How Are Pirns Wound?
Pirns are weft bobbins placed inside a shuttle in shuttle weaving. As the shuttle travels back and forth across the width of the shuttle loom, the yarn is unwound form the prin through the eye or slot of the shuttle. Simply said, pirns are rods onto which thread is wound for usage in weaving. They differ from bobbins as they are rods that taper at one end. Moreover, they are fixed in place, and the thread is delivered off the end of the pirn, instead of the center. Pirns are generally made of wood or plastic, and are tapered for most of their length, flaring out more sharply at the base that fits over a pin in the shuttle. Pirns are basically of three different types — plain tapered pirns, full-base pirns, and pirns with partly-formed base. Although pirns are used with end delivery shuttles, they became highly popular with the development of the flying shuttle. If you are looking for the best kinds of pirns, Trim Engineering Services is where you can go to as they are one of the leading Pirn Manufacturers in India, who have been manufacturing and supplying pirns and other textile machinery parts to clients across the globe since the past 30 years!
The dimension of a pirn is controlled by the dimensions of the shuttle it needs to be placed in. Whatever the dimension, the pirn has to be long and thin. The supply packages are bigger than the delivery package in pirn winding, unlike that as in cone winding. Moreover, as the yarns in pirns are already cleaned from slubs and other faults, no additional yarn cleaning operation is required in pirn winding.
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Now, let us take a look at the process of pirn winding in detail. Winding of a pirn is different from the regular winding process of cones and cheeses. In case of regular winding, the cross-wound package results in lots of tension variation during weaving, and parallel wound package results in instability. This is why pirn winding includes overlapping short, conical, and cross-wound sections. A pirn has a conical base, from where the prin winding begins, slowly proceeding towards the tip of the pirn. In pirn winding, the yarn is transferred from a larger package to the smaller pirn. Here, the traverse mechanism does not go back and forth along the package. Instead, it only builds yarn on one part of the package at a time. This means that contrary to bobbin winding, where bobbins are wound evenly from end to end, pirns are wound from the base forwards to ensure snag-free delivery of the threads. This type of winding maintains uniform tension and reduces ballooning effects, thus reducing the possibility of slough-off.
There are special automatic machines used to wind pirns that are known as pirn winding machines that consist of spindles. In such machines, when a prin is filled, it is automatically removed from the spindle, and replaced with an empty pirn, thus allowing uninterrupted weaving. All types of cotton filament yarns, silk yarns, terrycot yarns, woolen yarns, and synthetic fiber yarns can be wound using automatic pirn winding machines.
