SHADING

TYPES OF SHADING:
There are three types of shading depending on the size of the cloth.
1. Tappet shedding.
2. Dobby shedding.
3. Jacquard shedding.

TAPPET SHEDDING:

 Tappet shedding is the simplest from the shedding.
 This type of method is used from the plain weave, simple twills and simple sateen and stain weave.
 It is used up to 10 frames.
 AA part from restricted patterning possibilities the chief disadvantage of tappet shedding is that we have to change the tappet at the completion of design.

MECHANISM OFF TAPPET SHEDDING:

The motions are drive from the two steel shaft one position above the other the top shaft is know as crank shaft while bottom is know as tapped shaft.
The motion drive is given from the motor to crank shaft and bottom shaft drives from crank.
When the bottom shaft revolves the tapped revolves on it these tappets are adjusted at different angles. At on time one tappet is pressing to the tappet treadle lever and other is lifting at second tapped liver.
Suppose the liver “B” is down hence the held frame will be up due to reversing system. This will from shed.
The shuttle and other mechanism carrying the weft threads will pass through the shed.

SHEDDING TIMING:
The shedding mechanism starts at above 60º at the crank shaft ay is completed about 120º.














SHEDDING MOTION PARTS:
1. Tappet.
2. Treadle liver.
3. Treadle liver blow.
4. Treadle liver bracket (fulcrum).
5. Adjustable card screw clip.
6. Bottom shaft gear.
7. Crank shaft gear.
8. Crank shaft arm.
9. Top reversing rollers.
10. Healed frame.
11. Top line warp sheet.
12. Bottom line warp sheet.


PICKING:
The processes of throughing shuttle shuttle from one side of the shaft to other side know as picking and this passage is known as pick.

PICKING MECHANISM:
This is second basic mechanism picking after come shading the purpose of this motions is to prepare the shuttle to carry pick into the shed from one side shuttle box to another side shuttle box.
Shuttle is the piece of wood about 14” long and weight about 14” once and automatic looms and 10-------12 once in non automatic loom. Shuttle is changed by workers manually the speed of a loom is no of picks per min.


TYPES OF PICKING MOTIONS:
There are two types of picking mechanism in conventional loom.

1. Over picking motion.
2. Under picking motion.

If the picking system is arranged above the loom, it is called over picking i.e. picking stick is the above the loom.

If the picking system is arranged below the loom, it is called under picking i.e. picking stick is below the loom.








UNDER PICKING MOTION:-
Under picking motion is shown in figure.
The picking stick is located below the shuttle box. There are two plates on bottom shaft having picking bowl. The side lever is fitted below the picking plate. The picking nose is fixed in the side lever.
The side lever up-side of the connecting rod of picking stick. And the picker attached to picking stick strikes the shuttle in the shuttle box. In this way shuttle passes through the shed. There is another same mechanism at the other end causes the shuttle to come back & in this way shuttle goes from one side to another.

PICKING MOTION PARTS:-
A- Picking Stick B- Stick Cam
C- Side Lever D- Crank Shaft
E- Buffer Strap F- Picker
G- Side Lever Bracket H- Adjustable Screw
K- Reed Cap L- Picking bowl
M- Picking Plate N- Picking Nose
O- Picking Shaft U- Slay Sword
P- Reed Q- Crank arm
R- Reed Fly Back S- Side From
T- Bumper

MAIN FEATURES OF UNDER PICKING:-
If is less forceful so it is used for slid loom & fine quality.
It is comparatively cheaper.
Less wears & tears of parts.
It is safe and secure.
It is mostly used for any type of loom and and is very simple mechanism.





Jet weft Insertion or Picking system:-

INTRODUCTION:-
This is one of the shuttles less weft insertion system. This is a very high speed weft insertion rate system. Commonly the weft insertion rate of this system from 2000 m/min to 30, 00 m/min. In this system the weft is inserted though the shed (opening b/w warp threads) from one side of the loom to the other either by using the pressurized air pressure or pressurized water pressure. On the basis of these two wefts insertion sources the looms have been designated as:
Air Jet Loom
Water Jet Loom



AIR JET WEFT INSERTION SYSTEM:-
This is one of the jet weft insertion system whose weft insertion rate is up to 3000 m/min.in this system, pressurized air pressure is used to insert the weft through the shed from one side of the loom to the other.

MECHANISM OF AIR JET WEFT INSERTION SYSTEM:-
There is a weft package creel or stand
(1)_on which the weft package
(2)_either cone or cheer is inserted. From the weft package the weft yarn accumulator which is positively driven by the motor.
(4)_From the yarn accumulator the yarn is fed into the tube of his main nozzle
(6)_There is an air chamber
(7)_around this tube of the main nozzle in which pressurized air is supplied from the air supply tank.
(8)_The yarn coming from the tube of the main nozzle is fed into the shed through teensier and scissor from one side of the loom to the other by the air pressure supplied to the main nozzle. There is a suction nozzle on the other end of the reed which sucks the weft yarn and in order to keep the weft yarn straight and under tension.




























With the help of diagram explain how pick is inserted in projectile loom or slugger loom?

PROJECTILE WEAVING:
1- Projectile 5 moves onto the picking position.
2- Projectile feeder 3 opens after projectile 5 has gripped the filling end presented to it.
3- The projectile has drown the yarn through the shed while filling tensioned lever 2 and adjustable filling brake 1 act to minimize the strain placed on the yarn during picking.
4- The projectile is broken by projectile brake 8 in the receiving unit and pushed back, while the filling tension lever and the filling brake hold the filling yarn lightly stretched. At the same time, the projectile feeder move close to the selvage.
5- Projectile feeder 3 takes over the filling yarn while filling end gripper hold it at both side of the fabric.
6- The yarn is released by the projectile on the receiving side. Filling cutter 4 cuts the filling yarn. A conveyer takes expelled projectile 5 and carries it outside the shed back to the picking position.






















Write detail note on beating up mechanism.

BEATINNG UP:-
Beating up is a process in which weft threads are pushed towards the fell of the cloth with the help of slay on which the reed is mounted. Reed is used to achieve the beating up.

MECHANISM OF BEATING UP:-
In the beating up system a longer crank (or connecting arm) is attached to the crank shaft and other end is connected to slay. The slay is mounted on rocking shaft for easy movement of slay.
When the crank shaft rotates, the connecting arm moves forward and backward. The crank arm is connected to slay which also forward and backward about the rocking shaft. When slay move forward it moves a reed mounted on the top of race board thus reed pushes or beats the inserted pick to the fell of the cloth.

RAPIER LOOM:-
Introduction:-
This is one of the types of shuttle less loom.
It is a versatile loom every type of fabric is commonly made on these loom.
Different counts and fibers can be used to produce the woven fabric.
In this type of weaving a flexible or solid element called rapier is used to insert the filling yarn across the shed.
Commonly two rapier heads are used on one loom. Feeder rapier head and receiver rapier head.
Feeder rapier head which is used to feed the weft yarn from left hand side of the loom to the middle of the reed.
Receiver rapier head which is moved being empty from right hand side of the loom to the middle of the reed to receive the weft yarn from the feeder rapier.
There are commonly three system of rapier drive as given below
1 Single rigid rapier weft insertion or picking system.
2 Double rigid rapier weft insertion or picking system.
3 Double flexible rapier weft insertion.












Single Rigid Rapier Weft Insertion:-
In this system there is only one rapier head which acts as a feeder rapier and it is traversed from one side of the loom to the other side and then the empty rapier is withdrawn leaving the new filling yarn in place.
Speed or weft insertion rate of this loom is low i.e.800 m/min.
Less number of looms can be operated by weaver so the weaver productivity is low.
It occupies more space.
Its noise level is high.
Its mechanism is poor.
The cost /meter of air conditioning are high.

Double Rigid Rapier Weft Insertion:-
In this system two rapier heads are traversed from both side of the loom to insert the weft. it has a certain advantages
1 Because of rapier drive from both sides to the center of the reed, the weft insertion rate of this system is high which is up to 1200m/min.
2 The numbers of loom operated by one weaver are more, so productivity of operator is high.
3 This loom occupies less space.
4 More number of looms can be installed in the size of weaver room.
5 Less cast/meter of air conditioning.
6 Low noise level.

Double Flexible Rapier Weft Insertion:-
This system is superior to other two system of rapier drive in the following respects:
1 Since the drive to the rapier is made by flexible carbon fiber tapes instead of rigid metallic bar hence the speed of this loom is up to 1400m/min.
2 More number of looms can easily be operated by one weaver; hence the productivity of weaver is high.
3 The loom occupies less space.
4 More number of looms can be installed in the same size of weaver room.
5 The noise level of loom is low.
6 Air conditioning cost/meter is high.
7 Quality of the fabric produced is better b/c of the use of carbon fiber types.

MECHENISM OF RAPIER LOOM:-
1 Main drive shaft
2 Cam profile
3 Segment or Quadrant gear
4 Driven pinion
5 Driven sprocket
6 Solid bar
7 Rapier
8 Tension & scissor
9 Reed

There is a cam profile (2) which is transmitted motion from main drive shaft (1) the quadrant or segment gear (3) is oscillated as shown in the figure by arouse by this cam profile. There is a driven pinion (4) which is transmitted motion in clock wise and anti clock wise direction by this quadrant gear. A gear (5) fixed on the same shaft of driven pinion (4) transmit the to and fro motion to solid or rigid bar (6) as shown by arrows in the figure. At the extreme end of the rigid bar a rapier head (7) is fixed. It grips the weft yarn from weft feeder and is passed through the shed from one side of the loom to the other end placing the weft yarn or pick in shed.
As in this system there is only one rapier head which in double rigid rapier same system exist in other side.

WEFT STOPS MOTION:-
This type of stop motion used in shuttle and shuttle less looms. The function of this stop motion is to stop the loom whenever the weft yarn breaks or weft package (porn or cone) exhaust. If this motion is not installed or not functioning properly certain fabric faults like miss pick, crack, float double picks and cut picks etc take place. There is a detector or feeler, may it be mechanical (weft fork) or optical feeler. This plays an important role to operate this motion and stop the loom in time. The function of this detector of feeler is to detect the presence or absence of the weft yarn.
There are various weft stop motion being used on different model of the loom commonly used are.


1 Mechanical weft stop motion
2 Electronic or optical weft stops motion.

There are two weft stop motion in mechanical weft stop motion.
1 Side weft stop fork motion
2 Center weft stop fork motion.
The feelers used are
1 Mechanical feeler i.e. fork
2 Electronic feeler i.e. photo cell

(a) Side Weft Stop Fork Motion:-
In this motion the fork is placed on handle side of the loom. It feels the presence of the weft yarn or absent in the shed. If the weft presence in the shed. The fork will be lifted of its fulcrum so that the fork is cleared of the knock off mechanism and the loom will continuous running. If the weft absent (break or finished) then fork will move with adjacent parts and result loom will be stopped.
(b) Center Weft Fork Stop Motion:-
In center weft fork stop motion is put at the center of the loom. It feels the presence of the weft yarn in the shed on each and every pick. All these circumstances make it desirable to able to stop the loom when the picks break or finished in the shed. The fork must be raised up on each pick if there is no weft yarn supporting the fork the slay come forward to beat up the rod will strike the starting handle and knock off the loom. If the presences of the weft yarn the fork is supported by the weft there is no knock off starting handle and the loom will continuous run.


POSITION OF LET OFF MOTION:
Position off let off motion is controlled by gearing the warp is delivered at regular and even tension throughout the while warp beam these is no defect off then placed on the fabric these motion is good for medium is heavy cloth.
The basic objective off the position left off motion is to prevent the long term tension variation as the beam diameter decreases from full beam to empty beam the advantage of this mechanism is that once the mechanism is set correctly to produce the desired tension further adjustment are not necessary. The weaver does not have to adjust the weight during weaving down of the warp. These are no lost weights rope or chains.

BASIC REQUIREMENTS:
(1) The basic requirements of positive let off are it should mention a uniform warp the mean the warp tension during every loom cycle.

(2) It should meet these two requirements without any further adjustment after the initial setting up the beginning of the warp.

LET OFF MOTION:
Function of the let off mechanism is to allow the warp to move forward by unwinding it from the weavers beam maintaining a predetermined warp tension. The warp tension is essential to form a clear warp shad for essay passage of the shuttle and in helping the fell of the cloth to remain in the same position during the beat up:
The tension on warp should be minimum for the particular quality of fabric as tension above the optimum value tends to increase the warp breakage rate and affect the dimensional and physical properties of the fabric for heavy fabric more tension is required:

TYPE OF LET OFF MECHANISM:
(1) Negative let off motion.
(2) Positive let off motion.

1. NEGATIVE LET OFF MOTION:
In negative let off motion in which warp tension is controlled by weight this is the most common type used on non out mature through these mechanism is very simple and less costly cloth faults like crake and their place can not be avoided. It is also label to cause short medium and long term warp tension variation through the weaving process.
In figure the warp beam is mounted as the back of the loom is tensional by the death weights place on a lever A and is couple to the weights chain or rape by the hook C.