Major Woolen Yarn Manufacturing Stages

The fleece coming from the sheep is put under many processes to make a woolen yarn that are described below:

Scouring

Previous to scouring, the wool as it comes from the sorter is in the majority cases passed through a machine known as duster. The object of dusting grease wools is, as far as possible, to remove before scouring such foreign impurities as lumps of dirt, dust, shives etc.
The operation that follows the dusting of wool is known as wool scouring or washing, and has for its object the cleansing of the wool from the natural and foreign
impurities that, if not removed, would effectually prevent the wool from being worked in the after processes of manufacture. Therefore the primary objectives of wool scouring are to cleanse the wool of the yolk or natural preservative, a greasy matter that covers the outside of the fiber, and at the same time to remove such mechanically adhering impurities as dirt, pieces of manure, etc.
The scouring agents in most common use for cleaning wools are soda ash, carbonate of soda, soda or hard soaps, potash or soft soaps and ammonia. It may be said that for fine grades of wool, a fine quality of soap should be used, a well-made potash soap absolutely free from caustic alkali is preferred. When the wool is very dirty and the grease is stiff and hard, a slightly alkaline liquid will cut the grease from the fiber more quickly, but the greatest care should be taken to prevent injury to the surface of the fiber.

Carbonizing

Carbonizing is done to remove the cellulosic impurities from wool by treatment with acid or acid producing salts. Carbonizing may be carried out in loose wool or on piece goods after scouring. However, it is common practice to carbonize woolen piece goods. The process begins by immersing the wool in a solution of sulfuric acid (H2SO4) that reacts with the cellulose impurities in the wool.
Many major processors of wool use a process called carbonization. Wool is put through a chemical bath of hydrochloric acid and other chemicals to clean the wool. This is different and in addition to a normal scouring of soap. Sulfuric Acid is also used in to carbonize wool specifically to remove dyes from recycled wool.
This type of scouring has many downfalls. The chemicals alone are very harmful and we can only assume that residues are leftover in the finished wool product. This process also strips away all of the natural lanolin which keeps the wool soft and supple. Haven't you ever tried on a wool sweater that was so incredibly itchy scratchy you could not wait to take it off? This is due to carbonization, which rips off the tiny hair follicles on a strand of wool and makes them brittle and ragged causing the wool to be itchy.
The scoured wool fabric is padded, either in the rope form or in open width, with liquor containing dilute sulfuric acid (5 to 7 % by wt.) at approximately 65% wet pick up. And dried at 65 -90 C to concentrate the acid. Baking at 125 C for one minute chars the cellulosic material. The charred vegetable material is brittle and easily crushed on passing the rollers. it can be removed as dust during subsequent mechanical working. After carbonizing the wool fabric should rinsed and neutralized by washing. Such neutralization should be carried out immediately after baking, otherwise fabric damage will occur during storage of wool in such as acidic state. It is convenient to neutralize prior to dyeing but uneven neutralization leads to uneven dyeing.

Drying

After the wool has been carbonized, it is necessary to dry it before passing it to next process of manufacturing, except when the wool is to be dyed in the raw state. The drying of wool is an important process and one on which the condition of the stock largely depends as it is received at the succeeding processes. Wool that is dried quickly with a high temperature, has a harsh, unkind feeling, and the fiber losses its suppleness, becoming stiff and brittle. It is impossible to spin harsh, brittle stock into fine yarn, so that the value of the stock is deteriorated, as the finer yarn a wool will spin, the greater is its value.
Formally wool was dried by spreading it in an open air and allowing the sun and the wind to dry it naturally. This method although slow and laborious, have many advantages over modern methods and the stock when thoroughly dried was soft and kind to the touch, none of its natural qualities being injured. The modern process of drying wool with artificial heat, while accomplished with greater speed is liable if not carefully performed to destroy the life of the wool and render it harsh. Wool that is overheated and baked will also change color and become a dirty yellow shade.

Blending

In yarn production, process of combining fibers of different origins, length, thickness, or color to make yarn. Blending is accomplished before spinning and is performed to impart such desirable characteristics as strength or durability, to reduce cost by combining expensive quality wool fibers with less costly types, or to achieve special color or texture effects. Fabrics made from such fibers are called blends. Blending also done to combine small amounts of the same fiber taken from different lots to achieve a uniform result.

Carding

Similar to the cotton yarn manufacturing the carding process is there to prepare the fleece wool for the process of spinning. This also removes the worst of the dust, dirt, burrs and other plant material from your fleece wool. Following are some other methods which goes in line with the process of carding when it comes to the preparation of the wool fleece to the process of spinning

• Combing
• Flick carding
• Hand carding
• Drum carding

These developments or innovations can be divided in different categories:

• Minor modifications
• Modification related to quality/production monitoring or enhancement in production/speed
• Major modifications

Minor modifications are the simple alteration of the previous version/model of the machine that has nothing to do much with the quality or production/speed of the machine. So these modifications are aimed at just giving the customers a new look to the machine. Second type of modification relates with enhancement in production/speed or with the online quality/production monitoring. Major modifications are really significant modifications, which are helpful in improving the product quality. There are the changes that have been brought in the machine to improve the product quality not only on the same machine but also at subsequent machines. As so far machine manufacturers are concerned, they are providing machines with all the above stated categories, but publicized the machines under the category of major developments though these developments may be coming under first two categories.

Spinning

Spinning is the wool processing step where the wool roving's produced during carding, are turned into yarns. On a commercial wool processing scale the roving's pass through a spinning machine. On an individual scale a spinning wheel or a hand spindle is used. During spinning the wool roving's are gently stretched again. Through a series of twisting and spinning and twisting again the wool is spun into batches of similar quality and strength.
The spun wool is formed into and stored as skeins of yarn, what you see and buy in the store. These are small bundles of yarn that can now be dyed if warranted. During the spinning process other fiber types may be blended with the wool to create various and more unique yarns. Once yarn is produced (or purchased) it can be used for weaving or knitting.