These intermediate process between spinning & weaving on loom, which converts the yarn in suitable form that can be used for weaving, are called Weaving Preparetory Process.
The process used in the manufacture of WRAP & WEFT are called ‘ Wrap Preparatory Process’ & ‘ Weft Preparatory Process’ respectively.
Wrap Preparatory Process
The process to be used depend upon the type & quality of yarns, the type of fabric to be produced, & also on the equipment & other facilities available in the mill. The process flow chart is given below which shows the various stages of wrap preparation. The solid lines indicate the basic process most commonly used & the dotted lines indicate some additional processes required for different types of fabrics.
Windings : In the process, the yarn from a number of ring frame bobbins or hanks is put in a long continuous length on to a bigger packages such as Wraper’s bobbin, cone or cheese. During this process, the objectionable faults are removed from yarn. For the use of dyed yarn, ring frame bobbins may be taken to reeling process to obtain hanks. These hanks are dyed 2 & then sent to winding. The yarn is dyed in cone/cheese form also. Thus, winding packages ( wrapers’ bobbin, corn or cheese ) are taken to next process of wraping i.e. Direct Wraping or Sectional Wraping.
( DIRECT WRAPING OR BEAM WRAPING )
The object of wraping is to collect a predetermined number of single end packages (winding package from which a single thread comes out on unwinding) & convert it into sheet form with ends uniformly spaced & wind a specified length on to wraper’s beam. Thus at the end of process, we get a multiend package (package which on unwinding give no. of ends) i.e. wraper’s beam wound with a sheet of uniformly spaced (hundreds of) ends of specified length. To have a sheet, the wraper’s beam is subjective to dyeing to get dyed wrap.
( SECTIONAL WRAPING AND BEAMING )
Sectional wraping consists of winding of wraping of number of sections, each wound with a (narrow) sheet of uniformly spaced, predetermined number of ends of equal length side by side. on collecting ends from all sections, we get required number of ends required for weaving. Beaming consists of winding sheet, obtained by collecting ends from al sections, on weaver’s beam. Thus, at the end of the process, we get weaver’s beam which may be sent to loom or for drawing-in.
Sizing: Wrap thrads are subjeced to considerable stresses, strains & rubbing action duration weaving. So wrap threads are impregnated with size whose main constituent is on adhesive substance. The size binds the fibres in the yarn surface to resist stresses, strains & rubbling action without breaking. At the back of sizing machine, wrap sheets form number of wraper’s beam are combined to obtain a single sheet containing required number of ends for weaving. This sheet is impregnated with size, dried & wound on weaver’s beam. Thus, at the end of sizing, we get weaver’s beam which may be sent for drawing in or to loom.
Drawing-in & denting :- This process consists of passing ends of wrapsheet from weaver’s beam through heald eyes of healdshaft & throught dents of reed. On loom, if exactly the same fabric is to be prodused after a weaver’s beam is exhausted, then the new sheet of wrap threads is connected end by end to the old sheet. This operation is called tying-in or twisting depending upon the method of joining. Thus, this process need only weaver’s beam wound with wrap. But if other type of fabric is to be prodused after a weaver’s beam is exhausted, then we need weaver’s beam with wrap drawn & dented. Old beams with its heald shafts & reed is removed & new beam is & heald shafts & reed reset on the loom.
Wrap Preparatory Process
The processes of Reeling,Hank dyeing,Winding & cone/cheese dyeing are same as discussed earlier.The end package of weft ring spinning frames are directly used in the shuttle.This type of weft is known as direct weft.The yarn from ring frame bobbins is subjected to Winding/Cone or Cheese dyeing.The yarn from bigger packages(Cone/Cheese or Warper’s bobbin) (from which objectionable faults are removed/may be dyed too) is wound on to pirns by means of pirn winding.These pirns are supplied to shuttle looms.