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DIY GUY
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Hi
I have a project to construct a carbon fibre reinforced rifle barrel, these are commercially available at a hefty price. My plan is to take an existing barrel turn in down in the lathe to a require dimension then build it back up with carbon to an over size to maximise the rigidity and strength while not including the weight of steel.
I see my best option is to use a single tow varying the angles with each layer ie 90, 45, 45, 30, 30 degrees etc, over all laminate thickness will be between 5 - 6.5mm
My questions is would you recommend a wet lay up dipping the tow through a resin bath or a pre preg layup ?
Regarding pre preg (something I have never worked with before) how critical is the baking temps and times ? Do you have to use a special oven or is there other options ?
I see you have out of oven pre preg materials - does this mean it can be cured with out baking ?
Any advise would be greatly appreciated.
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oekmont
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First of all: I think that any other fibre angle than 0 degree is pretty much wasted material on a rifle barrel. You want to stop it from bending, not from twisting.
There are out of autoclave prepregs, but no out of oven prepregs. For a rifle barrel, out of autoclave prepreg will give you the advantage (over regular autoclave prepreg) that the curing temperatures are generally lower, and you want to keep heat out of the process as much as possible, because the steel will shrink while cooling down, the carbon will (almost) not, so any dysbalance in your laminate will result in a deflection of the barrel.
For out of autoclave prepreg you only need an temperature controlled oven and a vacuum pump. For you application a regular oven might work, because you will have no mould side, and therefore not pinhole problems.
Even less heat would be involved if you wrap the barrel in a wet layup. Another option might be to glue a cured carbon tube onto the barrel.
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DIY GUY
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+xFirst of all: I think that any other fibre angle than 0 degree is pretty much wasted material on a rifle barrel. You want to stop it from bending, not from twisting. There are out of autoclave prepregs, but no out of oven prepregs. For a rifle barrel, out of autoclave prepreg will give you the advantage (over regular autoclave prepreg) that the curing temperatures are generally lower, and you want to keep heat out of the process as much as possible, because the steel will shrink while cooling down, the carbon will (almost) not, so any dysbalance in your laminate will result in a deflection of the barrel. For out of autoclave prepreg you only need an temperature controlled oven and a vacuum pump. For you application a regular oven might work, because you will have no mould side, and therefore not pinhole problems. Even less heat would be involved if you wrap the barrel in a wet layup. Another option might be to glue a cured carbon tube onto the barrel. Hi thank you for the information, its very well received. So from what you have told me I would be best to use a unilateral cloth running the length of the barrel ? Would this lay up suit a vacuum infusion better ? also do you know what is the maximum number of layers or combined material thickness for a vacuum infusion ? Thank you in advance.
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Buchado
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+x+xFirst of all: I think that any other fibre angle than 0 degree is pretty much wasted material on a rifle barrel. You want to stop it from bending, not from twisting. There are out of autoclave prepregs, but no out of oven prepregs. For a rifle barrel, out of autoclave prepreg will give you the advantage (over regular autoclave prepreg) that the curing temperatures are generally lower, and you want to keep heat out of the process as much as possible, because the steel will shrink while cooling down, the carbon will (almost) not, so any dysbalance in your laminate will result in a deflection of the barrel. For out of autoclave prepreg you only need an temperature controlled oven and a vacuum pump. For you application a regular oven might work, because you will have no mould side, and therefore not pinhole problems. Even less heat would be involved if you wrap the barrel in a wet layup. Another option might be to glue a cured carbon tube onto the barrel. Hi thank you for the information, its very well received. So from what you have told me I would be best to use a unilateral cloth running the length of the barrel ? Would this lay up suit a vacuum infusion better ? also do you know what is the maximum number of layers or combined material thickness for a vacuum infusion ? Thank you in advance. Hi Diy guy. With infusion and prepreg you can achieve a greater fiber do resin ratio than wet lay up. If you have all the tooling for infusion, go for it. There is hardly a limit on the maximum number of layers for infusion, it's hard to say because it's a very piece/layup depending process, it depends on the shape, where you out your inlet and outlet lines, the resin viscosity, the flow media you'll use among other things, each case is a case, can't say for sure how much resin or if the laminate will be properly impregnated until you try. If it will be a one off piece, I would go for prepreg.
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Warren (Staff)
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Something Like that could be done pretty similarly to a mandrel wrapped tube - except the mandrel is the barrel and it is not removed. As already said, UD fabric down length of barrel and a single woven outer layer for durability and cosmetics is a good approach.
Mandrel wrapped tubes can be done with good results wet lay up with a shrink tape. The shrink tape will provide a lot of consolidation. Of course you can go to out of autoclave pre-preg too for good results.
In both cases you would want some kind of post cure, especially if it is a gunpowder based firearm (as opposed to an air rifle) due to heat generated during repeat firing.
Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant
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DIY GUY
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+xSomething Like that could be done pretty similarly to a mandrel wrapped tube - except the mandrel is the barrel and it is not removed. As already said, UD fabric down length of barrel and a single woven outer layer for durability and cosmetics is a good approach. Mandrel wrapped tubes can be done with good results wet lay up with a shrink tape. The shrink tape will provide a lot of consolidation. Of course you can go to out of autoclave pre-preg too for good results. In both cases you would want some kind of post cure, especially if it is a gunpowder based firearm (as opposed to an air rifle) due to heat generated during repeat firing. Hi Warren Thank you for the input it's very much appreciated. I'm definitely leaning towards the wet lay up, what are your thoughts on an infusion for this, or a wet lay up then vacuum bag ? Any advantages or disadvantages ? I have an infusion kit purchased from you guys which I'm using for rifle stocks with great results Also where would be the best place to find information on post curing as you are correct this is a gunpowder based firearm.
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Matt (Staff)
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Hi, Warren's off today so I thought I'd pitch in on his behalf. Personally, I think this project would be made a lot more difficult using either infusion or wet-lay processes, as opposed to oven cured prepreg. The reason for this is simply because of how easy and straight forward it would be using prepreg and the 'cure' would take care of the 'post cure' that you'd really need to do on a wet-lay or infused laminate anyway (to get the higher temperature stability you need). To do this project using prepreg, you would need little by way of materials, time or equipment and it would be easy to achieve a very good result in terms of mechanicals and aesthetics. Using prepreg, the process would be: - Key the outer surface of the metal barrel
- Use our XC130 undirectional prepreg, aligned length-ways down the barrel. Apply pressure using a flat plate to consolidate the prepreg tightly onto the barrel and keep 'rolling' until you achieve the desired thickness.
- Switch to a layer of our XC130 210g woven finish prepreg for the outer layer. This is a much more durable surface for the outside of the barrel (UDs can 'splinter').
- Wrap the barrel tightly using our composites shrink tape. This special tape contracts at temperature and will consolidate the prepreg during cure.
- Put the carbon wrapped barrel in an oven. Precise temperature control would not be necessary, you could probably just start from cold and switch it up in a couple of steps to a final cure temp of 120C.
- Cool, remove the wrap and do any final finishing you want. The finish will be good already, with slight ridges from the overlaps on the tape.
This really would be the easiest way! I hope this gives you some food for thought at least. It's not to say that wet-lay or infusion aren't possible and you may still choose to go that way but this is one of those projects that would almost do itself if you take the most suitable route. All the best, Matt
Matt StathamEasy Composites / Carbon Mods - Technical Sales
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