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Carbon wrapt barrels...heat transfer...

25 Aug 2018
@ 10:00 am (GMT)

Anders Österberg

What is your opinions on carbonfiber wrapt barrels heat trasfer possibilities...?

I have a realy hard time to get my head around the annonsed high heattransfer in carbon fiber ...

It's possible that carbon fiber leads heat better than steel...I dont know..?
But then I think the outside would be very hot fast...especially when the weight-mass is so low ....

Where goes the heat ...???

In my word the thin steel-lining-barrel would be blistering hot ...💡


25 Aug 2018
@ 01:55 pm (GMT)

Andrew Murray

Re: Carbon wrapt barrels...heat transfer...
Hi Anders,

Your assumption is correct. I am sure this has come up in Nathan's books before, and on here.

But yes, essentially cooking the barrel from within.

In other industries, like car racing, exhausts are carbon wrapped to ensure no heat escapes until the very end of the exhaust pipe. The reasons are varied but the result is that the exhaust gas is very hot by the end of it.

If you have a thin barrel, wrapped in carbon, you can expect the detrimental effects of heat (such as increased barrel wear and warping) to be multiplied.

There are better ways to protect your barrel. One of them is to simply purchase a stainless barrel from the start.

Cheers mate,

25 Aug 2018
@ 05:33 pm (GMT)

Warwick Marflitt

Re: Carbon wrapt barrels...heat transfer...
Anders. Email Grant at True flite barrels
26 Aug 2018
@ 03:17 am (GMT)

Anders Österberg

Re: Carbon wrapt barrels...heat transfer...
I think the short answer is no..

Found this page

And as I understand it the carbonfiber is very good heat-conductor ..but only in one way/plane ....

In crosslayer with epoxy in between the
heat-transfer is in a barrel ...

13 Sep 2018
@ 07:54 am (GMT)

Nathan Foster

Re: Carbon wrapt barrels...heat transfer...
To anyone interested, please have a look at the following google patent page.

The page highlights the difficulties of carbon wraps or more specifically, the limitations of the epoxies used to hold the wraps in place.

This is a fairly complex subject, not the sort of thing that you would want to get into based on faith in a gun company's literature / website, not when we are paying twice the price for a wrapped barrel. Buyers need factual data, not fancy graphics. Those who get into marketing often neglect the potential of this information age. If a seller is not willing to provide information, buyers may not trust the product. This does not mean to say that in house processes need to be shared. But at the very least, some live infrared temp readings and material comparisons would be useful.

Some cut and pastes:

[0004] When a composite barrel is subjected to high heat from rapid or prolonged firing, however, they are usually less durable than solid steel barrels. Temperatures within the barrel of a semi-automatic or an automatic rifle, for example, can easily exceed 500° F, and may exceed 700° F or higher. Firearms made with barrels manufactured entirely from steel and similar materials are durable and have a sufficiently high heat transfer characteristics to dissipate heat quickly enough to accommodate such firing applications and still perform acceptably. Existing gun barrel composite shells have lower thermal conductivity in the radial direction than steel, such that the composite material effectively acts like a heat insulator. Types of steel typically used in gun barrels have a thermal conductivity of about 20-40 watts/meter-Kelvin (20-40 W/m- K). A typical PAN carbon fiber epoxy composite has a thermal conductivity of only about 0.5 W/m- K in the "through thickness" direction, or radial direction in a gun barrel application. Typical values for the "in plane" (the fiber direction) for these composites are on the order of only 1-5 W/m- K. As discussed below, PMC materials also degrade at lower temperatures than steel.

[0010] Thermal conduction within the PMC tends to be strongly affected by the orientation of fiber, being higher in the longitudinal direction of a filament than transversely across.

Depending on which specific carbon fiber is used, thermal conductivity of a PAN fiber, for example, could be higher than steel (about 20-40 W/m- K) in the longitudinal direction, but less than 10 W/ m-K in the transverse or radial direction. The resin between the fibers in the cured PMC is even less thermally conductive than the transverse thermal conductivity of the fibers. When a PMC is used as an outer shell for a barrel, solving the heat problem is difficult because most heat must be conducted radially to the outside surface of the barrel and ambient atmosphere, through the composite shell, requiring heat to transfer through resin and transversely across individual fibers.

[0011] Thermal conductivity is affected not only by the type of resin, fibers, and any additive(s) and their relative proportions, but also by the size of the fibers and size of additive particles. For example, a typical individual PAN carbon fiber might have a diameter between about 5 and 10 microns. A carbon fiber filament tow comprises a plurality of fibers, with a tow typically used for a gun barrel application having about 6,000 to 24,000 individual fibers. After the resin-coated carbon fiber tow is wound around the barrel and cured, the resin will bond all the continuous reinforcing fibers together to provide mechanical integrity and durability. Ideally the cured resin will fill essentially all of the space between the individual carbon fibers. The volume or space between the individual carbon fibers - referred to as the "unoccupied volume or space," the "inter-fiber volume," or the "interstitial space" interchangeably - is thus ideally occupied by cured resin in the PMC. At the micro level (i.e., the scale of the fiber diameter, approximately 10 microns), significant obstacles to transferring heat from the hot steel inner barrel through the PMC are the lower thermal conductivity of the resin between the fibers, heat transfer resistance at the polymer matrix-fiber interface, and heat transfer resistance at the polymer additive particle interface.
13 Sep 2018
@ 08:17 pm (GMT)

Andrew Murray

Re: Carbon wrapt barrels...heat transfer...
Really eye opening stuff, the question of why carbon wrapping is of benefit must be asked.
14 Sep 2018
@ 12:13 am (GMT)

Warwick Marflitt

Re: Carbon wrapt barrels...heat transfer...
It looks bad ass. And apparently bad ass sells. Who wants a reliable Mule when you can own a stupid Ass?
25 Sep 2018
@ 03:54 pm (GMT)

Clarrie Hall

Re: Carbon wrapt barrels...heat transfer...
Really eye opening stuff, the question of why carbon wrapping is of benefit must be asked.

How about increased stiffness?
All the girls will tell you that stiffer is better.
26 Sep 2018
@ 01:29 pm (GMT)

Warwick Marflitt

Re: Carbon wrapt barrels...heat transfer...
Here's the truthful answer lads.....
Carbon fibre wrap is good for making New Zealand Yachts to win the Americas cup. 😆😊😂


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