Carbon fiber: Everyone’s seen it and if you’re involved in the world of aftermarket tuning, you may have even attached a few parts made from CF to your car. But in all reality, how much do you actually know about the stuff? Hopefully, I’ll be able to shed some light on this fantastic gear in this short article.
In my experience, even the most hardcore performance enthusiast knows very little about carbon fiber, even though they may have their entire car draped in the stuff. As for me, I formerly worked as an aircraft technician in the Australian Army on Blackhawk helicopters, and if there’s one thing about helicopters, it’s that they’re made from a shitload of CF. So you could say I have a bit of experience working with it.
So firstly, let’s go over the basics as to what exactly carbon fiber is.
THE BASICS
Funnily enough, carbon fiber is made almost entirely of carbon, which is one of the more common elements on earth – in fact, most of your body is carbon-based.
The ‘fiber’ part in the name comes from the way the material is formed, into extremely thin strands, or filaments. These are then woven together in a tight criss-cross fashion to form what looks like a sheet of black cloth, which is the base material that almost all carbon fiber items are made from. Below is a picture of what these sheets look like before they are actually formed into something, like a bonnet for your car perhaps.
Now if you ever get the chance to pick up a sheet of this carbon fiber cloth, you’ll notice that it feels just like an almost-plastic piece of flimsy fabric, which in essence is exactly what it is. At this stage, carbon fiber is extremely weak and you can pull the strands apart quite easily with your own hands.
In order to give carbon fibre the strength that it’s known for, it needs to be bonded, or ‘cured’, using some kind of adhesive; usually an epoxy resin. Once the resin is applied and it sets, the carbon fibre will harden, giving it the inherent strength it is known for.
WET CARBON FIBER
There are two main ways of creating carbon fibre. The first way is similar to making fibreglass; basically, sheets of carbon fibre are layed on top of each other, or in a mold to create a shape such as a car door, and resin is painted over every layer like glue, bonding the carbon sheets together. This is then left to dry and harden, creating (hopefully) whatever part it was you set out to make. This is the method used to make most carbon fibre items sold on the market today such as carbon bonnets and spoilers, and is generally referred to as ‘wet’ carbon fibre, as a wet resin must be applied before curing.
Wet carbon fiber items can be made well, though are not the most ideal items when speaking in terms of CF. They will still be much stronger and stiffer than steel, however there is a better option which we’ll talk about in a moment.
Also, with a lot of cheaply-made wet carbon items such as bonnets, you’ll find that only the top layer of the item is actually carbon fiber – the underside is usually a fibreglass base, with carbon on top. In a case like this the item is more for the look of having carbon fiber, not really for the strength it could provide. Although while teamed up with the fibreglass base it will be light, don’t count on it to be as strong as an item made entirely of wet carbon, and nowhere near as durable as the stuff we’re going to talk about next…
DRY CARBON FIBER
This way of making CF items is generally much more expensive and time consuming, however produces a much stronger end-product. Instead of applying the resin to the carbon fibre sheets as they are layed out, the carbon fiber actually comes with the resin pre-impregnated in it. It’s not fully hardened, or ‘cured’ yet, so the sheets are still malleable, enabling you to craft it into the shape you want to make.
This type of carbon sheeting is sometimes known as ‘pre-preg’ carbon fibre, coming from the fact that the resin is already pre-impregnated in the sheets themselves.
You still need to lay several sheets over the top of each other, but as they already contain the resin needed for bonding, no additional resin is needed as with wet carbon. The sheets will adhere to each other, though only slightly, so some pressure is required when attempting to bond the sheets together.
Once the desired shape is made, the carbon part is then placed into a large vacuum bag which then has all the air sucked out of it, placing a large amount of pressure on the sheets helping to bond them together further. This vacuum-bagged part is then placed in a large oven, which is cooked for around twelve hours (depending on the part), melting and setting the resin and creating an extremely strong carbon-fiber part. This is called ‘dry’ carbon fibre, as no excess wet resin is needed to craft the item.
As you can see with dry carbon fiber, the process is much more in-depth, though the results produced are much more spectacular than the cheaper version. When I first made a dry carbon part out of only a few sheets, I tried just about everything to break it, from standing on it, to placing it on top of two bricks and jumping on it, but nothing could make it even flex. It’s really some hardcore stuff.
As far as its strength and impact resistance is concerned, a good dry carbon part will be around 5-8 times stronger than steel – depending on the grade – and many times lighter. But the thing is with carbon fiber, when it finally does give out and fail, it usually does it in a most spectaular manner.
WHEN IT ALL FALLS APART…
When I was in the defence force back in my old land of Australia, the base I was posted on was the scene of an accident that involved one of our Blackhawks clipping a tree and going down at around 160 kilometres per hour. Around the site, an area of around ten square kilometers was declared as a biohazard zone; when it went down, a large part of the CF items and panels failed, meaning they basically exploded into millions of tiny carbon shards – some so small that they could have been directly inhaledby some unfortunate individual and shredded their lungs.
But it’s not just that they can be inhaled; once a cured carbon item has been broken, the edges become jagged and razor-sharp, posing another great danger to human life.
Because of this, many countries have totally outlawed the use of aftermarket carbon fiber on cars, yet they still allow it when it comes fitted from the factory, on cars like the new BMW M3. The reason being is that in an accident, your car could be turned into something of a slice-and-dice weapon that could cause much more destruction than it normally would without CF parts.
MAKING THE RIGHT CHOICE
In all reality, unless you’re building a car just for use on a track, creating a full-fledged racing car or possibly even an S2000 made entirely of the stuff like the one below, you’ll most likely never need the benefits that true dry carbon can provide. If you’re just after the kick-ass look of a carbon fiber part, there’s nothing wrong with going for the wet carbon stuff, even if it is backed by fibreglass.
But if you are going after a really high-quality CF item for your car, make sure you do a bit of research into the product you’re buying before you fork over the cash. Most CF items out there are of the carbon-over-fibreglass variety and many manufacturers of these parts rely on the ignorance of buyers to make them think they’re getting something they’re really not.
I’ve seen many carbon part companies spouting absolute bullshit when it comes to selling their parts. For example, one I hear a lot from so-called ‘performance’ CF part makers is that their items are hand-made, or the layers are hand-layed, or some other verbal diarrhoea like that, and it usually comes from the ones peddling cheap, CF-coated fibreglass products. Sure, a bonnet made with a fibreglass backing and a few layers of CF sheet on top may be hand-layed, but I’d prefer to buy a machine-made dry carbon item anyday. Just make sure you know what you’re buying.
So, if you’re just wanting to get the cool JDM-bling look that CF can offer your car, then there’s absolutely nothing wrong with going for a wet carbon item, even if it is backed by fibreglass. On the other hand, if you want the extra rigidity that can be gained by adding some carbon fiber parts to your car like a fender, strut-brace or even a roof, then you really need to invest in the dry carbon item.
This is only the tip of the iceberg when it comes to CF and I’ll probably write some more about it later, though I’m not sure there’s much more you’d need to know if you’re just a motoring hobbyist. My main piece of advice here is just be sure what you’re buying when it comes to carbon fiber parts, as you generally have to fork out a lot of your hard-earned folding stuff to get some.
- Leon.
