to back and from center to outside, changing crossectional dimension as it goes (hope that makes sense) , kind of a squarish corkscrew shape passage.
Jim, thanks for the TI International info, got samples coming.
Man, that is a tough one!
It can’t be made in 2x parts and pressure seal / chemicial welded together with an epoxy resin?
It is tough! I’ve done it a couple of times but the core material I was trying is too temperamental and I couldn’t get consistant good cores with it, hence resurrecting the ‘dissolvable core’ thread. We can bond the parts together, however the market does not yet have a one piece closed impeller…know what I’m saying?
How about stereolitghthy (?) construction?
Or a local Alum foundry was bought out several years ago and the new owners are techy people from like Cal tech or MIT which invented a new CNC sand plotting system for alum castings…which may work with???
My first thought is it might be expensive but it’s worth a look, want to pass along any contact information?
The foundry is in Santa Ana, just off the 5 Freeway & 17th exit. It was named ARPM foundry (Ken Lowry) for too many years but now…?
I’ll ask on another forum to see if anyone knows the new name but I’m not planning to go that way for some time as I was just by there the other day…figures!
Or better yet, one of my foundry reps use to work there and might know it’s new name. I’ll see later today…