Rieter

The operation of the licker-in

Index

By far the greatest part of opening and cleaning is performed by the licker-in. In machines with only one licker-in, opening is performed to an extent where more than 50% of all fibers pass onto the surface of the  main cylinder in the form of tufts, and slightly less than 50% in the form of individual fibers. Treatment imparted by the licker-in is therefore very intensive, but unfortunately not very gentle. The licker-in combs through a fairly thick fiber fringe at a rotation speed of 1 600 rpm (approximately 600 000 wire points per second), a circumferential speed of around 21 m/sec (approximately 76 km/h) and a draft of more than 1 600. Even without sophisticated mathematical computation, it will be clear that fiber deterioration is very likely to occur at the opening point. Only the degree of deterioration can and must be precisely controlled by adjustment of:

  • the thickness of the batt;
  • the degree of openness of the raw material in the feedstock;
  • the spacing between the operating devices;
  • the degree of orientation of the fibers in the feedstock;
  • the aggressiveness of the clothing;
  • the rotation speed of the licker-in;
  • the material throughput.

Opening itself involves the tearing away of the feed batt on a wedge shape by means of the licker-in; 'wedge shape' refers to the fact that the projecting fiber fringe becomes steadily thinner where it faces away from the clamping point owing to the plucking-out of fibers. The type and intensity of the opening process influences the final yarn, primarily as regards neppiness, imperfections, evenness and strength.