What is Package Dyeing?
Package dyeing is a method used in the textile industry to dye yarns, typically in the form of cones, cakes or spools. This method is widely used in industries where colored yarn is needed for weaving, knitting, or other textile processes. Package dyeing provides the textile industry with an opportunity to color yarn at the latest possible stage prior to fabric manufacture. This is of prime importance if the dyer is to respond rapidly to changes in fashion and consumer demands. In order to meet these demands technical innovations have been, and are being, adopted by the textile industry to ensure that package dyeing meets not only the technical but the aesthetic requirements of the industry.
Package dyeing is generally only as good as the package preparation. There have been many discussions regarding the relevant merits of precision winding and random winding; in fact, most random split drum or traverse winding equipment will meet most package dyeing requirements.
Packages can take a variety of forms, with names such as cheeses, cones or cakes. The most commonly used type is the cheese, which is parallel sided and formed by winding the yarn on to cylindrically shaped formers.
Packages can be prepared directly from spinning machines, so that a separate winding operation is unnecessary. Staple yarns, for example, are often delivered to dyehouses on plastic formers, ready for dyeing. Uniform movement of dye liquor is essential for the production of level dyeing, and several factors can impede the flow if they are not taken into account when the package is being wound.
Achieving a successful level dyeing in a package dyeing system is highly dependent on the care taken during the preparation stage. The density of the package and its uniformity are therefore among the most influential factors in the outcome of the dyeing process. The yarn needs to be wound into a suitable form, for instance, cheese, cake, cone or rockets. Both metal and plastic formers have found use in the dyeing industry.
Package dyeing machines are available two types either as vertical loading or as horizontally loading machines.
After dyeing, packages are washed and finished properly in the same machine and taken out hydro extracted or pressure extracted in the same machine and dried subsequently.
Important Factors of Package Dyeing:
The important factors influencing the degree of levelness in package dyeing include:
- The rate of dye liquor circulation and its reversal
- The package density and the shape of the package
- The rate of dye uptake in relation to temperature, time, pH and other factors.
The most important parameters affecting levelness of dyeing in a package dyeing operation could be listed as follows:
- Package construction and shape
- Package density and porosity
- Flow rate (circulation rate) of dye liquor
- Flow direction of dye liquor in packages
- Rate and manner of dye bath exhaustion
- Rate of temperature rise
- pH of dye bath
- Presence of retarding, levelling or other chemical agents.
Advantages of Package Dyeing:
Package dyeing process is carried out in either hank or package form. Compared with hank dyeing, package dyeing enjoys various advantages, such as lower production costs as well as higher standards of levelness achieved. A high degree of reproducibility can be obtained using package dyeing. In general, these advantages may be summarized as follows:
- Reduced quantities of waste, including dye and chemicals
- Higher speeds of back winding and elimination of hank reeling
- Savings in energy, water, dye, chemicals, labour and space
- Possibility of high- temperature dyeing
- Rapid drying is possible
- Better controllability and better levelness
- Process can be readily automated.
Disadvantages of Package Dyeing:
A major disadvantage of yarn package dyeing is the introduction of two further winding stages into the overall production, which increases the time, as well as the cost of the process.
Levelness is one of the most crucial factors for the success of package dyeing. In the case of yarn package dyeing, as a result of a high dye uptake at surfaces most available to the fl owing liquor overdyeing in some regions is observed, removal of which is usually a long and costly process and in some cases almost impossible.
Automation in the dyeing industry has witnessed a rapid growth. Several fully automated systems have been introduced to the market. Some of these machines are capable of loading and unloading the dyeing vessel with the package material at a very high speed.
References:
- Textile Dyeing By Dr. N. N. Mahapatra
- Modelling, Simulation and Control of the Dyeing Process By R. Shamey and X. Zhao
- Control Systems in Textile Machines By G. Nagarajan and Dr. G. Ramakrishnan
- An Introduction to Textile Coloration: Principles and Practice By Roger H. Wardman
- Wool Dyeing Edited by D M Lewis
