Rieter

Technological and economic interrelationships

Index

A high percentage of filament always has a disturbing effect. These yarns are therefore found more often in the coarse-yarn sector, and to some extent in the coarse-to-medium- yarn range. With medium-fine to fine yarns, it would be necessary to use very expensive special filament. In general, the high price of filament relative to staple fibers exerts a strong influence on costs. Economic production of fine yarns using the wrap-spinning process is therefore not possible, due to higher raw material costs. Fine stocking filaments in the 20 - 110 dtex count range are usually used.

Filaments produced from all textile polymers are suitable as the wrapping element, the most common are polyamide fiber, polyester fiber, and viscose in the form of mono- or multi-filaments. If the final yarn is to consist of only staple fibers, poly(vinyl alcohol) filaments have to be used; these can be simply dissolved out of the yarn after spinning. In relation to ring-spun yarns [5]:

  • evenness is usually rather better;
  • strength is greater, owing partly to the filament and partly to the high degree of parallel disposition and the fibers’ binding together;
  • covering power is better;
  • hairiness is lower;
  • plying can be eliminated;
  • the tendency to snarl is practically zero.

Owing to the fibers’ binding together, there is a slight wave character in the yarn, and this can be increased to the extent of an effect yarn. Splicing can be performed without problems on the rewinding machine, and sizing can usually be eliminated in the weaving mill, as also can plying.
The number of wrapping turns per meter usually corresponds approximately to a normal yarn-twist level. The filament must be rewound from the synthetic-filament manufacturers’ large packages onto small bobbins (cops); this is done on a special winding machine.
Due to the negative impact of filament costs on the economic aspect of wrap spinning, the field of application of this system is quite limited. Suessen has therefore decided to discontinue sales of ParafiL machines.