TEXTILE RAW MATERIALS

Raw material is the basic foundation of every product in every industry from where the production start. In textile industry fiber is the basic raw material in any textile industry and these are divided into four classes viz. animals, vegetable, mineral, and artificial fibers.

Animal fiber :  These fiber are hair , wool and silk. Physically, hair and wool belong to same class,but are having different thickness and properties and only wool is used as textile raw material.

Vegetable fiber : These type of fiber are divide into three sub category and these category are following :-

Seed hair(cotton )  , Bast fiber(Flax, Hemp,Jute,Ramie) , Foliaceous fiber.

Mineral fiber : These type of fiber is tough, flexible, and long and is suitable for making 'brattice' cloth and mixing in with wool for building and roofing felts.

Artificial Fiber : These means that are manufactured or made form polyamides , polyester and other synthetic materials .

now, it not compulsory  that these all fiber should be used for making textile product its mainly depend upon the market demand if the market is having a good demand of cotton product then the industry will focus more on the cotton product and if market want more blended product then they will produce more blended product .

now, the next question which arise is that how the raw material is transported to industry so, the answer is that a highly compressed bale of ginned cotton (means the cotton fiber are removed from seed)..In next post  we will discuss about the ginning process and all . 

CARDING THEROY AND THE BASIC ACTION IN CARDING MACHINE

BASIC CARDING ACTIONS

Basically, there are two action in carding machine first , one is carding action (which take place between flats and main cylinder of carding machine) and the second one is the stripping action (which take place between Taker-in and the main cylinder of the carding machine ).    

 Carding action :

In this action the fiber separation process from the fiber tuft is carried out. By held the in between the two wire surface . Now the required condition to carry out carding action are following :-

1. The first condition is that there should be always two wire surface facing each other and they should have the minimum distance of 0.3mm in between them.

2. The second condition is that there is always point  to point facing in between those two wired surface.

3. The third condition is that the interacting surface should move in same direction or in opposite direction. if there are moving in same direction then the charged surface should have to move at higher linear velocity.   

      

 

Stripping action :

In this action the fiber transfer process from one wire surface to other . The necessary condition for stripping actions of fibers are following :-

1. The first condition is that there should be always two wire surface facing each other and they should have minimum distance of 0.3mmin between them.

2. The second condition is that there is always point to back facing in between those two wired surface.

3.  The third condition is that the interacting surface should move in same direction or in opposite direction. if there are moving in same direction then the charged surface should have to move at higher linear velocity.  

Theories of  Carding Machine :-

There are three carding theories which are following  :-

1. Classical theory 

2. Strang's  theory 

3. Kaufman 's theory

1. Carding theory :

 The basic carding and stripping action is know as the carding theory and these action are discussed above in the topic (basic carding action ) . This theory state that the fiber are carded  in between two oppositely inclined wire surface moving at a speed and there is some inclination between the wired points which causes the sliding of the components of fiber tension acting, on the fiber is strong enough to move the fiber down to the wire base. There are some drawback in this theory that is does not take the centrifugal force and the presence of the air current due to rotating elements . The carding force which presses the fibers toward the base of the wire is too small in comparison to components of fiber tufts between  the working surface and centrifugal force acting on the fiber tuft. 

2. Strang's theory : 

In this theory of carding machine is also know as boundary layer theory. This theory state that in the card the cylinder is considered to be enclosed from all the sides by flats , back and front plate ,  licker-in , doffer and cylinder under ceasing and rotate in medium of still air .basically this theory tell that the series of concentric layers of air surround the cylinder and rotates along with it with different velocities. 

The major drawback of this theory is that it is in applicable in explaining the fiber transfer from licker-in to cylinder strang's theory is explaining the carding action in very unrealistic way .

3. Kaufman's theory :

This theory state that as we introduce the fiber tuft into the narrow gap in between the cylinder and flats   the fiber tuft get compression force into the wire clothing of both flats and cylinder . Since the flats are stationary as compared to the fast moving cylinder . According to Kaufman calculation the compression force against the cylinder acts six time lager than the surface area of flats . The penetration of wire points into the tuft is immediately followed by the shearing action on due the greater speed difference the tufts is pulled apart into pieces .

Therefore, these are the carding theory and the basic action carried in carding machine.

 

PRINTING OF COTTON FABRIC WITH HAND BLOCK METHOD

To print cotton fabric with hand block method in direct style, discharge and resist style printing.

Theory : The first textile-printing technique (making impressions) was that using blocks with raised printing surfaces, which were inked and then pressed on to the fabric. By repetition, the image from a single block builds up into a complete design over the fabric area. Some early blocks were made of clay or terracotta, others of carved wood. Wooden blocks carrying design motifs were found in tombs near the ancient town in Upper Egypt. A combination of block printing and painting (usually described as penciling) was used for some time. The biggest problem was that of achieving bright and fast colours. Madder (madder is a fast, rich red colour natural dye stuff obtained from the root of a herb) was the most important dye that was able to satisfy

the need.

Block making: The typical hand block print had no large, uniform areas of colour but was skillfully built up from many small coloured areas, because wooden surfaces largerthan about 10 mm in width would not give an even print. This had the advantage that a motif such as a flower would have an effect of light shade obtained from three or four blocks, each printing a different depth of the same colour or shade. A fairly hard wood was required, such as pear wood, and four or five layers were usually glued together with the grain running in different directions. The design was traced on to the surface and a fine chisel used to cut away the nonprinting areas

to a depth of perhaps 1 cm. To obtain more detail from some blocks, strips and pins of copper or brass (more usually) were hammered into the wood.

Different techniques of hand block printing:

Discharge printing: In this technique before the printing is carried out first the fabric is dyed to desired colour, then the dye is to be removed at selected places by chlorine or other colour destroying chemicals (which yields a white pattern on a coloured ground) from the part of the fabric where the design is to be printed. Coloured patterns on a dyed ground are possible in this method by adding to the bleaching paste a dye not affected by the bleaching agent used, so that another colour is substituted for white on the dyed ground.

Direct block printing: The fabric is first bleached and then dyed with desired colour. After that the hand block printing is done with carved wooden blocks in borders and in the inside of the fabric.

Resist printing: In resist printing the design desired, is printed on the fabric with a material (Wax or resin) which will resist dyeing. The fabric is then dyed with desired colour. Washing after dyeing removes the resist material in which design is printed leaving a white pattern like the following print effect is achieved on the fabric.

 (resist printing)