The winding technology
The soft package winding is the most important pre dyeing operation ,which directly affects not only the dyeing quality but also post dyeing operations such as rejects,wastages and poor unwinding ,thread breakages etc.Well wound is half dyed, is the popular saying which is very correct in the context of package dyeing ,because we cant expect miracles from the most advanced dyeing machinery ,if our packages are of poor quality. Although different technologies of winding when operated carefully provides satisfactory results ,but in order to insure uniformity and consistently good winding ,precise adjustment and careful maintenance of the equipment is necessary and the operators must be trained and closely supervised.
Factors like count of the yarn, angle of winding, yarn tension during winding, diameter and traverse of the package, the stability of the package, the winding ration,the compactness and size of the feed package all affect the package make up and must be considered while selecting a machine for soft package winding.Hard and soft places can occur within a single package if a poor winding is chosen ,causing some parts to dye lighter or heavier.The most compact part of any package is edges or shoulders ,where the yarn turns the corner and this is the most difficult place to wet out and to penetrate.incomplete penetration will cause will cause it to dye lighter or not at all,Cupping or crimping is the only workable solution to this problem.
The Package
The yarn to be dyed is first to be wound into a package .The weight and diameter of the package is limited by the space available between the spindles (pitch) and by the levelness obtainable when a dyeing is carried out using a particular dyestuff. The package dimensions and weight are influenced by the type and construction of yarn to be processed, class of the dyestuff , machine flow rate ,end use of the dyed substrate and package holder eg spring ,cheese or cone.
Yarn wound on SS cones
The yarn package must be stable enough ,to withstand the handling during loading, processing and unloading from the machine. It should withstand the temperature change and flow volume and flow direction of liquor. It should accommodate a small amount of shrinkage and swelling during processing with temperature increase as well as wetting
Package Holder
The package holder may be a ss dyespring ,a perforated plastic cheese (reuseable or disposable) or perforated cones made of SS or plastic.
Each and every holder type has advantages and disadvantages which are explained below,
A dyeing package is characterized by its geometry and its density profile , the bigger dia dye center has advantages over the smaller ID packages because it offers lesser resistance to the flow of liquor in case of in to out and at the same time area exposed to dye liquor is gtreater for better uniformity of the dyeing.
As a thumb rule the main objective from the dyers point of view is to get the material uniformly dyed throughout the package, the machine is used to its full capacity ,the hydro extraction and drying is done without affecting the quality of the dyed material and unwinding is trouble free.
SS Dye Springs
The dye springs are most commonly used package holder ,on which the yarn is wound offers the advantages such as these are reusable ,compressible ,making a perfect coloumn after pressing,spacers etc are not used between the individual packages ,thus reducing the possibility of channeling , dye spring offers much lesser resistance to the liquor flow through the packages. Due to the higher compression possibility the dyeing machines can be loaded to a higher capacity and liquor ratio can be reduced for better economy of the process.
