After warping, some packages contain just a few grams of yarn which is unsuitable for the efficiency of further processing, such as warping, twisting, and quelling. This necessitates the preparation of a dense and uniform yarn package of sufficiently large size from unsuitable packages which can unwind in the subsequent operations without interruptions, is called rewinding.The yarn unwound from the package passes through yarn tensioned and control systems, and with the help of a grooved cylinder, is wound evenly around the package; the yarn enters the recess in the cylinder, thus the rotary movement of the cylinder corresponds to the translation of the yarn.Winding machines currently have independent heads with individually adjustable motors. A modern winding machine can process yarns ranging from a count of Ne 2 to finer ones, at a winding speed of 400 to 2000 m/min.
Winding is more than just transferring yarn from one package to another. Further functions of winding are to check the yarn and to eliminate any faults found.
Materials Processed:
Input - Yam (spinning bobbins)
Output - Yarn (large cones, tubes, etc.)
Objectives of the Process:
Ø Inspect the yarn
Ø Clearing of defects
Ø Lubricate the yarn
Ø Package the yarn
A basic diagram of winding m/c:
Fig: yarn winding
Elements of Winding:
1. Yarn withdrawal
2. Yarn tensioner
3. Yarn clearing
4. Stop motion
5. Take up
Importance of winding:
Unevenness in traditionally spun staple yarns is a natural phenomenon usually induced by the process of manufacturing (spinning). Although with modern process controls and machines many imperfections in the spun yarns can be controlled, some still remain in the final yarns. Most common of all imperfections are thin or weak places, thick places, slubs, neps, and wild fibers, as shown schematically.
During the subsequent processes of winding, warping, and slashing, not all but some of these imperfections create obstacles to steady and smooth working. Therefore, it is important to classify, quantify, and remove those imperfections which may cause the interruption of the operation. In other words, only ‘‘objectionable’’ faults need to be removed for trouble-free processing of the yarns. The ring-spinning operation produces a ring bobbin containing just a few grams of yarn which is unsuitable for the efficiency of further processing, such as warping, twisting, and quelling. This necessitates the preparation of a dense and uniform yarn package of sufficiently large size which can unwind in the subsequent operations without interruptions.
The packages prepared for warping are normally cross-wound, containing several kilograms of yarns.This implies that a number of knots or splices are introduced within each final package. Bear in mind, each knot or splice itself is an artificially introduced imperfection; therefore, the size of this knot or splice must be precisely controlled to avoid an unacceptable fault in the final fabric.
In modern winding machines, knots and splices are tested photoelectrically for size, and only acceptable knots and splices are allowed to pass on to the winding package. In modern spinning processes, such as open end, friction and air jet, the spinning process itself produces a large cross-wound package, thus eliminating the winding operation.
Functions of the Winding Operation:
Important functions of the winding operation are
1. Clearing of yarn faults
2. Making larger wound packages
3. Preparing soft packages for dyeing
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