Gas Singeing

Gas Singeing

In this method, gas burners are used to singe one or both sides of the fabric during a single passage of the cloth over the flames.The machine consists of two or more burners supplied with a suitable mixture of gas and air under pressure.The width of the sets of burners can be adjusted to suit the width of the fabric: the length of the flame and hence the intensity of heat can also be adjusted.The cloth in open width is drawn over the flame at high speed at 90 meters per minute, so as to burn the protruding fibers without damaging the cloth.The burn: used is normally a simple iron pipe with suitable perforations along its is length.In the case of slot burner, the width of the slot is adjustable.The mixture of gas and air may be prepared separately and compressed or it may be formed by allowing compressed gas ado and air to mix immediately before the entrance of the slot the chamber.While singeing.the cloth is allowed to run through the pro then

While singeing.the cloth is allowed to run through the machine and then burners are ignited.While stopping the machine, .the flames are first extinguished and then the machine stopped.The high temperature (300 to 500° C) met with in the singeing does not damages the cloth because the time of contact is only fraction of a second.The singeing room is separated from other departments in the mill.The singed cloth is quenched by passing. It  through a mangle revolving in a water box to extinguish sparks and to reduce the risk of fire to the minimum


Synthetic fiber fabrics can also be singed, During singeing such fabrics, the protruding fibers melt and recede from the flame forming minute beads.These absorb the dye faster than.the rest of the fabric giving specky dyeing.In order to avoid this.defect, singeing is carried out after dyeing.In the case of terycot  fabrics, singeing controls pilling 

Roller Singeing

Roller Singeing

In this method, instead of passing the cloth over fixed plates, it is passed over a hollow cylinder of copper or cast iron which is heated internally and is a modification of the plate singeing machine. The cylinder rotates slowly and so presents a fresh hot surface to the oncoming fabric. Further, it rotates in a direction opposite to that of the fabric which raises the nap of the cloth making it particularly suited to the singeing of velvet and, piled fabrics. It is possible to singe both sides, of the cloth in one operation by using two cylinders

In roller singeing, the temperature of the cylinder is more uniform at all places than in the case of plate singeing; hence there is less uneven singeing. This machine, however, also suffers from the disadvantage viz. that it also produces minute grooves when thousand of meters of cloth is passed over the cylinder giving rise to uneven singeing. Also, the fiber ends present in the interstices of warp and weft are not singed since the intense heat does not reach them. Some machines are fitted with a device for sucking away the burnt fibers, The fabric is then quenched by passing it through a mangle revolving in a water.box to extinguish all sparks

Singeing and type of singeing

SINGEING

Another important operation preliminary to the scouring cotton piece goods, though not essential for all types of goods, 15 the removal of projecting fibers from the surface of the cloth by burning known as ' singeing ' .with some fabrics it is sufficient to eliminate dust by brushing and then shear or crop the loose ends of the yarn from the surface ' but singeing is most effective and is almost essential for goods intended for printing and for cloths which are valued for their smooth appearance. Hence the various preparatory processes such as

( I ) Singeing ( for removal of projecting fibers’ )

 ( ii ) Desizing ( for removal of size )

( iii ) Boiling ( for removal of waxy impurities ) and

( iv ) Bleaching ( for removal of natural coloring matter ), may be considered in detail

SINGEING

Singeing is a process carried out for removing ( by burning ) the loose hairy fibers’ projecting from the surface of the cloth thus giving it a smooth appearance, Fabrics intended for printing and other fabrics such as satin, sateen’s, poplin, handkerchiefs, etc . are valued for their smooth appearance and therefore, require to be signed. Goods which are to be mercerized are also singed in order to yield maximum luster in the fabric. The need for singeing of fabric arises on account of the fact that some of the fabrics which protrude from the surface of the yarn during spinning and from the surface of the cloth during weaving give it a fuzzy appearance.  The fabric to be singed should preferably be dried before

singeing as wet cloth may get scorched during singeing. It should not contain acid-liberating substances like zinc chloride which may produce hydroelectric acid on heating and tender the fabric. Singeing should be carried out carefully without scorching or damaging the cloth. It is important to obtain faultless cloth after singeing. Three methods of singeing are commonly used depending on the type of singeing machine used these are

( 1 ) Plate singeing

( 2 ) Roller singeing and

( 3 ) Gas singeing Plate Singeing

Plate Singeing 

In this method, one or two curved copper plates 2.5 to 5 cm thick are used. They are set in the fire clay and heated by a furnace below to bright redness. The cloth in open width is passed over and in contact with the red hot plate at a speed of 150 to 225 meters per minute. The cloth is made to come in contact with a constantly changing part of the plate by an automatic, device. The projecting fibers’ are burnt when the cloth is passed over the plates. One or both sides of the fabric can be singed during a single passage by properly arranging the passage of the fabric. As there is direct contact between the cloth and the hot metallic surface, a certain amount of luster is produced in the cloth due to friction.

The heating of the plates has to be uniform otherwise singeing becomes uneven giving rise to stripes or bars which appear when the cloth is dyed later. It is difficult to maintain the plates at a uniform temperature which is a drawback of this method Another disadvantage is that when thousands of meters of cloth are run through the machine, minute grooves are produced on the surface of the metal which makes uniform contact with the hot surface difficult and thus gives uneven singeing. This defect is noticed after dyeing when the selvages are found to be dyed deeper than the body of the cloth. Further, as the surface of the cloth alone comes in contact. with the hot metallic plate, the fiber ends present in the interstices of warp and weft are, not singed since the intense heat does' not reach them.

After singeing, the cloth is quenched by passing it through a mangle revolving in the water box to extinguish all sparks.