Heavy count yarns – the problems with heavy carbon and glass

When most yarns were used for ordinary textile applications, standard forms of splicer were sufficient. For normal textiles, the maximum count has been normally about 1000 tex. Now counts are getting bigger, especially in the composites business.

As yarn count increases, it is necessary to form a splice with large number of filament wraps. The splicing chamber must be wider, the splice longer, and the air flow greater. High counts demand big splicers.

But splicing carbon and glass poses additional problems; making a bigger splice is not enough, because brittle filament are easily destroyed by the air blast. The designer is faced with an impasse:

  • He needs to create many wraps.
  • With a high-modulus fibre, he needs to raise the air pressure, to persuade the filaments to wrap.
  • With a brittle fibre, he cannot apply the pressure sufficient to generate the required geometry without breaking filaments.

These requirements seem incompatible. But Airbond tried new approaches, which involved making a discrete number of splices, side-by-side, at a defined spacing. Excellent splices can be made by using three splice actions, making a triple-splice about 100mm long, at a lower air pressure than would be used for a single splicing chamber. Splice appearance is good and strength excellent – up to 95% of parent yarn strength. Low pressures ensure that carbon, in particular, is largely undamaged. Already, counts exceeding 15000 tex are being spliced successfully.

Airbond is now doing active research into the splicing of much bigger products - in excess of 100,000 tex. This research is far from complete, but we consider that the technical problems have been solved.