Worsted Spinning Process
Worsted Spinning:
The scouring process consists of a series of tanks/bowls holding warm water with soap and alkali and a series of forks or rakes to push the wool through the tanks. The level of soap and alkali is reduced at each subsequent tank and the last tank generally contains only water to rinse the wool before it is fed into a dryer. The suint, which has been removed in the scouring process, is a natural form of lanolin and often sold to cosmetic companies by the Scorers. Radio frequency dryers were popular in the 1970/1980s, but most plants today use conventional hot air dryers and the main technological issue is to avoid over-drying.
Worsted Yarn Spinning Process:
Worsted spinning refers to using a worsted technique, which produces a smooth yarn in which the fibers lie parallel. Roving and wool top are often used to spin worsted yarn.
All process of worsted spinning are described briefly:
Blending:
Blending is carried out at this stage to ensure uniform properties of the yarn; to reduce variation in fabrics; to exploit the peculiar characteristics of each component of the blend to the full; and to reduce cost. It is rare to dye at the fiber stage in the roller-drafted system and so blending is carried out in large bins into which the fibers are fed through pneumatic pipes and a rotary spreader, which horizontally layers the fibers down the full length of the bin. They can therefore be removed to the carding machine in vertical layers giving more blending power. This is a large-scale process, but not as interesting to the design technologist as blending in the woolen/condenser system, so we will not spend a lot of time on this. The important issue is that the blender ensures as homogenous a mix/blend as possible.
Carding:
The Worsted carding system uses roller and clearer and is a bigger and longer machine than was described for short-staple spinning but not as long as in the woolen/condenser system, which also uses roller and clearer carding (Figure-2). This is an appropriate place to describe the fundamental technology used in roller and clearer carding. The objectives of this process are to disentangle the clumps of wool fiber, to remove any burrs and other vegetable matter, and to continue the blending process. The main disentangling takes place between the teeth (wires) of the cylinder or swift and the workers using a point-topoint action (Figure-3). To move the fibers through the process, stripping rollers are used to remove or strip the fibers from the workers through a point-to-back action and these are in turn stripped by the cylinder or swift by the same action. Finally, a fancy roller is used to raise the fibers out of the swift using a back-to-back action, so that they can be formed into a wide fibrous web. The actions are brought about due to the direction of the teeth or wires on the various roller types and their relative surface speeds.
At the end of the Worsted card, the web of fibers is condensed into a rope-like structure called a sliver (as in the short-staple system), which is then coiled into a can for delivery to the drawing stage.
Drawing:
Drawing on the Worsted system uses roller drafting as discussed for short-staple and a number of slivers (often called doublings) are fed in to continue the blending process. The main difference between a short-staple drawbox and a Roller Drafted spinning gill box is the steel pinned combs that act exactly like a comb being drawn through your hair (Figure-4). These control the fiber movements and are very effective in orienting the fibers all in the same direction (parallelizing).
Combing:
The carded slivers are fed through two or three of the gill boxes and are then fed into a Worsted combing machine. As with short-staple spinning, the combing machine uses a technologically complicated process. As design technologists, we do not need to study this process, but rather it is important that we understand that it is used to remove short fibers (known as noil) from the slivers to allow the processing of the highest quality worsted/ roller-drafted yarns with as little evidence of hairiness as possible.
Top Making:
This stage consists, once again, of a gill box at the delivery end of which the sliver is wound/coiled into a self-contained and easy-to-transport ball top of around 3–5 kg or packed into a large 25–30 kg bump top. Both forms are then transported to the fiber preparation for spinning stages. Nowadays, the conversion of raw material to a combed top form is mostly carried out in a separate mill to the fiber preparation and spinning mill. Sometimes the tops will be dyed before delivery to or at the spinning mill.
Drawing:
This process also uses gill boxes (though at this stage they are usually called drawboxes). There are normally three drawing/gilling stages used at this stage with progressively finer toothed combs and increasing drafts. The main difference is that an auto-leveling system is used on the second and third box to continuously alter the draft through the speed of the back rollers. If the slivers get heavier, the back rollers are slowed down giving more draft and if the slivers are lighter, the back rollers are speed up giving more draft. By this means, the linear density of the emerging sliver is kept as even as possible.
Roving:
This is very similar to the speed frame/roving process described for short-staple spinning. Again, a sliver is fed in to the back rollers of a roller drafting system and aprons are used to control the movement of fibers in the drafting zone. The linear density (count) of the sliver fed to the roving machine will be in the region of 10 kilotex and a draft of around 10 will be used to reduce the count of the sliver to 1 kilotex. At this linear density, a small amount of twist is required to provide cohesion to the roving, which is what the sliver is now called and this twist is also of importance to help in the drafting of the roving down to the required linear density at the spinning process.
Spinning:
Worsted spinning frames are very similar to short-staple frames, using roller drafting, aprons to control the fibers during drafting and a ring and traveler system to insert the required amount of twist and to wind the yarn onto a tube. Winding onto cones and folding or twisting into two ply yarns is carried out as for all conventional yarns.
Worsted yarns are spun on any kind of spinning machine – mule, ring, cap, or flyer. The two principle systems of spinning worsted yarns are the English system and the French system. In the English system (Bradford), the fiber is oiled before combing, and a tight twist is inserted. This produces smoother and finer yarns. The more tightly twisted yarn makes stronger, more durable fabrics. In the French system, no oil is used. The yarn is given no twist; it is fuzzier, and therefore suitable for soft worsted yarns.
References:
Like the short-staple system, this form of conventional/traditional spinning takes a long time to go from fiber to yarn and combing is again used to remove short fibers and to achieve the optimum degree of fiber alignment/orientation along the yarn axis. A major difference from short-staple spinning is the use of scouring (washing) at the beginning of the process when using natural protein fibers such as wool for which the system was first intended. When the wool arrives at the Scouring plant, it is likely to have been classed into the general quality it belongs to. The classing system most commonly used was promulgated by the U.S. Department of Agriculture, and the higher the number, the finer the quality. For example, fine quality merino wool would be classed from 60s up to perhaps 76s and sometimes a little higher and the diameter of these fibers would be between 22 and 18 μm. The wool at this stage is full of impurities, which must be removed at the early stages of fiber preparation for spinning. Natural secretions are suint (sweat) and grease. The fine the fiber, the more of these natural secretions will occur (e.g., a fine merino may hold as much as 8%–10% suint and 30% grease). These will be removed at scouring, but other acretions such as kemp (dead fibers) bugs, dirt, and vegetable matter must be removed at blending or at carding.
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| Figure-1: Scouring process of wool |
Worsted Yarn Spinning Process:
Worsted spinning refers to using a worsted technique, which produces a smooth yarn in which the fibers lie parallel. Roving and wool top are often used to spin worsted yarn.
All process of worsted spinning are described briefly:
Blending:
Blending is carried out at this stage to ensure uniform properties of the yarn; to reduce variation in fabrics; to exploit the peculiar characteristics of each component of the blend to the full; and to reduce cost. It is rare to dye at the fiber stage in the roller-drafted system and so blending is carried out in large bins into which the fibers are fed through pneumatic pipes and a rotary spreader, which horizontally layers the fibers down the full length of the bin. They can therefore be removed to the carding machine in vertical layers giving more blending power. This is a large-scale process, but not as interesting to the design technologist as blending in the woolen/condenser system, so we will not spend a lot of time on this. The important issue is that the blender ensures as homogenous a mix/blend as possible.
Carding:
The Worsted carding system uses roller and clearer and is a bigger and longer machine than was described for short-staple spinning but not as long as in the woolen/condenser system, which also uses roller and clearer carding (Figure-2). This is an appropriate place to describe the fundamental technology used in roller and clearer carding. The objectives of this process are to disentangle the clumps of wool fiber, to remove any burrs and other vegetable matter, and to continue the blending process. The main disentangling takes place between the teeth (wires) of the cylinder or swift and the workers using a point-topoint action (Figure-3). To move the fibers through the process, stripping rollers are used to remove or strip the fibers from the workers through a point-to-back action and these are in turn stripped by the cylinder or swift by the same action. Finally, a fancy roller is used to raise the fibers out of the swift using a back-to-back action, so that they can be formed into a wide fibrous web. The actions are brought about due to the direction of the teeth or wires on the various roller types and their relative surface speeds.
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| Figure-2: Carding actions between the rollers. |
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| Figure-3: Worsted card |
Drawing on the Worsted system uses roller drafting as discussed for short-staple and a number of slivers (often called doublings) are fed in to continue the blending process. The main difference between a short-staple drawbox and a Roller Drafted spinning gill box is the steel pinned combs that act exactly like a comb being drawn through your hair (Figure-4). These control the fiber movements and are very effective in orienting the fibers all in the same direction (parallelizing).
 |
| Figure-4: Gill box |
The carded slivers are fed through two or three of the gill boxes and are then fed into a Worsted combing machine. As with short-staple spinning, the combing machine uses a technologically complicated process. As design technologists, we do not need to study this process, but rather it is important that we understand that it is used to remove short fibers (known as noil) from the slivers to allow the processing of the highest quality worsted/ roller-drafted yarns with as little evidence of hairiness as possible.
Top Making:
This stage consists, once again, of a gill box at the delivery end of which the sliver is wound/coiled into a self-contained and easy-to-transport ball top of around 3–5 kg or packed into a large 25–30 kg bump top. Both forms are then transported to the fiber preparation for spinning stages. Nowadays, the conversion of raw material to a combed top form is mostly carried out in a separate mill to the fiber preparation and spinning mill. Sometimes the tops will be dyed before delivery to or at the spinning mill.
Drawing:
This process also uses gill boxes (though at this stage they are usually called drawboxes). There are normally three drawing/gilling stages used at this stage with progressively finer toothed combs and increasing drafts. The main difference is that an auto-leveling system is used on the second and third box to continuously alter the draft through the speed of the back rollers. If the slivers get heavier, the back rollers are slowed down giving more draft and if the slivers are lighter, the back rollers are speed up giving more draft. By this means, the linear density of the emerging sliver is kept as even as possible.
Roving:
This is very similar to the speed frame/roving process described for short-staple spinning. Again, a sliver is fed in to the back rollers of a roller drafting system and aprons are used to control the movement of fibers in the drafting zone. The linear density (count) of the sliver fed to the roving machine will be in the region of 10 kilotex and a draft of around 10 will be used to reduce the count of the sliver to 1 kilotex. At this linear density, a small amount of twist is required to provide cohesion to the roving, which is what the sliver is now called and this twist is also of importance to help in the drafting of the roving down to the required linear density at the spinning process.
Spinning:
Worsted spinning frames are very similar to short-staple frames, using roller drafting, aprons to control the fibers during drafting and a ring and traveler system to insert the required amount of twist and to wind the yarn onto a tube. Winding onto cones and folding or twisting into two ply yarns is carried out as for all conventional yarns.
Worsted yarns are spun on any kind of spinning machine – mule, ring, cap, or flyer. The two principle systems of spinning worsted yarns are the English system and the French system. In the English system (Bradford), the fiber is oiled before combing, and a tight twist is inserted. This produces smoother and finer yarns. The more tightly twisted yarn makes stronger, more durable fabrics. In the French system, no oil is used. The yarn is given no twist; it is fuzzier, and therefore suitable for soft worsted yarns.
References:
- Textile and Clothing Design Technology Edited by Tom Cassidy and Parikshit Goswami Textile Dyes by N. N. Mahapatra
- https://en.wikipedia.org
- https://www.slideshare.net/
