PRECISION WINDING OR SPINDLE WINDING:
In precision winding, the package gets driven positively. The package is mounted on the spindle having positive drive. When the spindle gets rotated, it pulls the yarn and yarn gets wound on the yarn package. The coils of yarn get formed with the help of yarn traverse guide. This yarn traverse guide helps to move the yarn at very high speed from one end to another end of package. Thus coil formation takes place. Traverse guide makes to and fro motion with the help of a cam. In precision winding successive coils of yarn are laid close together in a parallel or near parallel manner. It gets commonly used for filament yarn yarn winding.
The spindle winding process avoids the chances of yarn rupture during winding process.
The yarn elongation during winding gets increased in this winding process.
The package resulted in this process has higher winding density.
The yarn package getting resulted in spindle winding has higher higher weight of the yarn on package due to higher winding density.
The precision winding package poses poor stability during unwinding and handling.
The rate of unwinding rate of yarn in spindle winding package is lower due to poor package stability.
STRUCTURE AND WORKING PRINCIPLE OF PRECISION WINDING MACHINE:
The common components of precision winding and their working are given below:
In the precision winding machine, the package is mounted onto a spindle which is driven positively. The supply bobbin is mounted on the creel. The yarn passes through a tension device then it passes through a yarn traverse guide. When the spindle rotates, it revolves the yarn package at high speed. The traverse guide carries the yarn from one end of package to the other end of package thus it provides to and fro motion to the yarn. As the diameter of the package increases, the spindle speed is decreased in same proportion to maintain constant winding tension.
In the precision winding system, yarn package revolves directly. A spindle is fitted to the machine which is driven positively. When the package diameter increases, the yarn winding speed increases gradually. This increased winding speed generates high tension during winding process. It causes yarn breakage during process of winding. This process necessitates variable speed of spindle to maintain constant surface speed of yarn package. The differential gear box or digital inverter drive is used to keep yarn winding rate constant.
YARN TRAVERSE GUIDE:
The traverse guide performs the reversing of the yarn from one end to other end of package. Traverse guide moves in to and fro direction on its path. This motion of traverse guide is repeated continuously during winding. The yarn passes through it traverses with guide. Thus yarn coils changes the position on the package.
There are several different independent traverse systems, but the simplicity of the wing cam makes it a useful example to describe. The end, of a yarn guide bar moves the yarn while the other end is made to move around the periphery of the cam, traveling one circuit of the periphery per revolution of the camshaft. As rear end makes one circuit of the cam, upper end reciprocates, moving the yarn through a return traverse along the length of the bobbin. The reciprocating yarn guide limits the winding speed because of the inertia on reversals. A very high rate of traverse is impeded by the mechanics of the guide system, since forces of 16 to 64 times the weight of the yarn guide can be present during the reciprocating action.
ADVANTAGES OF PRECISION WINDING:
The main advantages of precision winding are given below:
• There is no chance of yarn rupture.
• The flanges on the packages are not required.
• The larger package size can be produced.
• Side unwinding is possible.
• The turns per inch (degree of yarn twist)
• The more compact package results in precision winding.
• It is mostly useful in winding of filament yarn.
DISADVANTAGES OF PRECISION WINDING:
The disadvantages of precision winding machine are as follows:
• The speed of winding machine is limited because of limited speed of yarn traverse guide
• Chances of yarn elongation are possible.
• Package stability is less.
• Unwinding of yarn is little difficult.
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