How Blue Jeans are Made.

How Blue Jeans are Made.

 

Md. Hasanuzzaman Bhuiyan

Dept. of Textile Engineering
Southeast University

Email: hasanuzzaman07@yahoo.com

 https://www.facebook.com/seu.hasan

Introduction:

Blue jeans are casual pants made from denim. They have been worn by sailors and California gold miners as sturdy work pants.  The name for blue jeans was derived from the color of the fabric used to make them. Denim was treated with a blue dye obtained from the indigo plant. Indigo had been used as a dye since 2500 B.C. in such diverse places as Asia, Egypt, Greece, Rome, Britain, and Peru. Blue jean manufacturers imported indigo from India until the twentieth century, when synthetic indigo was developed to replace the natural dye. Blue jeans in the form we know them today didn't come about until the middle of the nineteenth century. Levi Strauss, an enterprising immigrant who happened to have a few bolts of blue denim cloth on hand, recognized a need for strong work pants in the mining communities of California. About 450 million jeans are sold every year in USA market only. World market of jeans is 400 billion dollar.

 Collection of cotton fibers:

Cotton fibers are collected from the land either by human being or machine. In just 5 minutes the machine can harvest much crops as a human being needs whole day. Then cotton fibers are collected and 500 kg of seeds, 100 kg of leaves and 400 kg of cotton fibers found in every 1000 kg of collected cotton. All of these are separated in cotton king machine and cotton bale are produced. Every year there is an amazing ginning of cotton field to the high speed stack. Weight of a cotton bale is about 200 kg and containing enough fiber to produce 325 pieces of jeans. Finally the cotton bales are transferred into the denimar factory for the production of blue jeans.

Blending & Cleaning

Every bale of cotton is likely different. To make consistent thread cotton needs to be blended. A machine is used for this blending operation and Truzschler blendomate machine is one of them. After blending and cleaning the fibers are transferred to the carding section.

Carding 

The first two steps in blue jeans manufacture are carding and spinning. In carding, the cotton is put through a carding machine (DK- 760) with bent wire brushes. The brushes clean, disentangle, straighten, and gather the cotton threads into slier. The speed of 1500 feet per minute 6 slivers combined together.

Spinning

After several slivers are joined together, they are put on rotor spinning machines that twist and stretch the cotton to form yarn. RPM of rotor spinning machine is about 1, 20000 where the ring spinning machine has a RPM of 1500. About 20 grams of fiber produce a whole kilometer of fine yarn.

Dyeing of cotton yarn

Some cloths are woven and then dyed, but denim is usually dyed with chemically synthesized indigo before being woven. Large balls of yarn, called ball warps, are dipped in the indigo mixture several times so that the dye covers the yarn in layers. At first the yarn become yellow but finally it becomes blue. The dyed yarn is then slashed; that is, it is coated with sizing to make the threads stronger and stiffer. Once this operation is complete, the yarn threads are ready to woven.

Weaving 

The yarn is then woven on large mechanical looms. Denim is not 100 percent blue, as the blue dyed threads forming the warp are combined with white threads forming the weft. In this way 3000 miter of fabric is produced every weak. Then the fabric is turned into the garments factory.

Garments

In Mexico the largest jeans factory produce 4, 00000 pieces of jeans every month. The factory produce most famous brand of jeans. A 5 pocket jeans uses 15 pieces of cloth. The desired design is selected; patterns from the design are cut from heavy paper or cardboard. Up to 80 different sizes are possible from one pattern. The pieces of denim are then cut with high speed cutting machines from stacks 100 layers thick. Each piece of jeans take 15 minutes to make and requires 1.6 miter of denim, 700 miters of thread, 6 rivets , 1 zipper and 5 button.

Finishing

After producing the blue jeans it is ironed and then brushing also done and finally different types of design or permanent creases are applied to the jeans and then washed out with the presence of stones for smooth appearance of the jeans. Jeans are placed into a large pressing machine that steam irons the entire garment at once in about a minute. A size tag is punched into the material and the jeans are folded, stacked, and placed in boxes according to style, color, and size before being sent to the warehouse for storage. When the jeans are selected to be sent to a store, they are put in large shipping cartons and sent on freight trains or trucks.