Spinning is a series of operations by means of which a mass of textile fibres (staple), initially in disorder, can be arranged into one very long unit (yarn).
There are multitudes of spinning processes which vary according to the characteristics of the fibres to process and to those of the yarns one wants to obtain. The different phases of the process are complex and aimed at achieving a high quality, regular, and resistant yarn with minimum hairiness.
Cleaning and mixing cotton, trying not to break the fibres, is the purpose of this first phase. After the bales are opened, near the machines, the cotton is put in the loaders to start the stripping process. The staples, cleaned of soil, leaves and seeds, are taken to the carding machine through pipes.
The staples undergo additional refining which starts adjusting the count. The fibres begin to be parallel and the first semi-finished product is made: the sliver. The spinning cycle can now take three different paths depending on the end product one wants to make:
- the combed spinning cycle (for high quality yarns up to Ne 200/1);
- the carded spinning cycle (for average quality yarns up to Ne 40/1);
- the open-end spinning cycle (for low quality yarns up to Ne 30/1).
Select the fibres according to length. This is the purpose of combing, with all the short fibres and impurities having the same destiny: elimination. Two grips take a few centimetres of interlining (several slivers of card) that is subject to a series of combs mounted on a cylinder.
The short fibres are eliminated with the impurities while the long fibres, homogeneous and silky, form a more regular sliver.
Subjecting a certain quantity of fibres to straightening means making them slide one on top of the other so they are arranged in a volume, on a surface or in a longer length.
With this operation the sliver is gradually refined and the final result is the yarn. From the next refining cycles we obtain the roving which is twisted slightly to create sufficient resistance for unwinding but not enough to impede the straightening actions.
Once the roving is prepared with the count wanted, final spinning follows which straightens the roving to the extent necessary and which carries out the final twisting of the fibres together to produce the yarn at the count wanted.
For the first time in the history of spinning is a new process that has been developed in recent years and which privileges the properties of the yarn and not productivity.
Compact spinning produces a new yarn structure which makes it possible to reach significant results. First of all the quality of the yarn itself: a structure that is perfect, strong, with minimum hairiness and a good resistance to abrasion. This reflects on the fabrics that are shinier with distinct chromatic contrasts, resistant and extremely comfortable. The economic aspects are certainly not to be underestimated either, with high, efficient productions, improved use of the raw material and a reduction in processing costs and in the quantity of product applied in sizing. To conclude, even attention to ecology is at the fore, with reductions in the size that needs to be eliminated and in the fibrous dust in the environment plus the possibility of not having to wax.
The last phase of spinning is to wind the yarn on a tube that can be either cylindrical or conical in shape. Winding has the following objectives:
- to form a big package (normally weighing from 1 to 2 Kg) which is also easy to unwind;
- to eliminate the flawed points (or cuts), those where yarn resistance drops below a set limit;
- to eliminate shorts in the yarn as well as neps (fibrous knots) whose dimensions exceed a set limit.
The advantages of a perfect winding are basically twofold:
- maximum yield of the following processes due to the high length and resistance of the yarn (each time there is a break in the feeding yarn there is an interruption in work which requires correcting before it can be started again);
- maximum quality of the product due to the regularity of the yarn and to the continuity of the process (interruptions in work cause flaws in the product).