Carbon fiber polymer casing
- Thread starter Roboss
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mcb
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It would probably work for one firing just fine. But for this application I can see several problems.
Carbon fiber is so stiff (modulus of elasticity is ~2.3 Gpa, compared to steel at ~2.0 Gpa and Brass at ~1.0 Gpa) is would likely not obturate well to seal the chamber, especially in lower pressure cartridges. Steel case suffers this to a lesser degree.
Carbon fiber typically fails in a brittle manner, where soft steel, aluminum, and brass currently used in cartridges fails in a ductile manner. This failure mode means when carbon fiber when if fails, such as a case head failure, it would create more high velocity fragment than soft steel or brass.
It would probably not reload well since it would not really resize well as it have very little plastic deformation before permanent damaged. The act of firing it would ablate some of the resins used to hold the fibers together on the inside surface again causing problems for reloading.
Making the cartridge would be costly. If you simply take a bar of carbon fiber and cut a cartridge shape out of it (straight wall would be doable) you have cut much of the carbon fibers weakening the case significantly. You would need to really lay up the cartridge on a mandrel so you reach very close to net final shape with little or not machining to cut as few fibers as possible. This would be very hard/expensive to do for bottle neck cartridges.
It's all doable but I don't see much advantage. It's also not really needed with cases like True Velocity coming along quite nicely.
-rambling.
Carbon fiber is so stiff (modulus of elasticity is ~2.3 Gpa, compared to steel at ~2.0 Gpa and Brass at ~1.0 Gpa) is would likely not obturate well to seal the chamber, especially in lower pressure cartridges. Steel case suffers this to a lesser degree.
Carbon fiber typically fails in a brittle manner, where soft steel, aluminum, and brass currently used in cartridges fails in a ductile manner. This failure mode means when carbon fiber when if fails, such as a case head failure, it would create more high velocity fragment than soft steel or brass.
It would probably not reload well since it would not really resize well as it have very little plastic deformation before permanent damaged. The act of firing it would ablate some of the resins used to hold the fibers together on the inside surface again causing problems for reloading.
Making the cartridge would be costly. If you simply take a bar of carbon fiber and cut a cartridge shape out of it (straight wall would be doable) you have cut much of the carbon fibers weakening the case significantly. You would need to really lay up the cartridge on a mandrel so you reach very close to net final shape with little or not machining to cut as few fibers as possible. This would be very hard/expensive to do for bottle neck cartridges.
It's all doable but I don't see much advantage. It's also not really needed with cases like True Velocity coming along quite nicely.
-rambling.
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Zerodefect
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Checked pricing on kayak paddles recently?
Boeing and Airbus are making wings with carbon fiber. Ever see the size of those up close? It's drastically driving up the price of quality carbon supplies. Unless I missed supply catching up with demand, this idea sounds expensive.
Why not use some sort of mold-able polymer? Or some sort of woven protein instead of the carbon fiber?
Boeing and Airbus are making wings with carbon fiber. Ever see the size of those up close? It's drastically driving up the price of quality carbon supplies. Unless I missed supply catching up with demand, this idea sounds expensive.
Why not use some sort of mold-able polymer? Or some sort of woven protein instead of the carbon fiber?
243winxb
Member
Since the carbon fiber casing cannot handle deformation and expansion resultant of detonation , I would expect some degree of shattering.
Ever try to pick carbon fiber slivers out of your fingers? I have. Nasty.
I would also be concerned about tiny shards of carbon becoming airborne. If that ever got into the lungs I doubt it would come back out.
Ever try to pick carbon fiber slivers out of your fingers? I have. Nasty.
I would also be concerned about tiny shards of carbon becoming airborne. If that ever got into the lungs I doubt it would come back out.
Put silicosis to shame.....nasty thought....
edwardware
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Polymer, sure. Carbon fiber reinforcement is almost exactly the wrong set of properties for this application.
Jim Watson
Member
The True Velocity/Gendye plastic cartridge is white and I wonder if it is not something common and cheap like polyethylene or polypropylene.
mcb
Member
I talked to the True Velocity guys at AUSA in DC last year. The are making them white simply because its easier and less costly. They can add colorant to make it nearly any color the customer wants. I don't know for sure as they were playing the polymer type close to the vest but I believe the polymer is in the same family as polyethylene given the feel and their claims of easy recycling of the spent cases. I could be wrong.
Jim Watson
Member
Yes, appearance and recycling was what I was going by.
"Magnetically retrievable," too; so the head insert is steel. Cheap.
"Magnetically retrievable," too; so the head insert is steel. Cheap.
243winxb
Member
https://patents.google.com/patent/US9546849B2/en
Old news- Lightweight polymer ammunition cartridge casings. https://www.tvammo.com/
Google-
Old news- Lightweight polymer ammunition cartridge casings. https://www.tvammo.com/
Google-
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Any reason they don't offer handgun cartridges? What using this for revolvers?
herrwalther
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243winxb
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None i can think of. Pressure is lower in handguns. Should work?
The military ammo most used is 5.56 & 7.62. I have not see any government contracts for any polymer cased ammo.
The whole ammo processing methods would have to be changed. My guess.
Cost.
Even if the cost difference was minimal few would buy it because it’s not reloadable.
For military applications reducing cartridge weight by 30% has huge benefits. For someone carrying a 6 shot revolver reducing cartridge weight by 30% wouldn’t even be noticed.
It is too new? I'm thinking that they want this to be well tested first. After all metallic cartridges have been around since the what the 1840's. Looking at the website, I quickly noticed the developers don't list a lower cost advantage to using polymer casing.
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