Due to increased business from the commercial jet market (Boeing 787, Airbus 380 and others) the military jet market (Raptor and others) as well as very strong demand from recreational products, marine, musical instruments, automotive parts and many other products, have made 3K carbon fiber tow (3000, 5-7 micron thick filaments per yarn bundle) expensive and difficult to purchase.

The carbon fiber manufacturers have not been able to build capacity fast enough to meet demand nor does the manufacturing efficiency of 3K vs. other tow size such as 12K or 24K warrant a large effort to increase 3K supply when the carbon fiber production lines can produce more pounds of other sizes that are also in very large demand.

3K tow is the basic building block to weave low aerial weight fabrics such as 200 gsm (6 oz/yd2) 2x2 twill or plain weave fabrics which have a very nice aesthetic appeal in clear coated composite parts. There are many products that use 3K fabric simply for "the carbon look".

(1) Dyed or colored glass yarns. These have potential but result in a less dramatic aesthetic appeal.

(2) Heavier woven fabric made with 6K tow input yarns. Some of these fabrics are quite good aesthetically but result in heavier more expensive parts as 6K is also short in supply and the price for these fabrics has increased by over 50% in the last 2 years.

(3) Spread tow technology: This has been Core Composite's focus for the past 6 months. Working with weavers from Europe, Asia and now North America, a line of products is coming to the market that meets or exceed the weight and mechanical property requirements of many 3K fabric customers. Although not as aesthetically appealing as 3K, these new 6K and 12K spread tow fabrics allow the weaver to meet aerial weights as low as 50 gsm (1.5 oz/yd2) with excellent coverage (low gaps) and a variety of weave styles such as plain weave and twill. Some of these fabrics are a bit loose and "fall apart" during the cutting process so the weavers are developing chemistries that can be applied to improve handling.

Below you will find some data comparing traditional 200 gsm 3K fabric vs the new 12K spread tow fabrics. As you can see, almost every mechanical property is improved; especially impact. The wet out and drapeablilty are quite good. The material can be made into prepreg also.

We recommend that 3K users try some of these new spread tow fabrics that are now economically priced to compete with 3K (the weaving process is slower at this time with spread tow technology although the input fiber price is significantly lower so the cost is offset). We recommend that you use what little 3K that will be available over the next two or three years strictly for aesthetic applications. We need to "preserve the resource" while improving the quality of our parts by developing alternative solutions to what appears to be a long term supply shortage of 3K carbon fiber.

Core Composites is working with knit fabric suppliers using spread tow technology to develop lower cost, higher quality stitch bonded unidirectional fabrics. We have some very nice quality 400 gsm, +-45 fabrics and we hope to have 300 gsm +-45 by the end of 2006 made with spread 12K.

Call Core Composites for sample swatches of dry fabric or prepreg and prices for a variety of supply solutions.

Click here to see Penetration Impact Test Results (3K vs. 12K)