Mechanical Spinning

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Mechanical Spinning

Mechanical spinning is the drawing out of an assembly of staple fibers to the desired thickness and inserting twist to impart the necessary strength to the yarn. In a mechanical spinning process the end product is a single yarn.

The two major mechanical spinning systems are:

Ring spinning/Ring Mechanical Spinning:

Since the Industrial Revolution the most popular system for spinning any kind of yarn has been the ring spinning system. It involves the feeding of a relatively thin, low twist rope of fibres (called a roving) into a system of rollers (dafting rollers), which thin out the fibre stream before it is twisted and wound onto a package (bobbin). The important point of this system is that the spindle (on which the bobbins sits) rotates very quickly as it must insert the twist, as well as wind on the yarn. The twist is inserted along the length of yarn between the last pair of drafting rollers (the delivery rollers) and the point at which it touches the bobbin.

To help in this, the yarn is threaded through a traveller (of a weight related to the tex of the yarn) which plus the yarn, balloon around the restraining ring. The limitations on this system are the balloon tension (which increases as spindle speed increase) and the maximum speed at which the traveller can slide on the ring without overheating and wearing. Spindle speed may be increased as ring size is reduced (decreasing tensions, etc.) but this also decreases package size, which means more knots needed in final package and more frequent doffing (removing of the bobbin when it is too full and will hit the ring). Since the Industrial Revolution the most popular system for spinning any kind of yarn has been the ring spinning system. It involves the feeding of a relatively thin, low twist rope of fibres (called a roving) into a system of rollers (dafting rollers) which thin out the fibre stream before it is twisted and wound onto a package (bobbin). The important point of this system is that the spindle (on which the bobbins sits) rotates very quickly as it must insert the twist, as well as wind on the yarn. The twist is inserted along the length of yarn between the last pair of drafting rollers (the delivery rollers) and the point at which it touches the bobbin. To help in this, the yarn is threaded through a traveller (of a weight related to the tex of the yarn) which plus the yarn, balloon around the restraining ring.

The limitations on this system are the balloon tension (which increases as spindle speed increase) and the maximum speed at which the traveller can slide on the ring without overheating and wearing. Spindle speed may be increased as ring size is reduced (decreasing tensions, etc.) but this also decreases package size, which means more knots needed in final package and more frequent doffing (removing of the bobbin when it is too full and will hit the ring).

Open-end spinning/ Open-end Mechanical spinning:

Due to these limitations, a new system of spinning has been developed which relies on a different principle. Actually, it is not new, as it is one of the most ancient methods of spinning yarn and still carried out by primitive tribes around the world. It involves the end of the yarn being rotated and fibres added onto it to continue the yarn. The primitive method is to roll the yarn end along the thigh to twist the new fibres on, then wind onto a package. Also using this principle is the classical spinning wheel of the Middle Ages.
The new name for this type of spinning is “Open End” coming from the fact that it is the tail end of the yarn that the fibres are added to and twisted. There are various methods for spinning yarn using this principle. At Yarraville, we have Rotor Open End machines. This involves the tail end of the yarn being whirled around rapidly in the rotor. Fibres are fed into the rotor and as the tail of the yarn sweeps onto a package, which can be of any size or shape because it does not have to rotate.

Also because the fibres are delivered in an opened state, there is no need for the extra processing required to produce a roving. A sliver direct from the draw frame is sufficient to feed the Open End machine. There is no need for knots to join breaks, as the fibres will just join the old yarn in the usual way.

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