CLASSIFICATION OF MAN-MADE FIBERS

CLASSIFICATION OF MAN-MADE FIBERSMan Made fibers can be classified into three classes:1.     Those made from natural polymers, 2.     Those made from synthetic polymers, 3.     Those made from inorganic materials.

Difference between Rib, interlock and plain

Comparison among plain single jersey, plain rib and plain interlock fabric:

points	Plain s/j fabric	Plain rib fabric	Plain interlock fabric
1.appearance	Face and back side are different	Face and back side are identical	Face and back side are same
2.visibility of Wales	Clearly visible on the face side	Face and back side are identical.	Wales of each side are exactly opposite to each other and locked together
3.extensibility	Widthwise extensibility is twice than lengthwise extensibility	Width and lengthwise extensibility is twice than single jersey	Elongation is same as single jersey
4.curling tendency	Curling occurs at the edges	No curling tendency	No curling tendency
5.thickness	Approximately  twice of yarn diameter	Approximately twice than single jersey	twice than single jersey
7.series of loops	One series of knitted loop for per course	Two series of loops	Two series of loops
8. Derivatives	Single lacoste ,Double lacoste.,Single pique,Polo pique/Double pique,Two thread fleece,Three thread fleece,French terry etc.	2×2 rib,Half cardigan or royal rib,Full cardigan or polka rib,Swiss double pique,French double pique	Single pique or cross tucks interlock,Jersey cord.Eight lock.

Comparison between RIB and INTERLOCK circular knitting machine:

RIB	Interlock
1.Rib has vertical cord appearance	1.it has the technical face of plain fabrics on both sides
2.one type of latch needle is used	2.two types of latch needle is used.
3.one feeder is used at yarn feeding	3.at least two feeders are used
4.relaxation is less	4.more relaxation
5.Dial and cylinder needles are opposite but placed in same sequence.	5. Dial and cylinder needles are opposite and alternatively placed
6.it is not so thick and heavy structure	6. it is so thick and heavy structure
More production rate	7. less production rate
8.used to produce tops of socks, cuffs ,sleeves ,bottom edges of sweaters ,knit hats, means hosiery	8.used to produce underwear, shirts, suits, trousers suits, sports wear, dress

Machineries of blowroom....

HOPPER FEEDER:

 

The cotton coming from previous machine is deposited on creeper latticed Reserve bin.  Creeper lattice will deliver the cotton on feed Lattice of main bin. Feed lattice will take cotton forward close to the inclined lattice. Swing door is used to maintain the constant level of cotton on feed lattice Due to the spikes on the inclined lattice and direction   of movement, lumps bf cotton will  be carried upwards by the inclined lattice. Hard pressed layers of cotton are well combed by the spikes of inclined lattice.revolving   spikes of the evener roller or lattice beats and open the cotton.Due to the close space between evener lattice and inclined lattice and rotation of evener roller in a opposite direction, unopened excess lumps of cottons are thrown back into mixing bin.Stripping roller strip the cotton from inclined lattice and projects it over a grid bar system where sand, heavy trash are passed   through the spacing of the grid.

From stripping roller the cotton is deposited, layer by layer in. the reserve box and is taken into next machine by lattice in the form of uniform feeding across the full width of the scutcher.

Pneumatic Conveyor Air current setup by the fan with condenser in the blow   room line   suck   the   cotton tufts from one machine   and   transfer   or convey   to another through pneumatic conveyor and is fed  to the next machine by condenser.

Object: The main object of hopper feeder is open and feed fiber properly for next process.

PORCUPINE OPENER  

The cotton fed by the previous opener is carried forward by the feed lattice. The sheet of cotton now pass between pedal and pedal roller. The weight of cotton fed per  unit time is maintained constant by this pedal  feed regulating motion.

Pedal roller feed the sheet of cotton in between pair of feed roller which is weighted to give necessary grip on the cotton.16 circular disc are mounted on the shaft of this opener. 14 to 18 striker blades are rivitted alternatively on each circular disc. Each striker is bent to a slightly different angle.The compressed sheet of cotton delivered from the feed roller is heavily beated by the rapidly revolving striker of the porcupine beater against grid bar.Because of this beating action, the cotton is effectively opened and extracted trash particles are passed through the spacing of the grid bar.

At the end of the grid bar, stripping rail is provided, this is a metal bar which is set about 1/16 inch away from the end of the striker. This small clearance between stripping rail and striker   prevents bunches of cotton being carried around   by   the beater.

Step cleaner:

Condenser is employed to feed cotton to the step cleaner. Photo-cell arrangement in the reserve tower unit monitor the height of reserve fibre and signals stop or start commands to the proceeding machine. Cotton is fed from the reserve tower by pair of feed roller. According to the height of cotton level, photo cell in the reserve tower of subsequent machine, drive the feed Roller intermittently by motorised gear reduction unit.  

The rapid revolution of 6 beating cylinders (multiple beater)and beating of the spikes on cotton against grid bar centrifugal force and gravity combine effectively to open the cotton and remove the heavier impurities. 

Heavier impurities, dust & dirt particles, short fibres, etc, from the cotton are passed through the spacing of the bars and is collected outside the grid bar.

KIRSCHNER BEATER :

 Working principle:

Kirschner   Beater   has 3 arms like 3 Bladed   beater   but    in  place   of blades there are wooden lag(5.5 inch wide)  carrying   a large   no. of steel pins (24 Rows) and inclined in the direction of   rotation   and project about 3/8 inch from surface  of  wooden lag.     So,  instead of beating ,here combing action is achieved.The sheet of cotton delivered from feed roll is combed by the revolving steel pins of the beater against the grid across the width of the machine. Lighter impurities are thoroughly extracted from cotton and passed through the grid bars.

Object:  To comb and extract the lighter impurities from cotton.

SCUTCHER:

In addition to the other functions of blowroom machines, the scutcher has to form a lap for supplying material to the cards. Previously, most of these machines were double scutchers; they had two beater positions and two pairs of perforated drums. Machines delivered in recent years have been almost exclusively single scutchers: they have only one beater position (Kirschner beater) and only one pair of perforated drums or even a single drum.

Following are 3 types of scutcher:

 1.Breaker scutcher

2.Finisher scutcher 

3.single process scutcher.

Working system:

Tow way distributor distribute the cotton from opening   andcleaning line of Blow room line into two scutcher equally. Condenser with fan Suck the material from two way distributor and feed it to the reserve bin of hopper feeder. Hopper feeder  (with Reserve feed & delivery ) mix, comb, open and clean the cotton. At last it provide uniform feeding  of cotton upon the lattice, across the full width of scutcher. Pedal feed motion control the feed and maintain the weight of  cotton   fed   per   unit   time   as   constant for lap  weight  unitormity.3 Bladed Beater Open and clean the cotton.Cage   with fan Suck the material  from  Bladed beater,

extract the lighter impurities and it provide uniform feeding as a 3 sheet form on lattice across the full width of the scutcher. Again one set of pedal feed motion, 2 Bladed Beater &   cage with fan is  placed  and above     mentioned  works are achieved/repeated.At last, calender Roller section Compress the   sheet   ofwhich is delivered from cage.Compressed sheet of cotton now pass under the dead roller. and is wound on lap roller, which is called lap.

Objects of the scutcher :

i) To further break down and clean the cotton tufts by a beater

ii) To convert the mass of cotton fibres into a uniform thick sheet of cotton both longitudinally and   transversely  and wound in the form of a compactly built lap.

CONDENSER:

Fan connected with Condenser suck the material from previous machine through pneumatic pipe and deposit it into the Reserve tower   which  feeds to the next machine in the blow room lineThis   condensor is employed to feed cotton to Hopper  feeder of scutcher, step cleaner, etc, Suction   for conveying the fibre from machine to machine   is created by the fan connected to the condenser.

The fibre condensed on to the rotating surface of the cage is removed by the wiper roller and deposited into the reserve feed tower.

 The  condenser and reserve tower unit provide sufficient production and reserve of fibre to meet all demands by the next machine.

Control or production is exercised by a photo cell arrangement in the tower unit which   monitor the height of reserve fibres   and  signals  stop  or start  commands  to the preceding machine.

Cleaning efficiency

Trash% in cotton is estimated by shirley trash Analyser.  Cleaning Efficiency, depends on the following factors.

1.Trash% in feed,

2.Amount of pre-Opening,

3.Speed of Beater,

4.Maturity of Cotton,

5.Nature of Impurities

6.Settings of machine etc.

Steps to be taken while changing the length & hank of the lap

Lap Hank= lap length in hanks/weight in lbs.

To change lap hank, the feeding to the sctucher is altered by following methods.

i)feed roller speed is changed by altering the position of the cone drum belt by trial & errer method to bring the required Lap weight  & lap hank.

ii)front sheet & back sheet position of the reserve box of theHopper feeder & swing door position is altered i.e. weight/unit length   fed to scutcher is altered depending on the required lap hank.  For  example, to get more wt/ yard of   lap front sheet should be moved forward, to increase the volume of the reserve box to get heavier lap.

 iii) in automatic scutcher, press button switches are provided for the regulation of the lap weight per yard and lap hank through a servomoter on the P.I.V. drive. The current postion of the PIV drive and the degree of regulation are clearly indicated on a scale.    It is possible to determine  the  optimum.

Setting very quickly in case of lap hank change overs. In case of automated scutcher, only the basic lap weight per yard is set by using the corresponding press button switches. All adjusments are automatically carried out by the lap weigher.

Control system in Blow room

Following control systems are used in the blow room line to control the feeding and feed the cotton at uniform rate to the scutcher.

1. Photo electric cell is placed in the following places :-

i) Reserve feed tower of hopper feeder, step cleaner etc.

ii) Reserve trunk of automatic scutcher.

iii) Laminar trunk of ERM cleaner.

iv) Filling trunk of chute feeding system.

v) Piano feed regulating motion, in the scutcher.

vi) Front sheet position and swing door of hopper feeder.

vii) Pressure switch in feeding trunk of automatic scutcher.

viii)Solenoids, micro switch,limit switch and relays

Modern Blowroom

In processing the material, different types of machines are necessary, namely those suitable for  opening, those for  cleaning and those for  blending. Different intensities of processing are also required, because the tufts continually become smaller as they pass from stage to stage. Accordingly, while a coarsely clothed cleaning assembly is ideal after the bale opener, for example, it is inappropriate at the end of the line. Therefore, there are no universal machines, and a blowroom line is a sequence of different machines arranged in series and connected by transport ducts. In its own position in the line, each machine gives optimum performance at any other position it gives less than its optimum. Also there may be advantages in different modes of transport, feeding, processing, cleaning and so on from one machine to another along the line. Finally, the assembly of a blowroom line depends among other things on:

1.The type of raw material;

2.The characteristics of the raw material;

3.Waste content;

4.Dirt content;

5.Material throughput;

the number of different origins of the material in a given blend.

In most cases a modern blowroom line consists of the following machines, as shown in (Rieter) and (Trützschler), illustrating two typical blowroom lines.

 8. Rieter blowroom line; 1. Bale opener UNIfloc A 11; 2. Pre-cleaner UNIclean B 12; 3. Homogenous mixer UNImix B 75; 4. Storage and feeding machine UNIstore A 78; 5. Condenser A 21; 6. Card C 60; 7. Sliver Coiler CBA 4

9. Trützschler blowroom line; (conventional, for combed cotton. One line with a number of variations.)

Advantages of modern Blow room line

Modern Blow Room line or latest developments in the B/R machinery consists

1.Modern mixing machine (Automixer, Multimixer, Aeromixer, Latest mixing bale opener etc.,)

2.Improved opener & Beater (ERM cleaner, mono cylinder, axiflo cleaner, Airjet cleaner, etc.)

3.Automatic scutcher.

4.Automatic lap doffing device.

Fabric inspection Faults and their causes

Defects	Causes
Holes	Bad needle, take down mechanism too tight, high tension on yarn, bad yarn needle too tight in their slots, dial height too low or too high, badly tied knots, improper stitch setting.
Drop stitches	Takedown mechanism too loose, defective needles, too loose yarn tension not sufficient, wrong needle timing set, needle tricks closed.
Vertical lines	Defective needle, dirt in needle slots, needle too loose or too tight in the tricks, needles not enough lubricated.
Soiled yarn	Contamination of cones due to miss handling, knot tying with dirty hand.
Rust mark	Rusty needle, rust in tricks.
Slub	Broken filaments being pushed back along the thread line excessive tails of knitter knot.
Loop distortion	Bad and bent needles, bent trick walls, uneven yarn tension, needle timing set wrong, yarn carriers set wrong.

Difference between weaving and knitting

Topics	Weaving	knitting
1.Definition	The fabric forming process by interlacement of warp threads.	The fabric forming process by intermeshing of loops.
2.Elasticity	Very less or no elasticity.	The fabric shows high amount of stretch and elasticity due to loop structure.
3.Dimentional stability	Good dimensional stability which causes less shrinkage.	Less dimensional stability
4.Durability	More durable	Less durable than woven Fabrics.
5.Moisture absorption	The fabric absorbs less moisture	The knitted fabrics absorb more moisture because of their loose construction.
6.Slacking and low sening	The fabric provides good stability due to intersecting of yarns at right angle.	It creates problem after wearing for along time.
7.Air permeability	Air is less permeable due to compact construction woven fabric.	Air permeability is more due to voluminous structure of knitted fabric.
8.Crease	woven fabrics are more inclined to crease .So ironing and iron retention  are better knitted fabric.	Knitted fabrics are more resistant to crease. So it requires no ironing.
9.Production cost	Production cost is more due to warp preparation and desizing process	Production cost is less due to modest manufacturing process.
10.Yarn	TPI of yarn is comparatively higher than knitting yarn.	TPI of yarn is comparatively lower than woven fabric.