|
Jonathan Cappola
|
|
|
Group: Forum Members
Posts: 5,
Visits: 39
|
Hi all,
I'm in the process of getting ready to pour a cylindrical tube out of epoxy or polyester resin. It is 0.5" thick walls with an ID of 14". The cast will be 30" tall and needs with withstand internal pressures of 45psi.
I have obtained metal duct work for the mold sides and an environmental chamber to cast the piece in. I'm looking for any advice on how to apporach casting something of this size (~3gal). Would I have to pour in layers or would it be possible to pour all at once? What sort of resin would be recommended for such a task?
Thank you,
Jon
|
|
|
|
|
Lester Populaire
|
|
|
Group: Forum Members
Posts: 311,
Visits: 13K
|
+xHi all, I'm in the process of getting ready to pour a cylindrical tube out of epoxy or polyester resin. It is 0.5" thick walls with an ID of 14". The cast will be 30" tall and needs with withstand internal pressures of 45psi. I have obtained metal duct work for the mold sides and an environmental chamber to cast the piece in. I'm looking for any advice on how to apporach casting something of this size (~3gal). Would I have to pour in layers or would it be possible to pour all at once? What sort of resin would be recommended for such a task? Thank you, Jon So you want to build a pressure vessel of a substantial size out of resin only? this seems like a very dangerous idea to me...
|
|
|
|
|
Jonathan Cappola
|
|
|
Group: Forum Members
Posts: 5,
Visits: 39
|
+x+xHi all, I'm in the process of getting ready to pour a cylindrical tube out of epoxy or polyester resin. It is 0.5" thick walls with an ID of 14". The cast will be 30" tall and needs with withstand internal pressures of 45psi. I have obtained metal duct work for the mold sides and an environmental chamber to cast the piece in. I'm looking for any advice on how to apporach casting something of this size (~3gal). Would I have to pour in layers or would it be possible to pour all at once? What sort of resin would be recommended for such a task? Thank you, Jon So you want to build a pressure vessel of a substantial size out of resin only? this seems like a very dangerous idea to me... It is a low pressure application. I ran a handful of tensile tests per ASTM D638 on some epoxy I had on hand to get some idea of the elastic modulus and the yield strength. The hand calcs and the FEA suggest that its quite safe up until about 60 PSI assuming I can pour the bulk without any notable defects under the loading conditions we've prescribed. I am, however, not sure how to approach such a large cast as most epoxy resin casting I do is for sample holding for nanoindentation as those are very small molds (1.25" OD cylinders).
|
|
|
|
|
Lester Populaire
|
|
|
Group: Forum Members
Posts: 311,
Visits: 13K
|
+x+x+xHi all, I'm in the process of getting ready to pour a cylindrical tube out of epoxy or polyester resin. It is 0.5" thick walls with an ID of 14". The cast will be 30" tall and needs with withstand internal pressures of 45psi. I have obtained metal duct work for the mold sides and an environmental chamber to cast the piece in. I'm looking for any advice on how to apporach casting something of this size (~3gal). Would I have to pour in layers or would it be possible to pour all at once? What sort of resin would be recommended for such a task? Thank you, Jon So you want to build a pressure vessel of a substantial size out of resin only? this seems like a very dangerous idea to me... It is a low pressure application. I ran a handful of tensile tests per ASTM D638 on some epoxy I had on hand to get some idea of the elastic modulus and the yield strength. The hand calcs and the FEA suggest that its quite safe up until about 60 PSI assuming I can pour the bulk without any notable defects under the loading conditions we've prescribed. I am, however, not sure how to approach such a large cast as most epoxy resin casting I do is for sample holding for nanoindentation as those are very small molds (1.25" OD cylinders). technically it should be quit an easy pour as the wall thickness is rather small so heat dissipation should not be an issue with a casting resin. however, epoxy is really brittle which is bad for pressure tanks as the damage tolerance is very small. energy is force times pressure which shows that your low pressure application still contains about a tenth of the energy of a hand grenade. wouldn't wanna be anywhere near that thing when pressurized.
|
|
|
|
|
Jonathan Cappola
|
|
|
Group: Forum Members
Posts: 5,
Visits: 39
|
+x+x+x+xHi all, I'm in the process of getting ready to pour a cylindrical tube out of epoxy or polyester resin. It is 0.5" thick walls with an ID of 14". The cast will be 30" tall and needs with withstand internal pressures of 45psi. I have obtained metal duct work for the mold sides and an environmental chamber to cast the piece in. I'm looking for any advice on how to apporach casting something of this size (~3gal). Would I have to pour in layers or would it be possible to pour all at once? What sort of resin would be recommended for such a task? Thank you, Jon So you want to build a pressure vessel of a substantial size out of resin only? this seems like a very dangerous idea to me... It is a low pressure application. I ran a handful of tensile tests per ASTM D638 on some epoxy I had on hand to get some idea of the elastic modulus and the yield strength. The hand calcs and the FEA suggest that its quite safe up until about 60 PSI assuming I can pour the bulk without any notable defects under the loading conditions we've prescribed. I am, however, not sure how to approach such a large cast as most epoxy resin casting I do is for sample holding for nanoindentation as those are very small molds (1.25" OD cylinders). technically it should be quit an easy pour as the wall thickness is rather small so heat dissipation should not be an issue with a casting resin. however, epoxy is really brittle which is bad for pressure tanks as the damage tolerance is very small. energy is force times pressure which shows that your low pressure application still contains about a tenth of the energy of a hand grenade. wouldn't wanna be anywhere near that thing when pressurized. I'm decently confident in the engineering analysis to determine its safety. It will be operating at about 10PSI on average. Do you think I could use an epoxy resin and pour it all at once or should I consider layering the pours? Would polyester resin be a better option if I wanted to pour the entire thing pretty much at once?
|
|
|
|
|
Jonathan Cappola
|
|
|
Group: Forum Members
Posts: 5,
Visits: 39
|
+x+x+x+x+xHi all, I'm in the process of getting ready to pour a cylindrical tube out of epoxy or polyester resin. It is 0.5" thick walls with an ID of 14". The cast will be 30" tall and needs with withstand internal pressures of 45psi. I have obtained metal duct work for the mold sides and an environmental chamber to cast the piece in. I'm looking for any advice on how to apporach casting something of this size (~3gal). Would I have to pour in layers or would it be possible to pour all at once? What sort of resin would be recommended for such a task? Thank you, Jon So you want to build a pressure vessel of a substantial size out of resin only? this seems like a very dangerous idea to me... It is a low pressure application. I ran a handful of tensile tests per ASTM D638 on some epoxy I had on hand to get some idea of the elastic modulus and the yield strength. The hand calcs and the FEA suggest that its quite safe up until about 60 PSI assuming I can pour the bulk without any notable defects under the loading conditions we've prescribed. I am, however, not sure how to approach such a large cast as most epoxy resin casting I do is for sample holding for nanoindentation as those are very small molds (1.25" OD cylinders). technically it should be quit an easy pour as the wall thickness is rather small so heat dissipation should not be an issue with a casting resin. however, epoxy is really brittle which is bad for pressure tanks as the damage tolerance is very small. energy is force times pressure which shows that your low pressure application still contains about a tenth of the energy of a hand grenade. wouldn't wanna be anywhere near that thing when pressurized. I'm decently confident in the engineering analysis to determine its safety. It will be operating at about 10PSI on average. Do you think I could use an epoxy resin and pour it all at once or should I consider layering the pours? Would polyester resin be a better option if I wanted to pour the entire thing pretty much at once? Sorry for double posting. The cast will also simply be the cylinderical tube wall. The end caps are machined steel plates with tie rods providing a clamping force on the cylinder.
|
|
|
|
|
oekmont
|
|
|
Group: Forum Members
Posts: 550,
Visits: 27K
|
Why does it have to be cast? A simple laminated tube would be multiple times stronger, cheaper and lighter. I absolutely agree, that this is a dangerous idea. Theoretically the resin is quite strong, but in real life there is internal stress from the curing, etc. And epoxy is far to brittle. you wouldn't use glass either, I think.
|
|
|
|
|
Jonathan Cappola
|
|
|
Group: Forum Members
Posts: 5,
Visits: 39
|
+xWhy does it have to be cast? A simple laminated tube would be multiple times stronger, cheaper and lighter. I absolutely agree, that this is a dangerous idea. Theoretically the resin is quite strong, but in real life there is internal stress from the curing, etc. And epoxy is far to brittle. you wouldn't use glass either, I think. It is required to be a clear polycarbonate or similar material and the acrylic tubes at this size are a couple thousand dollars whereas the same resin cost is about 200 dollars. Again, could a non epoxy resin be a viable choice?
|
|
|
|
|
oekmont
|
|
|
Group: Forum Members
Posts: 550,
Visits: 27K
|
Epoxy is by no means a similar material to polycarbonate. That would habe been a descent choice for your application.
If you really want to cast it, and it has to be clear transparent, I guess epoxy (with a slow hardener) would be your "best" option. Polyester usually has even greater problems with internal stress from curing. And everything else won't be transparent. Again, I consider it highly dangerous and would absolutely not try it myself.
|
|
|
|
|
Matthieu Libeert
|
|
|
Group: Forum Members
Posts: 955,
Visits: 3.4K
|
+xEpoxy is by no means a similar material to polycarbonate. That would habe been a descent choice for your application. If you really want to cast it, and it has to be clear transparent, I guess epoxy (with a slow hardener) would be your "best" option. Polyester usually has even greater problems with internal stress from curing. And everything else won't be transparent. Again, I consider it highly dangerous and would absolutely not try it myself. Like above, I don't think it is a safe thing to do. epoxy would be your best choice. pouring this in a transparant clear way without bubbles will be extremely difficult with resins. Have you thought on how you will even demould the inner tube? Resin will tend to shrink and make it pretty hard to remove the inner tube without breaking it. have you thought of the post-cure of your epoxy as well? I'm a big believer in trying things that haven't been done before but keep it safe. epoxy is strong when used with a matrix but very brittle as well and shatters in sharp shrapnel like glass. theoretical an practical approach in strength are in many times far off. small bubbles or curing cracks will weaken the epoxy a lot compared to labo-tests in best conditions where manufacturers aim for the highest results for their products. Like in the comments above, comparing it with making a grenade is a good comparison 
Founder MAT2 Composites X Sports
website: www.mat2composites.com  
|
|
|
|