Woolen Yarn Manufacturing

Introduction

Wool fiber and hair fiber are the natural hair growth of certain animals and are composed of protein. Protein consists of complex organic compounds containing amino acids.
The Great Britain comes first into the story of wool as producer of raw material. The other chief producing countries are Australia, The USSR, New Zealand, Argentina, South Africa, Uruguay and The United States.
The Wool Fiber is obtained from sheep. The breeding of sheep and the production of wool fiber are more costly processes than the cultivation of plant fibers. Consequently, wool fabrics are more expensive than cotton and linen.
Hair fibers have all the qualities of wool and, in general, are more expensive than wool. The hair fibers obtained from the certain animals are;

1. Camel Hair
2. Mohair ( Obtained from Angora Goat)
3. Cashmere (Obtained from cashmere Goat)
4. Llama (Obtained from Camel like animal)
5. Alpaca (Obtained from domesticated animal that resembles Llama)

What are Woolen Yarns

Woolen yarns are thick and made from short staple wool. The fibers in the woolen yarn are held loosely and subjected to only to only a limited or less twist during spinning. These yarns are woven into thick bulkier materials such as jackets, sweaters, skirts, blankets etc. The maximum length of woolen yarn that can be spun from one pound is 54 hanks each of 256 yards.

Manufacturing Process

Flowchart of Woolen Yarn Manufacturing

Sheep

Wool comes from sheep. They grow a wool coat and once a year this wool coat is sheared off the animal. This is frequently done in the early spring shortly before they have their lambs. A shorn ewe will be more likely to stay out of the wind and bad weather and protect her new-born lamb if she does not have a thick wool coat on her.

Fleece

The shorn wool coat is called a fleece. It is also called "grease wool" because of all the oil and lanolin in the wool. This fleece must be cleaned before it can be processed into wool yarn. There is much vegetable matter, manure and natural oil that must be removed. Sometimes as much as 50% of the weight of the fleece is not wool.

Skirting a fleece

The wool from the back end of the sheep, their legs and sometimes their belly is too full of manure to use. These are referred to as "tags". These are removed first before washing the fleece; this process is called skirting, as all the edges of the wool coat are removed. The fleeces are also sorted into the various types: fine from coarse, short from long and black and white.

Cleaning and Scouring

Wool taken directly from the sheep is called "raw" or "grease wool". It contains sand, dirt, grease and dried sweat (called suint). The weight of contaminants accounts for about 30 to 70 percent of the fleece's total weight. To remove these contaminants, the wool is scoured in a series of alkaline baths containing water, soap and soda ash or a similar alkali. Rollers in the scouring machines squeeze excess water from the fleece, but fleece is not allowed to dry completely.

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. The process begins by immersing the wool in a solution of sulfuric acid (H2SO4) that reacts with the cellulose impurities in the wool.

Drying

After scouring and carbonizing of wool, it is necessary to dry it before passing it to the next manufacturing process.

Blending

Blending refers to the process of combining small amounts of the same fiber taken from different lots to achieve a uniform result. Blending of wool is done to combine fibers of different origins, length, thickness or color to make yarn.

Carding

The wool fibers are then put through a series of combing steps called carding. It is done with machine driven drums covered with "card cloth" which combs the wool many times by transferring it back and forth from one drum to the other as it is passed down the series of drums. We have "woolen" cards which produce a wool web with the fibers coming off in random alignment. This is in contrast to "worsted" combing that lines up all the fibers.

Roving

The final step in the carding process divides the web into small strips called pencil roving. These are collected on large spools on the end of the card. These spools of pencil roving will be placed on the spinning frame to make yarn.

Spinning

The roving as it comes off the card has no twist. It is held together by the oil and natural hooks that exist on the surface of the wool fibers. The spinning frame will put the actual twist on the roving and turn it into yarn. This is collected on wooden bobbins.

Wind and/or Skeining

When the wooden bobbins are full of yarn, they are placed on a cone winder and the yarn is transferred to paper cones for use in weaving and knitting machines. It could also be put into skeins of yarn which are the form that knitters like to use.

Finishing

There are many ways of finishing the yarn. It is sometimes necessary to remove the lubricant by washing, which also "sets the twist" which allows the fibers to open up, fluff out and make a loftier yarn. Sometimes the wool is woven or knitted directly from the cone and is washed and blocked in its final form (as cloth, socks, sweaters, etc.).