Can I Knit Myself a Car? Or a Space Shuttle?

karbonz_dp_1I have knitting needles made from aluminum, bamboo, rose wood, and plain old wood

and as a knitter, I have come to appreciate the subtleties of using these textured needles for different yarns.

But I’m curious by nature. And when I heard about carbon fiber knitting needles, I couldn’t resist. Whenever carbon fiber usually pops up on my radar, it’s in relation to aerospace or race cars or golf clubs as a space-age material for a post-space-age world. I’ve heard about how it is lighter and stronger than steel, how it can be woven or layered into any shape required. What I hadn’t heard of is people knitting with it.

So I googled it: Knitting with carbon fiber. And sure enough I pulled up what I had in mind: slender matte needles with sleek chrome caps and tips. They are gorgeous, and I intend to own some in the near future.

But I also pulled up the other side of the coin. As it turns out, it is possible not only to knit with carbon fiber, but to actually knit the carbon fiber.

Mind boggling. In a world where knitting jewelry with gold wire is the far end of using unique materials, the idea of walking into my LYS and asking for a skein of pure polycarbosilane polymer fiber seemed a little out there.

Well, after a little research it turned out that hand knitting with carbon fiber isn’t quite there. Yet.

The whole concept is elaborated in a laconic 4 page paper written by three German scientists. They took three different kinds of silicon carbide fibers, tested them for strength and flexibility, and knit some swatches on a machine (modified for the job) that looks like this:

A 2 Tempi Racop TR6 raschel machine (LIBA Maschinenfabrik GmbH, Naila, Germany) designed specifically for laboratory testing. The maximum swatch width is 10″.

Here’s video of a full size one in action:

Now, for clarification, the type of knitting shown here is known as warp knitting while the sort of knitting we do with our skeins and needles is known as weft knitting or filling knitting. Warp knitting can only be done on machines, and produces a much flatter, denser, and less elastic fabric than traditional knitting. The specific type of knitting shown in the movie above (and used with carbon fiber) is called raschel knitting. To quote the Encyclopædia Britannica Academic Edition ‘s entry on knitting: “Raschel knits have a lacelike, open construction, with a heavy, textured yarn held in place by a much finer yarn. Raschels can be made in a variety of types, ranging from fragile to coarse, and usually have limited stretch.”

TECHNICAL TANGENT–FEEL FREE TO SKIP

From The Encyclopædia Britannica Academic Edition–Entry on Textiles
Raschel

Coarser yarns are generally used for raschel knitting, and there has recently been interest in knitting staple yarns on these machines. In the Raschel machine, the needles move in a ground steel plate, called the trick plate. The top of this plate, the verge, defines the level of the completed loops on the needle shank. The loops are prevented from moving upward when the needle rises by the downward pull of the fabric and the sinkers between the needles. Guide bars feed the yarn to the needles. In a knitting cycle, the needles start at the lowest point, when the preceding loop has just been cast off, and the new loop joins the needle hook to the fabric. The needles rise, while the new loop opens the latches and ends up on the shank below the latch. The guide bars then swing through the needles, and the front bar moves one needle space sideways. When the guide bar swings back to the front of the machine, the front bar has laid the thread on the hooks. The needles fall, the earlier loops close the latch to trap the new loops, and the old loops are cast off. Raschels, made in a variety of forms, are usually more open in construction and coarser in texture than are other warp knits.

TECHNICAL TANGENT ENDS HERE

So. Exotic materials, mammoth machines, and here’s what they found out:

For starters, carbon fiber doesn’t have the same flexibility we knitters are accustomed to with our natural, or even synthetic, fibers. It is stiff, inelastic, more like fiber glass than acrylic. If it is bent too severely, the fibers crack, and the whole thing can literally just break apart. Not great if the idea is to create something weight-bearing.

Also, when the fibers rub against each other, the friction can cause more cracks. So the carbon samples with a sizing on them which reduced friction were stronger than the sample without the sizing. To further reduce friction between the fibers, WD-40 was used.

Certain parts of making a stitch took more tension than other parts. When the tension increased past a certain point (30 cN), the fibers started to fracture, so the whole knitting process was re-evaluated to that at no point was the tension ever more than the yarn could handle.

But more than that, it’s possible. Knitting carbon fiber is possible.

So, what next? Well, the obvious answers are found where carbon fiber is already used. In airplanes and cars, sports equipment and building bridges. But what could it look like to see knitting in these things? We’ve seen what can happen when a whole sneaker is knit in one piece, what would it look like to knit a whole car in one piece? Or a canoe? Or a satellite? Could a car kit start to look like several skeins (or spools) of industrial strength yarn and a knitting loom instead of an assortment of machined parts?

Probably not. After all, here’s what it looks like when a car chassis is woven: (Incidentally, this video gives a good close up of what carbon fibers actually look like.)

So we won’t be knitting cars and space shuttles at home any time soon. But it does seem like the flying cars of the future could be knit ones.

For Further Reading/Sources:

 

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